mojoshader.c

/**
 * MojoShader; generate shader programs from bytecode of compiled
 *  Direct3D shaders.
 *
 * Please see the file LICENSE.txt in the source's root directory.
 *
 *  This file written by Ryan C. Gordon.
 */

// !!! FIXME: this file really needs to be split up.

// !!! FIXME: I keep changing coding styles for symbols and typedefs.

// Shader bytecode format is described at MSDN:
//  http://msdn2.microsoft.com/en-us/library/ms800307.aspx

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>

#include "mojoshader.h"


// This is the highest shader version we currently support.

#define MAX_SHADER_MAJOR 3
#define MAX_SHADER_MINOR 0


// If SUPPORT_PROFILE_* isn't defined, we assume an implicit desire to support.
//  You get all the profiles unless you go out of your way to disable them.

#ifndef SUPPORT_PROFILE_D3D
#define SUPPORT_PROFILE_D3D 1
#endif

#ifndef SUPPORT_PROFILE_PASSTHROUGH
#define SUPPORT_PROFILE_PASSTHROUGH 1
#endif

#ifndef SUPPORT_PROFILE_GLSL
#define SUPPORT_PROFILE_GLSL 1
#endif

#ifndef SUPPORT_PROFILE_ARB1
#define SUPPORT_PROFILE_ARB1 1
#endif


// Get basic wankery out of the way here...

typedef unsigned int uint;  // this is a printf() helper. don't use for code.

#ifdef _MSC_VER
#define snprintf _snprintf
typedef unsigned __int8 uint8;
typedef unsigned __int16 uint16;
typedef unsigned __int32 uint32;
typedef unsigned __int32 int32;
// Warning Level 4 considered harmful.  :)
#pragma warning(disable: 4100)  // "unreferenced formal parameter"
#pragma warning(disable: 4389)  // "signed/unsigned mismatch"
#else
#include <stdint.h>
typedef uint8_t uint8;
typedef uint16_t uint16;
typedef uint32_t uint32;
typedef int32_t int32;
#endif

#ifdef __GNUC__
#define ISPRINTF(x,y) __attribute__((format (printf, x, y)))
#else
#define ISPRINTF(x,y)
#endif

#define STATICARRAYLEN(x) ( (sizeof ((x))) / (sizeof ((x)[0])) )

#ifdef _WINDOWS  // !!! FIXME: bleh
const char *endline_str = "\r\n";
#else
const char *endline_str = "\n";
#endif

// we need to reference this by explicit value occasionally.
#define OPCODE_RET 28

// Special-case return values from the parsing pipeline...
#define FAIL (-1)
#define NOFAIL (-2)
#define END_OF_STREAM (-3)


// Byteswap magic...

#if ((defined __GNUC__) && (defined __POWERPC__))
    static inline uint32 SWAP32(uint32 x)
    {
        __asm__ __volatile__("lwbrx %0,0,%1" : "=r" (x) : "r" (&x));
        return x;
    } // SWAP32
    static inline uint16 SWAP16(uint16 x)
    {
        __asm__ __volatile__("lhbrx %0,0,%1" : "=r" (x) : "r" (&x));
        return x;
    } // SWAP16
#elif defined(__POWERPC__)
    static inline uint32 SWAP32(uint32 x)
    {
        return ( (((x) >> 24) & 0x000000FF) | (((x) >>  8) & 0x0000FF00) |
                 (((x) <<  8) & 0x00FF0000) | (((x) << 24) & 0xFF000000) );
    } // SWAP32
    static inline uint16 SWAP16(uint16 x)
    {
        return ( (((x) >> 8) & 0x00FF) | (((x) << 8) & 0xFF00) );
    } // SWAP16
#else
#   define SWAP16(x) (x)
#   define SWAP32(x) (x)
#endif

typedef enum
{
    REG_TYPE_TEMP = 0,
    REG_TYPE_INPUT = 1,
    REG_TYPE_CONST = 2,
    REG_TYPE_ADDRESS = 3,
    REG_TYPE_TEXTURE = 3,  // ALSO 3!
    REG_TYPE_RASTOUT = 4,
    REG_TYPE_ATTROUT = 5,
    REG_TYPE_TEXCRDOUT = 6,
    REG_TYPE_OUTPUT = 6,  // ALSO 6!
    REG_TYPE_CONSTINT = 7,
    REG_TYPE_COLOROUT = 8,
    REG_TYPE_DEPTHOUT = 9,
    REG_TYPE_SAMPLER = 10,
    REG_TYPE_CONST2 = 11,
    REG_TYPE_CONST3 = 12,
    REG_TYPE_CONST4 = 13,
    REG_TYPE_CONSTBOOL = 14,
    REG_TYPE_LOOP = 15,
    REG_TYPE_TEMPFLOAT16 = 16,
    REG_TYPE_MISCTYPE = 17,
    REG_TYPE_LABEL = 18,
    REG_TYPE_PREDICATE = 19,
    REG_TYPE_MAX = 19
} RegisterType;

typedef enum
{
    TEXTURE_TYPE_2D = 2,
    TEXTURE_TYPE_CUBE = 3,
    TEXTURE_TYPE_VOLUME = 4,
} TextureType;

// predeclare.
typedef struct Context Context;
struct ConstantsList;

// one emit function for each opcode in each profile.
typedef void (*emit_function)(Context *ctx);

// one emit function for starting output in each profile.
typedef void (*emit_start)(Context *ctx, const char *profilestr);

// one emit function for ending output in each profile.
typedef void (*emit_end)(Context *ctx);

// one emit function for phase opcode output in each profile.
typedef void (*emit_phase)(Context *ctx);

// one emit function for finalizing output in each profile.
typedef void (*emit_finalize)(Context *ctx);

// one emit function for global definitions in each profile.
typedef void (*emit_global)(Context *ctx, RegisterType regtype, int regnum);

// one emit function for relative uniform arrays in each profile.
typedef void (*emit_array)(Context *ctx, int base, int size);

// one emit function for relative constants arrays in each profile.
typedef void (*emit_const_array)(Context *ctx,
                                 const struct ConstantsList *constslist,
                                 int base, int size);

// one emit function for uniforms in each profile.
typedef void (*emit_uniform)(Context *ctx, RegisterType regtype, int regnum,
                             int arraybase, int arraysize);

// one emit function for samplers in each profile.
typedef void (*emit_sampler)(Context *ctx, int stage, TextureType ttype);

// one emit function for attributes in each profile.
typedef void (*emit_attribute)(Context *ctx, RegisterType regtype, int regnum,
                               MOJOSHADER_usage usage, int index, int wmask);

// one args function for each possible sequence of opcode arguments.
typedef int (*args_function)(Context *ctx);

// one state function for each opcode where we have state machine updates.
typedef void (*state_function)(Context *ctx);

// one function for varnames in each profile.
typedef const char *(*varname_function)(Context *c, RegisterType t, int num);

// one function for const var array in each profile.
typedef const char *(*const_array_varname_function)(Context *c, int base, int size);

typedef struct
{
    const char *name;
    emit_start start_emitter;
    emit_end end_emitter;
    emit_phase phase_emitter;
    emit_global global_emitter;
    emit_array array_emitter;
    emit_const_array const_array_emitter;
    emit_uniform uniform_emitter;
    emit_sampler sampler_emitter;
    emit_attribute attribute_emitter;
    emit_finalize finalize_emitter;
    varname_function get_varname;
    const_array_varname_function get_const_array_varname;
} Profile;

typedef enum
{
    RASTOUT_TYPE_POSITION = 0,
    RASTOUT_TYPE_FOG = 1,
    RASTOUT_TYPE_POINT_SIZE = 2,
    RASTOUT_TYPE_MAX = 2
} RastOutType;

typedef enum
{
    MISCTYPE_TYPE_POSITION = 0,
    MISCTYPE_TYPE_FACE = 1,
    MISCTYPE_TYPE_MAX = 1
} MiscTypeType;


// A simple linked list of strings, so we can build the final output without
//  realloc()ing for each new line, and easily insert lines into the middle
//  of the output without much trouble.
typedef struct OutputListNode
{
    char *str;
    struct OutputListNode *next;
} OutputListNode;

typedef struct OutputList
{
    OutputListNode head;
    OutputListNode *tail;
} OutputList;

typedef struct ConstantsList
{
    MOJOSHADER_constant constant;
    struct ConstantsList *next;
} ConstantsList;

typedef struct VariableList
{
    MOJOSHADER_uniformType type;
    int index;
    int count;
    ConstantsList *constant;
    int used;
    struct VariableList *next;
} VariableList;

typedef struct RegisterList
{
    RegisterType regtype;
    int regnum;
    MOJOSHADER_usage usage;
    int index;
    int writemask;
    int misc;
    const VariableList *array;
    struct RegisterList *next;
} RegisterList;

// result modifiers.
#define MOD_SATURATE 0x01
#define MOD_PP 0x02
#define MOD_CENTROID 0x04

// source modifiers.
typedef enum
{
    SRCMOD_NONE,
    SRCMOD_NEGATE,
    SRCMOD_BIAS,
    SRCMOD_BIASNEGATE,
    SRCMOD_SIGN,
    SRCMOD_SIGNNEGATE,
    SRCMOD_COMPLEMENT,
    SRCMOD_X2,
    SRCMOD_X2NEGATE,
    SRCMOD_DZ,
    SRCMOD_DW,
    SRCMOD_ABS,
    SRCMOD_ABSNEGATE,
    SRCMOD_NOT,
    SRCMOD_TOTAL
} SourceMod;


typedef struct
{
    const uint32 *token;   // this is the unmolested token in the stream.
    int regnum;
    int relative;
    int writemask;   // xyzw or rgba (all four, not split out).
    int writemask0;  // x or red
    int writemask1;  // y or green
    int writemask2;  // z or blue
    int writemask3;  // w or alpha
    int orig_writemask;   // writemask before mojoshader tweaks it.
    int result_mod;
    int result_shift;
    RegisterType regtype;
} DestArgInfo;

typedef struct
{
    const uint32 *token;   // this is the unmolested token in the stream.
    int regnum;
    int swizzle;  // xyzw (all four, not split out).
    int swizzle_x;
    int swizzle_y;
    int swizzle_z;
    int swizzle_w;
    SourceMod src_mod;
    RegisterType regtype;
    int relative;
    RegisterType relative_regtype;
    int relative_regnum;
    int relative_component;
    const VariableList *relative_array;
} SourceArgInfo;


#define SCRATCH_BUFFER_SIZE 128
#define SCRATCH_BUFFERS 32

// !!! FIXME: the scratch buffers make Context pretty big.
// !!! FIXME:  might be worth having one set of static scratch buffers that
// !!! FIXME:  are mutex protected?

// Context...this is state that changes as we parse through a shader...
struct Context
{
    MOJOSHADER_malloc malloc;
    MOJOSHADER_free free;
    void *malloc_data;
    const uint32 *tokens;
    uint32 tokencount;
    OutputList *output;
    OutputList globals;
    OutputList helpers;
    OutputList subroutines;
    OutputList mainline_intro;
    OutputList mainline;
    OutputList ignore;
    OutputList *output_stack[2];
    uint8 *output_bytes;  // can be used instead of the OutputLists.
    int indent_stack[2];
    int output_stack_len;
    int output_len; // total strlen; prevents walking the lists just to malloc.
    int indent;
    const char *shader_type_str;
    const char *endline;
    int endline_len;
    const char *failstr;
    char scratch[SCRATCH_BUFFERS][SCRATCH_BUFFER_SIZE];
    int scratchidx;  // current scratch buffer.
    int profileid;
    const Profile *profile;
    MOJOSHADER_shaderType shader_type;
    uint8 major_ver;
    uint8 minor_ver;
    DestArgInfo dest_arg;
    SourceArgInfo source_args[5];
    SourceArgInfo predicate_arg;  // for predicated instructions.
    uint32 dwords[4];
    uint32 version_token;
    int instruction_count;
    uint32 instruction_controls;
    uint32 previous_opcode;
    int loops;
    int reps;
    int max_reps;
    int cmps;
    int scratch_registers;
    int max_scratch_registers;
    int branch_labels_stack_index;
    int branch_labels_stack[32];
    int assigned_branch_labels;
    int assigned_vertex_attributes;
    int last_address_reg_component;
    RegisterList used_registers;
    RegisterList defined_registers;
    int constant_count;
    ConstantsList *constants;
    int uniform_count;
    RegisterList uniforms;
    int attribute_count;
    RegisterList attributes;
    int sampler_count;
    RegisterList samplers;
    VariableList *variables;  // variables to register mapping.
    int have_ctab:1;
    int determined_constants_arrays:1;
    int predicated:1;
    int support_nv2:1;
    int support_glsl120:1;
    int glsl_generated_lit_opcode:1;
};


// Convenience functions for allocators...

static MOJOSHADER_parseData out_of_mem_data = {
    "Out of memory", 0, 0, 0, 0, MOJOSHADER_TYPE_UNKNOWN, 0, 0, 0, 0
};

static const char *out_of_mem_str = "Out of memory";
static inline int out_of_memory(Context *ctx)
{
    if (ctx->failstr == NULL)
        ctx->failstr = out_of_mem_str;  // fail() would call malloc().
    return FAIL;
} // out_of_memory

static inline void *Malloc(Context *ctx, const size_t len)
{
    void *retval = ctx->malloc((int) len, ctx->malloc_data);
    if (retval == NULL)
        out_of_memory(ctx);
    return retval;
} // Malloc


static inline void Free(Context *ctx, void *ptr)
{
    if (ptr != NULL)  // check for NULL in case of dumb free() impl.
        ctx->free(ptr, ctx->malloc_data);
} // Free


// jump between output sections in the context...

static inline void push_output(Context *ctx, OutputList *section)
{
    assert(ctx->output_stack_len < STATICARRAYLEN(ctx->output_stack));
    ctx->output_stack[ctx->output_stack_len] = ctx->output;
    ctx->indent_stack[ctx->output_stack_len] = ctx->indent;
    ctx->output_stack_len++;
    ctx->output = section;
    ctx->indent = 0;
} // push_output

static inline void pop_output(Context *ctx)
{
    assert(ctx->output_stack_len > 0);
    ctx->output_stack_len--;
    ctx->output = ctx->output_stack[ctx->output_stack_len];
    ctx->indent = ctx->indent_stack[ctx->output_stack_len];
} // pop_output


// Shader model version magic...

static inline uint32 ver_ui32(const uint8 major, const uint8 minor)
{
    return ( (((uint32) major) << 16) | (((minor) == 0xFF) ? 0 : (minor)) );
} // version_ui32

static inline int shader_version_supported(const uint8 maj, const uint8 min)
{
    return (ver_ui32(maj,min) <= ver_ui32(MAX_SHADER_MAJOR, MAX_SHADER_MINOR));
} // shader_version_supported

static inline int shader_version_atleast(const Context *ctx, const uint8 maj,
                                         const uint8 min)
{
    return (ver_ui32(ctx->major_ver, ctx->minor_ver) >= ver_ui32(maj, min));
} // shader_version_atleast

static inline int shader_version_exactly(const Context *ctx, const uint8 maj,
                                         const uint8 min)
{
    return ((ctx->major_ver == maj) && (ctx->minor_ver == min));
} // shader_version_exactly

static inline int shader_is_pixel(const Context *ctx)
{
    return (ctx->shader_type == MOJOSHADER_TYPE_PIXEL);
} // shader_is_pixel

static inline int shader_is_vertex(const Context *ctx)
{
    return (ctx->shader_type == MOJOSHADER_TYPE_VERTEX);
} // shader_is_vertex


static inline int isfail(const Context *ctx)
{
    return (ctx->failstr != NULL);
} // isfail


static inline char *get_scratch_buffer(Context *ctx)
{
    if ((ctx->scratchidx >= SCRATCH_BUFFERS) && !isfail(ctx))
    {
        // can't call fail() here, since it calls back into here.
        const char *errstr = "BUG: overflowed scratch buffers";
        char *failstr = (char *) Malloc(ctx, strlen(errstr) + 1);
        if (failstr != NULL)
        {
            strcpy(failstr, errstr);
            ctx->failstr = failstr;
        } // if
    } // if

    ctx->scratchidx = (ctx->scratchidx + 1) % SCRATCH_BUFFERS;
    return ctx->scratch[ctx->scratchidx];
} // get_scratch_buffer


static int failf(Context *ctx, const char *fmt, ...) ISPRINTF(2,3);
static int failf(Context *ctx, const char *fmt, ...)
{
    if (ctx->failstr == NULL)  // don't change existing error.
    {
        char *scratch = get_scratch_buffer(ctx);
        va_list ap;
        va_start(ap, fmt);
        const int len = vsnprintf(scratch, SCRATCH_BUFFER_SIZE, fmt, ap);
        va_end(ap);

        char *failstr = (char *) Malloc(ctx, len + 1);
        if (failstr != NULL)
        {
            // see comments about scratch buffer overflow in output_line().
            if (len < SCRATCH_BUFFER_SIZE)
                strcpy(failstr, scratch);  // copy it over.
            else
            {
                va_start(ap, fmt);
                vsnprintf(failstr, len + 1, fmt, ap);  // rebuild it.
                va_end(ap);
            } // else
            ctx->failstr = failstr;
        } // if
    } // if

    return FAIL;
} // failf


static inline int fail(Context *ctx, const char *reason)
{
    return failf(ctx, "%s", reason);
} // fail


static int output_line(Context *ctx, const char *fmt, ...) ISPRINTF(2,3);
static int output_line(Context *ctx, const char *fmt, ...)
{
    OutputListNode *item = NULL;

    if (isfail(ctx))
        return FAIL;  // we failed previously, don't go on...

    char *scratch = get_scratch_buffer(ctx);

    const int indent = ctx->indent;
    if (indent > 0)
        memset(scratch, '\t', indent);

    va_list ap;
    va_start(ap, fmt);
    const int len = vsnprintf(scratch+indent, SCRATCH_BUFFER_SIZE-indent, fmt, ap) + indent;
    va_end(ap);

    item = (OutputListNode *) Malloc(ctx, sizeof (OutputListNode));
    if (item == NULL)
        return FAIL;

    item->str = (char *) Malloc(ctx, len + 1);
    if (item->str == NULL)
    {
        Free(ctx, item);
        return FAIL;
    } // if

    // If we overflowed our scratch buffer, that's okay. We were going to
    //  allocate anyhow...the scratch buffer just lets us avoid a second
    //  run of vsnprintf().
    if (len < SCRATCH_BUFFER_SIZE)
        strcpy(item->str, scratch);  // copy it over.
    else
    {
        if (indent > 0)
            memset(item->str, '\t', indent);
        va_start(ap, fmt);
        vsnprintf(item->str+indent, len + 1, fmt, ap);  // rebuild it.
        va_end(ap);
    } // else

    item->next = NULL;

    ctx->output->tail->next = item;
    ctx->output->tail = item;
    ctx->output_len += len + ctx->endline_len;

    return 0;
} // output_line


// this is just to stop gcc whining.
static inline int output_blank_line(Context *ctx)
{
    return output_line(ctx, "%s", "");
} // output_blank_line


// !!! FIXME: this is sort of nasty.
static void floatstr(Context *ctx, char *buf, size_t bufsize, float f,
                     int leavedecimal)
{
    const size_t len = snprintf(buf, bufsize, "%f", f);
    if ((len+2) >= bufsize)
        fail(ctx, "BUG: internal buffer is too small");
    else
    {
        char *end = buf + len;
        char *ptr = strchr(buf, '.');
        if (ptr == NULL)
        {
            if (leavedecimal)
                strcat(buf, ".0");
            return;  // done.
        } // if

        while (--end != ptr)
        {
            if (*end != '0')
            {
                end++;
                break;
            } // if
        } // while
        if ((leavedecimal) && (end == ptr))
            end += 2;
        *end = '\0';  // chop extra '0' or all decimal places off.
    } // else
} // floatstr


// Deal with register lists...  !!! FIXME: I sort of hate this.

static void free_reglist(MOJOSHADER_free f, void *d, RegisterList *item)
{
    while (item != NULL)
    {
        RegisterList *next = item->next;
        f(item, d);
        item = next;
    } // while
} // free_reglist

static inline uint32 reg_to_ui32(const RegisterType regtype, const int regnum)
{
    return ( ((uint32) regtype) | (((uint32) regnum) << 16) );
} // reg_to_uint32

static RegisterList *reglist_insert(Context *ctx, RegisterList *prev,
                                    const RegisterType regtype,
                                    const int regnum)
{
    const uint32 newval = reg_to_ui32(regtype, regnum);
    RegisterList *item = prev->next;
    while (item != NULL)
    {
        const uint32 val = reg_to_ui32(item->regtype, item->regnum);
        if (newval == val)
            return item;  // already set, so we're done.
        else if (newval < val)  // insert it here.
            break;
        else // if (newval > val)
        {
            // keep going, we're not to the insertion point yet.
            prev = item;
            item = item->next;
        } // else
    } // while

    // we need to insert an entry after (prev).
    item = (RegisterList *) Malloc(ctx, sizeof (RegisterList));
    if (item != NULL)
    {
        item->regtype = regtype;
        item->regnum = regnum;
        item->usage = MOJOSHADER_USAGE_UNKNOWN;
        item->index = 0;
        item->writemask = 0;
        item->misc = 0;
        item->array = NULL;
        item->next = prev->next;
        prev->next = item;
    } // if

    return item;
} // reglist_insert

static RegisterList *reglist_find(RegisterList *prev, const RegisterType rtype,
                                  const int regnum)
{
    const uint32 newval = reg_to_ui32(rtype, regnum);
    RegisterList *item = prev->next;
    while (item != NULL)
    {
        const uint32 val = reg_to_ui32(item->regtype, item->regnum);
        if (newval == val)
            return item;  // here it is.
        else if (newval < val)  // should have been here if it existed.
            return NULL;
        else // if (newval > val)
        {
            // keep going, we're not to the insertion point yet.
            prev = item;
            item = item->next;
        } // else
    } // while

    return NULL;  // wasn't in the list.
} // reglist_find

static inline const RegisterList *reglist_exists(RegisterList *prev,
                                                 const RegisterType regtype,
                                                 const int regnum)
{
    return (reglist_find(prev, regtype, regnum));
} // reglist_exists

static inline void set_used_register(Context *ctx, const RegisterType regtype,
                                     const int regnum)
{
    reglist_insert(ctx, &ctx->used_registers, regtype, regnum);
} // set_used_register

static inline int get_used_register(Context *ctx, const RegisterType regtype,
                                    const int regnum)
{
    return (reglist_exists(&ctx->used_registers, regtype, regnum) != NULL);
} // get_used_register

static inline void set_defined_register(Context *ctx, const RegisterType rtype,
                                        const int regnum)
{
    reglist_insert(ctx, &ctx->defined_registers, rtype, regnum);
} // set_defined_register

static inline int get_defined_register(Context *ctx, const RegisterType rtype,
                                       const int regnum)
{
    return (reglist_exists(&ctx->defined_registers, rtype, regnum) != NULL);
} // get_defined_register

static const RegisterList *declared_attribute(Context *ctx,
                                              const MOJOSHADER_usage usage,
                                              const int index)
{
    const RegisterList *item = ctx->attributes.next;
    while (item != NULL)
    {
        if ((item->usage == usage) && (item->index == index))
            return item;
        item = item->next;
    } // while

    return NULL;
} // declared_attribute

static void add_attribute_register(Context *ctx, const RegisterType rtype,
                                const int regnum, const MOJOSHADER_usage usage,
                                const int index, const int writemask)
{
    RegisterList *item = reglist_insert(ctx, &ctx->attributes, rtype, regnum);
    item->usage = usage;
    item->index = index;
    item->writemask = writemask;
} // add_attribute_register

static inline void add_sampler(Context *ctx, const RegisterType rtype,
                               const int regnum, const TextureType ttype)
{
    // !!! FIXME: make sure it doesn't exist?
    RegisterList *item = reglist_insert(ctx, &ctx->samplers, rtype, regnum);
    item->index = (int) ttype;
} // add_sampler


static inline int writemask_xyzw(const int writemask)
{
    return (writemask == 0xF);  // 0xF == 1111. No explicit mask (full!).
} // writemask_xyzw


static inline int writemask_xyz(const int writemask)
{
    return (writemask == 0x7);  // 0x7 == 0111. (that is: xyz)
} // writemask_xyz


static inline int writemask_xy(const int writemask)
{
    return (writemask == 0x3);  // 0x3 == 0011. (that is: xy)
} // writemask_xy


static inline int writemask_x(const int writemask)
{
    return (writemask == 0x1);  // 0x1 == 0001. (that is: x)
} // writemask_x


static inline int writemask_y(const int writemask)
{
    return (writemask == 0x2);  // 0x1 == 0010. (that is: y)
} // writemask_y


static inline int replicate_swizzle(const int swizzle)
{
    return ( (((swizzle >> 0) & 0x3) == ((swizzle >> 2) & 0x3)) &&
             (((swizzle >> 2) & 0x3) == ((swizzle >> 4) & 0x3)) &&
             (((swizzle >> 4) & 0x3) == ((swizzle >> 6) & 0x3)) );
} // replicate_swizzle


static inline int scalar_register(const RegisterType regtype, const int regnum)
{
    switch (regtype)
    {
        case REG_TYPE_DEPTHOUT:
        case REG_TYPE_CONSTBOOL:
        case REG_TYPE_PREDICATE:
        case REG_TYPE_LOOP:
            return 1;

        case REG_TYPE_MISCTYPE:
            if ( ((const MiscTypeType) regnum) == MISCTYPE_TYPE_FACE )
                return 1;
            return 0;

        default: break;
    } // switch

    return 0;
} // scalar_register


static inline int no_swizzle(const int swizzle)
{
    return (swizzle == 0xE4);  // 0xE4 == 11100100 ... 0 1 2 3. No swizzle.
} // no_swizzle


static inline int vecsize_from_writemask(const int m)
{
    return (m & 1) + ((m >> 1) & 1) + ((m >> 2) & 1) + ((m >> 3) & 1);
} // vecsize_from_writemask

static int allocate_scratch_register(Context *ctx)
{
    const int retval = ctx->scratch_registers++;
    if (retval >= ctx->max_scratch_registers)
        ctx->max_scratch_registers = retval + 1;
    return retval;
} // allocate_scratch_register

static int allocate_branch_label(Context *ctx)
{
    return ctx->assigned_branch_labels++;
} // allocate_branch_label


// D3D stuff that's used in more than just the d3d profile...

static const char swizzle_channels[] = { 'x', 'y', 'z', 'w' };


static const char *usagestrs[] = {
    "_position", "_blendweight", "_blendindices", "_normal", "_psize",
    "_texcoord", "_tangent", "_binormal", "_tessfactor", "_positiont",
    "_color", "_fog", "_depth", "_sample"
};

static const char *get_D3D_register_string(Context *ctx,
                                           RegisterType regtype,
                                           int regnum, char *regnum_str,
                                           size_t regnum_size)
{
    const char *retval = NULL;
    int has_number = 1;

    switch (regtype)
    {
        case REG_TYPE_TEMP:
            retval = "r";
            break;

        case REG_TYPE_INPUT:
            retval = "v";
            break;

        case REG_TYPE_CONST:
            retval = "c";
            break;

        case REG_TYPE_ADDRESS:  // (or REG_TYPE_TEXTURE, same value.)
            retval = shader_is_vertex(ctx) ? "a" : "t";
            break;

        case REG_TYPE_RASTOUT:
            switch ((RastOutType) regnum)
            {
                case RASTOUT_TYPE_POSITION: retval = "oPos"; break;
                case RASTOUT_TYPE_FOG: retval = "oFog"; break;
                case RASTOUT_TYPE_POINT_SIZE: retval = "oPts"; break;
            } // switch
            has_number = 0;
            break;

        case REG_TYPE_ATTROUT:
            retval = "oD";
            break;

        case REG_TYPE_OUTPUT: // (or REG_TYPE_TEXCRDOUT, same value.)
            if (shader_is_vertex(ctx) && shader_version_atleast(ctx, 3, 0))
                retval = "o";
            else
                retval = "oT";
            break;

        case REG_TYPE_CONSTINT:
            retval = "i";
            break;

        case REG_TYPE_COLOROUT:
            retval = "oC";
            break;

        case REG_TYPE_DEPTHOUT:
            retval = "oDepth";
            has_number = 0;
            break;

        case REG_TYPE_SAMPLER:
            retval = "s";
            break;

        case REG_TYPE_CONSTBOOL:
            retval = "b";
            break;

        case REG_TYPE_LOOP:
            retval = "aL";
            has_number = 0;
            break;

        case REG_TYPE_MISCTYPE:
            switch ((const MiscTypeType) regnum)
            {
                case MISCTYPE_TYPE_POSITION: retval = "vPos"; break;
                case MISCTYPE_TYPE_FACE: retval = "vFace"; break;
            } // switch
            has_number = 0;
            break;

        case REG_TYPE_LABEL:
            retval = "l";
            break;

        case REG_TYPE_PREDICATE:
            retval = "p";
            break;

        //case REG_TYPE_TEMPFLOAT16:  // !!! FIXME: don't know this asm string
        default:
            fail(ctx, "unknown register type");
            retval = "???";
            has_number = 0;
            break;
    } // switch

    if (has_number)
        snprintf(regnum_str, regnum_size, "%u", (uint) regnum);
    else
        regnum_str[0] = '\0';

    return retval;
} // get_D3D_register_string


#define AT_LEAST_ONE_PROFILE 0

#if !SUPPORT_PROFILE_D3D
#define PROFILE_EMITTER_D3D(op)
#else
#undef AT_LEAST_ONE_PROFILE
#define AT_LEAST_ONE_PROFILE 1
#define PROFILE_EMITTER_D3D(op) emit_D3D_##op,

static const char *make_D3D_srcarg_string_in_buf(Context *ctx,
                                                    const SourceArgInfo *arg,
                                                    char *buf, size_t buflen)
{
    const char *premod_str = "";
    const char *postmod_str = "";
    switch (arg->src_mod)
    {
        case SRCMOD_NEGATE:
            premod_str = "-";
            break;

        case SRCMOD_BIASNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_BIAS:
            postmod_str = "_bias";
            break;

        case SRCMOD_SIGNNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_SIGN:
            postmod_str = "_bx2";
            break;

        case SRCMOD_COMPLEMENT:
            premod_str = "1-";
            break;

        case SRCMOD_X2NEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_X2:
            postmod_str = "_x2";
            break;

        case SRCMOD_DZ:
            postmod_str = "_dz";
            break;

        case SRCMOD_DW:
            postmod_str = "_dw";
            break;

        case SRCMOD_ABSNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_ABS:
            postmod_str = "_abs";
            break;

        case SRCMOD_NOT:
            premod_str = "!";
            break;

        case SRCMOD_NONE:
        case SRCMOD_TOTAL:
             break;  // stop compiler whining.
    } // switch


    char regnum_str[16];
    const char *regtype_str = get_D3D_register_string(ctx, arg->regtype,
                                                      arg->regnum, regnum_str,
                                                      sizeof (regnum_str));

    if (regtype_str == NULL)
    {
        fail(ctx, "Unknown source register type.");
        return "";
    } // if

    const char *rel_lbracket = "";
    const char *rel_rbracket = "";
    char rel_swizzle[4] = { '\0' };
    char rel_regnum_str[16] = { '\0' };
    const char *rel_regtype_str = "";
    if (arg->relative)
    {
        rel_swizzle[0] = '.';
        rel_swizzle[1] = swizzle_channels[arg->relative_component];
        rel_swizzle[2] = '\0';
        rel_lbracket = "[";
        rel_rbracket = "]";
        rel_regtype_str = get_D3D_register_string(ctx, arg->relative_regtype,
                                                  arg->relative_regnum,
                                                  rel_regnum_str,
                                                  sizeof (rel_regnum_str));

        if (regtype_str == NULL)
        {
            fail(ctx, "Unknown relative source register type.");
            return "";
        } // if
    } // if

    char swizzle_str[6];
    int i = 0;
    const int scalar = scalar_register(arg->regtype, arg->regnum);
    if (!scalar && !no_swizzle(arg->swizzle))
    {
        swizzle_str[i++] = '.';
        swizzle_str[i++] = swizzle_channels[arg->swizzle_x];
        swizzle_str[i++] = swizzle_channels[arg->swizzle_y];
        swizzle_str[i++] = swizzle_channels[arg->swizzle_z];
        swizzle_str[i++] = swizzle_channels[arg->swizzle_w];

        // .xyzz is the same as .xyz, .z is the same as .zzzz, etc.
        while (swizzle_str[i-1] == swizzle_str[i-2])
            i--;
    } // if
    swizzle_str[i] = '\0';
    assert(i < sizeof (swizzle_str));

    snprintf(buf, buflen, "%s%s%s%s%s%s%s%s%s%s",
             premod_str, regtype_str, regnum_str, postmod_str,
             rel_lbracket, rel_regtype_str, rel_regnum_str, rel_swizzle,
             rel_rbracket, swizzle_str);
    // !!! FIXME: make sure the scratch buffer was large enough.
    return buf;
} // make_D3D_srcarg_string_in_buf


static const char *make_D3D_destarg_string(Context *ctx)
{
    const DestArgInfo *arg = &ctx->dest_arg;

    const char *result_shift_str = "";
    switch (arg->result_shift)
    {
        case 0x1: result_shift_str = "_x2"; break;
        case 0x2: result_shift_str = "_x4"; break;
        case 0x3: result_shift_str = "_x8"; break;
        case 0xD: result_shift_str = "_d8"; break;
        case 0xE: result_shift_str = "_d4"; break;
        case 0xF: result_shift_str = "_d2"; break;
    } // switch

    const char *sat_str = (arg->result_mod & MOD_SATURATE) ? "_sat" : "";
    const char *pp_str = (arg->result_mod & MOD_PP) ? "_pp" : "";
    const char *cent_str = (arg->result_mod & MOD_CENTROID) ? "_centroid" : "";

    char regnum_str[16];
    const char *regtype_str = get_D3D_register_string(ctx, arg->regtype,
                                                      arg->regnum, regnum_str,
                                                      sizeof (regnum_str));
    if (regtype_str == NULL)
    {
        fail(ctx, "Unknown destination register type.");
        return "";
    } // if

    char writemask_str[6];
    int i = 0;
    const int scalar = scalar_register(arg->regtype, arg->regnum);
    if (!scalar && !writemask_xyzw(arg->writemask))
    {
        writemask_str[i++] = '.';
        if (arg->writemask0) writemask_str[i++] = 'x';
        if (arg->writemask1) writemask_str[i++] = 'y';
        if (arg->writemask2) writemask_str[i++] = 'z';
        if (arg->writemask3) writemask_str[i++] = 'w';
    } // if
    writemask_str[i] = '\0';
    assert(i < sizeof (writemask_str));

    const char *pred_left = "";
    const char *pred_right = "";
    char pred[32] = { '\0' };
    if (ctx->predicated)
    {
        pred_left = "(";
        pred_right = ") ";
        make_D3D_srcarg_string_in_buf(ctx, &ctx->predicate_arg,
                                         pred, sizeof (pred));
    } // if

    // may turn out something like "_x2_sat_pp_centroid (!p0.x) r0.xyzw" ...
    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s%s%s%s %s%s%s%s%s%s",
             result_shift_str, sat_str, pp_str, cent_str,
             pred_left, pred, pred_right,
             regtype_str, regnum_str, writemask_str);
    // !!! FIXME: make sure the scratch buffer was large enough.
    return retval;
} // make_D3D_destarg_string


static const char *make_D3D_srcarg_string(Context *ctx, const int idx)
{
    if (idx >= STATICARRAYLEN(ctx->source_args))
    {
        fail(ctx, "Too many source args");
        return "";
    } // if

    const SourceArgInfo *arg = &ctx->source_args[idx];
    char *buf = get_scratch_buffer(ctx);
    return make_D3D_srcarg_string_in_buf(ctx, arg, buf, SCRATCH_BUFFER_SIZE);
} // make_D3D_srcarg_string


static const char *get_D3D_varname(Context *ctx, RegisterType rt, int regnum)
{
    char regnum_str[16];
    const char *regtype_str = get_D3D_register_string(ctx, rt, regnum,
                                              regnum_str, sizeof (regnum_str));

    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s%s", regtype_str, regnum_str);
    return retval;
} // get_D3D_varname

static const char *get_D3D_const_array_varname(Context *ctx, int base, int size)
{
    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "c_array_%d_%d", base, size);
    return retval;
} // get_D3D_const_array_varname


static void emit_D3D_start(Context *ctx, const char *profilestr)
{
    const uint major = (uint) ctx->major_ver;
    const uint minor = (uint) ctx->minor_ver;
    char minor_str[16];

    if (minor == 0xFF)
        strcpy(minor_str, "sw");
    else if (minor == 0x1)  // apparently this is "vs_2_x". Weird.
        strcpy(minor_str, "x");
    else
        snprintf(minor_str, sizeof (minor_str), "%u", (uint) minor);

    output_line(ctx, "%s_%u_%s", ctx->shader_type_str, major, minor_str);
} // emit_D3D_start


static void emit_D3D_end(Context *ctx)
{
    output_line(ctx, "end");
} // emit_D3D_end


static void emit_D3D_phase(Context *ctx)
{
    output_line(ctx, "phase");
} // emit_D3D_phase


static void emit_D3D_finalize(Context *ctx)
{
    // no-op.
} // emit_D3D_finalize


static void emit_D3D_global(Context *ctx, RegisterType regtype, int regnum)
{
    // no-op.
} // emit_D3D_global


static void emit_D3D_array(Context *ctx, int base, int size)
{
    // no-op.
} // emit_D3D_array


static void emit_D3D_const_array(Context *ctx, const ConstantsList *clist,
                                 int base, int size)
{
    // no-op.
} // emit_D3D_const_array


static void emit_D3D_uniform(Context *ctx, RegisterType regtype, int regnum,
                             int arraybase, int arraysize)
{
    // no-op.
} // emit_D3D_uniform


static void emit_D3D_sampler(Context *ctx, int stage, TextureType ttype)
{
    // no-op.
} // emit_D3D_sampler


static void emit_D3D_attribute(Context *ctx, RegisterType regtype, int regnum,
                               MOJOSHADER_usage usage, int index, int wmask)
{
    // no-op.
} // emit_D3D_attribute


static void emit_D3D_RESERVED(Context *ctx)
{
    // do nothing; fails in the state machine.
} // emit_D3D_RESERVED


// Generic D3D opcode emitters. A list of macros generate all the entry points
//  that call into these...

static char *lowercase(char *dst, const char *src)
{
    int i = 0;
    do
    {
        const char ch = src[i];
        dst[i] = (((ch >= 'A') && (ch <= 'Z')) ? (ch - ('A' - 'a')) : ch);
    } while (src[i++]);
    return dst;
} // lowercase


static void emit_D3D_opcode_d(Context *ctx, const char *opcode)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx, "%s%s", opcode, dst0);
} // emit_D3D_opcode_d


static void emit_D3D_opcode_s(Context *ctx, const char *opcode)
{
    const char *src0 = make_D3D_srcarg_string(ctx, 0);
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx, "%s %s", opcode, src0);
} // emit_D3D_opcode_s


static void emit_D3D_opcode_ss(Context *ctx, const char *opcode)
{
    const char *src0 = make_D3D_srcarg_string(ctx, 0);
    const char *src1 = make_D3D_srcarg_string(ctx, 1);
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx, "%s %s, %s", opcode, src0, src1);
} // emit_D3D_opcode_ss


static void emit_D3D_opcode_ds(Context *ctx, const char *opcode)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    const char *src0 = make_D3D_srcarg_string(ctx, 0);
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx, "%s%s, %s", opcode, dst0, src0);
} // emit_D3D_opcode_ds


static void emit_D3D_opcode_dss(Context *ctx, const char *opcode)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    const char *src0 = make_D3D_srcarg_string(ctx, 0);
    const char *src1 = make_D3D_srcarg_string(ctx, 1);
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx, "%s%s, %s, %s", opcode, dst0, src0, src1);
} // emit_D3D_opcode_dss


static void emit_D3D_opcode_dsss(Context *ctx, const char *opcode)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    const char *src0 = make_D3D_srcarg_string(ctx, 0);
    const char *src1 = make_D3D_srcarg_string(ctx, 1);
    const char *src2 = make_D3D_srcarg_string(ctx, 2);
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx, "%s%s, %s, %s, %s", opcode, dst0, src0, src1, src2);
} // emit_D3D_opcode_dsss


static void emit_D3D_opcode_dssss(Context *ctx, const char *opcode)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    const char *src0 = make_D3D_srcarg_string(ctx, 0);
    const char *src1 = make_D3D_srcarg_string(ctx, 1);
    const char *src2 = make_D3D_srcarg_string(ctx, 2);
    const char *src3 = make_D3D_srcarg_string(ctx, 3);
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx,"%s%s, %s, %s, %s, %s",opcode,dst0,src0,src1,src2,src3);
} // emit_D3D_opcode_dssss


static void emit_D3D_opcode(Context *ctx, const char *opcode)
{
    opcode = lowercase(get_scratch_buffer(ctx), opcode);
    output_line(ctx, "%s", opcode);
} // emit_D3D_opcode_dssss


#define EMIT_D3D_OPCODE_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode(ctx, #op); \
    }
#define EMIT_D3D_OPCODE_D_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode_d(ctx, #op); \
    }
#define EMIT_D3D_OPCODE_S_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode_s(ctx, #op); \
    }
#define EMIT_D3D_OPCODE_SS_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode_ss(ctx, #op); \
    }
#define EMIT_D3D_OPCODE_DS_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode_ds(ctx, #op); \
    }
#define EMIT_D3D_OPCODE_DSS_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode_dss(ctx, #op); \
    }
#define EMIT_D3D_OPCODE_DSSS_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode_dsss(ctx, #op); \
    }
#define EMIT_D3D_OPCODE_DSSSS_FUNC(op) \
    static void emit_D3D_##op(Context *ctx) { \
        emit_D3D_opcode_dssss(ctx, #op); \
    }

EMIT_D3D_OPCODE_FUNC(NOP)
EMIT_D3D_OPCODE_DS_FUNC(MOV)
EMIT_D3D_OPCODE_DSS_FUNC(ADD)
EMIT_D3D_OPCODE_DSS_FUNC(SUB)
EMIT_D3D_OPCODE_DSSS_FUNC(MAD)
EMIT_D3D_OPCODE_DSS_FUNC(MUL)
EMIT_D3D_OPCODE_DS_FUNC(RCP)
EMIT_D3D_OPCODE_DS_FUNC(RSQ)
EMIT_D3D_OPCODE_DSS_FUNC(DP3)
EMIT_D3D_OPCODE_DSS_FUNC(DP4)
EMIT_D3D_OPCODE_DSS_FUNC(MIN)
EMIT_D3D_OPCODE_DSS_FUNC(MAX)
EMIT_D3D_OPCODE_DSS_FUNC(SLT)
EMIT_D3D_OPCODE_DSS_FUNC(SGE)
EMIT_D3D_OPCODE_DS_FUNC(EXP)
EMIT_D3D_OPCODE_DS_FUNC(LOG)
EMIT_D3D_OPCODE_DS_FUNC(LIT)
EMIT_D3D_OPCODE_DSS_FUNC(DST)
EMIT_D3D_OPCODE_DSSS_FUNC(LRP)
EMIT_D3D_OPCODE_DS_FUNC(FRC)
EMIT_D3D_OPCODE_DSS_FUNC(M4X4)
EMIT_D3D_OPCODE_DSS_FUNC(M4X3)
EMIT_D3D_OPCODE_DSS_FUNC(M3X4)
EMIT_D3D_OPCODE_DSS_FUNC(M3X3)
EMIT_D3D_OPCODE_DSS_FUNC(M3X2)
EMIT_D3D_OPCODE_S_FUNC(CALL)
EMIT_D3D_OPCODE_SS_FUNC(CALLNZ)
EMIT_D3D_OPCODE_SS_FUNC(LOOP)
EMIT_D3D_OPCODE_FUNC(RET)
EMIT_D3D_OPCODE_FUNC(ENDLOOP)
EMIT_D3D_OPCODE_S_FUNC(LABEL)
EMIT_D3D_OPCODE_DSS_FUNC(POW)
EMIT_D3D_OPCODE_DSS_FUNC(CRS)
EMIT_D3D_OPCODE_DSSS_FUNC(SGN)
EMIT_D3D_OPCODE_DS_FUNC(ABS)
EMIT_D3D_OPCODE_DS_FUNC(NRM)
EMIT_D3D_OPCODE_S_FUNC(REP)
EMIT_D3D_OPCODE_FUNC(ENDREP)
EMIT_D3D_OPCODE_S_FUNC(IF)
EMIT_D3D_OPCODE_FUNC(ELSE)
EMIT_D3D_OPCODE_FUNC(ENDIF)
EMIT_D3D_OPCODE_FUNC(BREAK)
EMIT_D3D_OPCODE_DS_FUNC(MOVA)
EMIT_D3D_OPCODE_D_FUNC(TEXKILL)
EMIT_D3D_OPCODE_DS_FUNC(TEXBEM)
EMIT_D3D_OPCODE_DS_FUNC(TEXBEML)
EMIT_D3D_OPCODE_DS_FUNC(TEXREG2AR)
EMIT_D3D_OPCODE_DS_FUNC(TEXREG2GB)
EMIT_D3D_OPCODE_DS_FUNC(TEXM3X2PAD)
EMIT_D3D_OPCODE_DS_FUNC(TEXM3X2TEX)
EMIT_D3D_OPCODE_DS_FUNC(TEXM3X3PAD)
EMIT_D3D_OPCODE_DS_FUNC(TEXM3X3TEX)
EMIT_D3D_OPCODE_DSS_FUNC(TEXM3X3SPEC)
EMIT_D3D_OPCODE_DS_FUNC(TEXM3X3VSPEC)
EMIT_D3D_OPCODE_DS_FUNC(EXPP)
EMIT_D3D_OPCODE_DS_FUNC(LOGP)
EMIT_D3D_OPCODE_DSSS_FUNC(CND)
EMIT_D3D_OPCODE_DS_FUNC(TEXREG2RGB)
EMIT_D3D_OPCODE_DS_FUNC(TEXDP3TEX)
EMIT_D3D_OPCODE_DS_FUNC(TEXM3X2DEPTH)
EMIT_D3D_OPCODE_DS_FUNC(TEXDP3)
EMIT_D3D_OPCODE_DS_FUNC(TEXM3X3)
EMIT_D3D_OPCODE_D_FUNC(TEXDEPTH)
EMIT_D3D_OPCODE_DSSS_FUNC(CMP)
EMIT_D3D_OPCODE_DSS_FUNC(BEM)
EMIT_D3D_OPCODE_DSSS_FUNC(DP2ADD)
EMIT_D3D_OPCODE_DS_FUNC(DSX)
EMIT_D3D_OPCODE_DS_FUNC(DSY)
EMIT_D3D_OPCODE_DSSSS_FUNC(TEXLDD)
EMIT_D3D_OPCODE_DSS_FUNC(TEXLDL)
EMIT_D3D_OPCODE_S_FUNC(BREAKP)

// special cases for comparison opcodes...
static const char *get_D3D_comparison_string(Context *ctx)
{
    static const char *comps[] = {
        "", "_gt", "_eq", "_ge", "_lt", "_ne", "_le"
    };

    if (ctx->instruction_controls >= STATICARRAYLEN(comps))
    {
        fail(ctx, "unknown comparison control");
        return "";
    } // if

    return comps[ctx->instruction_controls];
} // get_D3D_comparison_string

static void emit_D3D_BREAKC(Context *ctx)
{
    char op[16];
    snprintf(op, sizeof (op), "break%s", get_D3D_comparison_string(ctx));
    emit_D3D_opcode_ss(ctx, op);
} // emit_D3D_BREAKC

static void emit_D3D_IFC(Context *ctx)
{
    char op[16];
    snprintf(op, sizeof (op), "if%s", get_D3D_comparison_string(ctx));
    emit_D3D_opcode_ss(ctx, op);
} // emit_D3D_IFC

static void emit_D3D_SETP(Context *ctx)
{
    char op[16];
    snprintf(op, sizeof (op), "setp%s", get_D3D_comparison_string(ctx));
    emit_D3D_opcode_dss(ctx, op);
} // emit_D3D_SETP

static void emit_D3D_DEF(Context *ctx)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    const float *val = (const float *) ctx->dwords; // !!! FIXME: could be int?
    char val0[32];
    char val1[32];
    char val2[32];
    char val3[32];
    floatstr(ctx, val0, sizeof (val0), val[0], 0);
    floatstr(ctx, val1, sizeof (val1), val[1], 0);
    floatstr(ctx, val2, sizeof (val2), val[2], 0);
    floatstr(ctx, val3, sizeof (val3), val[3], 0);
    output_line(ctx, "def%s, %s, %s, %s, %s", dst0, val0, val1, val2, val3);
} // emit_D3D_DEF

static void emit_D3D_DEFI(Context *ctx)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    const int32 *x = (const int32 *) ctx->dwords;
    output_line(ctx, "defi%s, %d, %d, %d, %d", dst0,
                (int) x[0], (int) x[1], (int) x[2], (int) x[3]);
} // emit_D3D_DEFI

static void emit_D3D_DEFB(Context *ctx)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    output_line(ctx, "defb%s, %s", dst0, ctx->dwords[0] ? "true" : "false");
} // emit_D3D_DEFB


static void emit_D3D_DCL(Context *ctx)
{
    const char *dst0 = make_D3D_destarg_string(ctx);
    const DestArgInfo *arg = &ctx->dest_arg;
    const char *usage_str = "";
    char index_str[16] = { '\0' };

    if (arg->regtype == REG_TYPE_SAMPLER)
    {
        switch ((const TextureType) ctx->dwords[0])
        {
            case TEXTURE_TYPE_2D: usage_str = "_2d"; break;
            case TEXTURE_TYPE_CUBE: usage_str = "_cube"; break;
            case TEXTURE_TYPE_VOLUME: usage_str = "_volume"; break;
            default: fail(ctx, "unknown sampler texture type"); return;
        } // switch
    } // if

    else if (arg->regtype == REG_TYPE_MISCTYPE)
    {
        switch ((const MiscTypeType) arg->regnum)
        {
            case MISCTYPE_TYPE_POSITION:
            case MISCTYPE_TYPE_FACE:
                usage_str = "";  // just become "dcl vFace" or whatever.
                break;
            default: fail(ctx, "unknown misc register type"); return;
        } // switch
    } // else if

    else
    {
        const uint32 usage = ctx->dwords[0];
        const uint32 index = ctx->dwords[1];
        usage_str = usagestrs[usage];
        if (index != 0)
            snprintf(index_str, sizeof (index_str), "%u", (uint) index);
    } // else

    output_line(ctx, "dcl%s%s%s", usage_str, index_str, dst0);
} // emit_D3D_DCL


static void emit_D3D_TEXCRD(Context *ctx)
{
    // this opcode looks and acts differently depending on the shader model.
    if (shader_version_atleast(ctx, 1, 4))
        emit_D3D_opcode_ds(ctx, "texcrd");
    else
        emit_D3D_opcode_d(ctx, "texcoord");
} // emit_D3D_TEXCOORD

static void emit_D3D_TEXLD(Context *ctx)
{
    // this opcode looks and acts differently depending on the shader model.
    if (shader_version_atleast(ctx, 2, 0))
        emit_D3D_opcode_dss(ctx, "texld");
    else if (shader_version_atleast(ctx, 1, 4))
        emit_D3D_opcode_ds(ctx, "texld");
    else
        emit_D3D_opcode_d(ctx, "tex");
} // emit_D3D_TEXLD

static void emit_D3D_SINCOS(Context *ctx)
{
    // this opcode needs extra registers for sm2 and lower.
    if (!shader_version_atleast(ctx, 3, 0))
        emit_D3D_opcode_dsss(ctx, "sincos");
    else
        emit_D3D_opcode_ds(ctx, "sincos");
} // emit_D3D_SINCOS


#undef EMIT_D3D_OPCODE_FUNC
#undef EMIT_D3D_OPCODE_D_FUNC
#undef EMIT_D3D_OPCODE_S_FUNC
#undef EMIT_D3D_OPCODE_SS_FUNC
#undef EMIT_D3D_OPCODE_DS_FUNC
#undef EMIT_D3D_OPCODE_DSS_FUNC
#undef EMIT_D3D_OPCODE_DSSS_FUNC
#undef EMIT_D3D_OPCODE_DSSSS_FUNC

#endif  // SUPPORT_PROFILE_D3D


#if !SUPPORT_PROFILE_PASSTHROUGH
#define PROFILE_EMITTER_PASSTHROUGH(op)
#else
#undef AT_LEAST_ONE_PROFILE
#define AT_LEAST_ONE_PROFILE 1
#define PROFILE_EMITTER_PASSTHROUGH(op) emit_PASSTHROUGH_##op,

static void emit_PASSTHROUGH_start(Context *ctx, const char *profilestr)
{
    // just copy the whole token stream and make all other emitters no-ops.
    ctx->output_len = (ctx->tokencount * sizeof (uint32));
    ctx->output_bytes = (uint8 *) Malloc(ctx, ctx->output_len);
    if (ctx->output_bytes != NULL)
        memcpy(ctx->output_bytes, ctx->tokens, ctx->output_len);
} // emit_PASSTHROUGH_start

static void emit_PASSTHROUGH_end(Context *ctx)
{
    // no-op in this profile.
} // emit_PASSTHROUGH_end

static void emit_PASSTHROUGH_phase(Context *ctx) {}
static void emit_PASSTHROUGH_finalize(Context *ctx) {}
static void emit_PASSTHROUGH_global(Context *ctx, RegisterType t, int n) {}
static void emit_PASSTHROUGH_array(Context *ctx, int base, int size) {}
static void emit_PASSTHROUGH_sampler(Context *ctx, int s, TextureType ttype) {}
static void emit_PASSTHROUGH_const_array(Context *ctx, const ConstantsList *c,
                                         int base, int size) {}
static void emit_PASSTHROUGH_uniform(Context *ctx, RegisterType t, int n,
                                     int arraybase, int arraysize) {}
static void emit_PASSTHROUGH_attribute(Context *ctx, RegisterType t, int n,
                                       MOJOSHADER_usage u, int i, int w) {}

static const char *get_PASSTHROUGH_varname(Context *ctx, RegisterType rt, int regnum)
{
    char regnum_str[16];
    const char *regtype_str = get_D3D_register_string(ctx, rt, regnum,
                                              regnum_str, sizeof (regnum_str));

    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s%s", regtype_str, regnum_str);
    return retval;
} // get_PASSTHROUGH_varname

static const char *get_PASSTHROUGH_const_array_varname(Context *ctx, int base, int size)
{
    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "c_array_%d_%d", base, size);
    return retval;
} // get_PASSTHROUGH_const_array_varname

#define EMIT_PASSTHROUGH_OPCODE_FUNC(op) \
    static void emit_PASSTHROUGH_##op(Context *ctx) {}

EMIT_PASSTHROUGH_OPCODE_FUNC(RESERVED)
EMIT_PASSTHROUGH_OPCODE_FUNC(NOP)
EMIT_PASSTHROUGH_OPCODE_FUNC(MOV)
EMIT_PASSTHROUGH_OPCODE_FUNC(ADD)
EMIT_PASSTHROUGH_OPCODE_FUNC(SUB)
EMIT_PASSTHROUGH_OPCODE_FUNC(MAD)
EMIT_PASSTHROUGH_OPCODE_FUNC(MUL)
EMIT_PASSTHROUGH_OPCODE_FUNC(RCP)
EMIT_PASSTHROUGH_OPCODE_FUNC(RSQ)
EMIT_PASSTHROUGH_OPCODE_FUNC(DP3)
EMIT_PASSTHROUGH_OPCODE_FUNC(DP4)
EMIT_PASSTHROUGH_OPCODE_FUNC(MIN)
EMIT_PASSTHROUGH_OPCODE_FUNC(MAX)
EMIT_PASSTHROUGH_OPCODE_FUNC(SLT)
EMIT_PASSTHROUGH_OPCODE_FUNC(SGE)
EMIT_PASSTHROUGH_OPCODE_FUNC(EXP)
EMIT_PASSTHROUGH_OPCODE_FUNC(LOG)
EMIT_PASSTHROUGH_OPCODE_FUNC(LIT)
EMIT_PASSTHROUGH_OPCODE_FUNC(DST)
EMIT_PASSTHROUGH_OPCODE_FUNC(LRP)
EMIT_PASSTHROUGH_OPCODE_FUNC(FRC)
EMIT_PASSTHROUGH_OPCODE_FUNC(M4X4)
EMIT_PASSTHROUGH_OPCODE_FUNC(M4X3)
EMIT_PASSTHROUGH_OPCODE_FUNC(M3X4)
EMIT_PASSTHROUGH_OPCODE_FUNC(M3X3)
EMIT_PASSTHROUGH_OPCODE_FUNC(M3X2)
EMIT_PASSTHROUGH_OPCODE_FUNC(CALL)
EMIT_PASSTHROUGH_OPCODE_FUNC(CALLNZ)
EMIT_PASSTHROUGH_OPCODE_FUNC(LOOP)
EMIT_PASSTHROUGH_OPCODE_FUNC(RET)
EMIT_PASSTHROUGH_OPCODE_FUNC(ENDLOOP)
EMIT_PASSTHROUGH_OPCODE_FUNC(LABEL)
EMIT_PASSTHROUGH_OPCODE_FUNC(POW)
EMIT_PASSTHROUGH_OPCODE_FUNC(CRS)
EMIT_PASSTHROUGH_OPCODE_FUNC(SGN)
EMIT_PASSTHROUGH_OPCODE_FUNC(ABS)
EMIT_PASSTHROUGH_OPCODE_FUNC(NRM)
EMIT_PASSTHROUGH_OPCODE_FUNC(SINCOS)
EMIT_PASSTHROUGH_OPCODE_FUNC(REP)
EMIT_PASSTHROUGH_OPCODE_FUNC(ENDREP)
EMIT_PASSTHROUGH_OPCODE_FUNC(IF)
EMIT_PASSTHROUGH_OPCODE_FUNC(ELSE)
EMIT_PASSTHROUGH_OPCODE_FUNC(ENDIF)
EMIT_PASSTHROUGH_OPCODE_FUNC(BREAK)
EMIT_PASSTHROUGH_OPCODE_FUNC(MOVA)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXKILL)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXBEM)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXBEML)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXREG2AR)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXREG2GB)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X2PAD)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X2TEX)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X3PAD)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X3TEX)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X3SPEC)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X3VSPEC)
EMIT_PASSTHROUGH_OPCODE_FUNC(EXPP)
EMIT_PASSTHROUGH_OPCODE_FUNC(LOGP)
EMIT_PASSTHROUGH_OPCODE_FUNC(CND)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXREG2RGB)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXDP3TEX)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X2DEPTH)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXDP3)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXM3X3)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXDEPTH)
EMIT_PASSTHROUGH_OPCODE_FUNC(CMP)
EMIT_PASSTHROUGH_OPCODE_FUNC(BEM)
EMIT_PASSTHROUGH_OPCODE_FUNC(DP2ADD)
EMIT_PASSTHROUGH_OPCODE_FUNC(DSX)
EMIT_PASSTHROUGH_OPCODE_FUNC(DSY)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXLDD)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXLDL)
EMIT_PASSTHROUGH_OPCODE_FUNC(BREAKP)
EMIT_PASSTHROUGH_OPCODE_FUNC(BREAKC)
EMIT_PASSTHROUGH_OPCODE_FUNC(IFC)
EMIT_PASSTHROUGH_OPCODE_FUNC(SETP)
EMIT_PASSTHROUGH_OPCODE_FUNC(DEF)
EMIT_PASSTHROUGH_OPCODE_FUNC(DEFI)
EMIT_PASSTHROUGH_OPCODE_FUNC(DEFB)
EMIT_PASSTHROUGH_OPCODE_FUNC(DCL)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXCRD)
EMIT_PASSTHROUGH_OPCODE_FUNC(TEXLD)

#undef EMIT_PASSTHROUGH_OPCODE_FUNC

#endif  // SUPPORT_PROFILE_PASSTHROUGH


#if !SUPPORT_PROFILE_GLSL
#define PROFILE_EMITTER_GLSL(op)
#else
#undef AT_LEAST_ONE_PROFILE
#define AT_LEAST_ONE_PROFILE 1
#define PROFILE_EMITTER_GLSL(op) emit_GLSL_##op,

#define EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(op) \
    static void emit_GLSL_##op(Context *ctx) { \
        fail(ctx, #op " unimplemented in glsl profile"); \
    }

const char *get_GLSL_register_string(Context *ctx, RegisterType regtype,
                                     int regnum, char *regnum_str, int len)
{
    const char *retval = get_D3D_register_string(ctx, regtype, regnum,
                                                 regnum_str, len);
    if (retval == NULL)
    {
        fail(ctx, "Unknown D3D register type.");
        return "";
    } // if

    return retval;
} // get_GLSL_register_string

static const char *get_GLSL_varname(Context *ctx, RegisterType rt, int regnum)
{
    char regnum_str[16];
    const char *regtype_str = get_GLSL_register_string(ctx, rt, regnum,
                                              regnum_str, sizeof (regnum_str));

    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s_%s%s", ctx->shader_type_str,
             regtype_str, regnum_str);
    return retval;
} // get_GLSL_varname


static const char *get_GLSL_const_array_varname(Context *ctx, int base, int size)
{
    const char *shader_type_str = ctx->shader_type_str;
    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s_const_array_%d_%d",
             shader_type_str, base, size);
    return retval;
} // get_GLSL_const_array_varname


static const char *get_GLSL_destarg_varname(Context *ctx)
{
    const DestArgInfo *arg = &ctx->dest_arg;
    return get_GLSL_varname(ctx, arg->regtype, arg->regnum);
} // get_GLSL_destarg_varname

static const char *get_GLSL_srcarg_varname(Context *ctx, int idx)
{
    if (idx >= STATICARRAYLEN(ctx->source_args))
    {
        fail(ctx, "Too many source args");
        return "";
    } // if

    const SourceArgInfo *arg = &ctx->source_args[idx];
    return get_GLSL_varname(ctx, arg->regtype, arg->regnum);
} // get_GLSL_srcarg_varname


static const char *make_GLSL_destarg_assign(Context *, const char *, ...) ISPRINTF(2,3);
static const char *make_GLSL_destarg_assign(Context *ctx, const char *fmt, ...)
{
    int need_parens = 0;
    const DestArgInfo *arg = &ctx->dest_arg;

    if (arg->writemask == 0)
        return "";  // no writemask? It's a no-op.

    char clampbuf[32] = { '\0' };
    const char *clampleft = "";
    const char *clampright = "";
    if (arg->result_mod & MOD_SATURATE)
    {
        const int vecsize = vecsize_from_writemask(arg->writemask);
        clampleft = "clamp(";
        if (vecsize == 1)
            clampright = ", 0.0, 1.0)";
        else
        {
            snprintf(clampbuf, sizeof (clampbuf),
                     ", vec%d(0.0), vec%d(1.0))", vecsize, vecsize);
            clampright = clampbuf;
        } // else
    } // if

    // MSDN says MOD_PP is a hint and many implementations ignore it. So do we.

    if (arg->result_mod & MOD_CENTROID)
    {
        fail(ctx, "MOD_CENTROID unsupported");  // !!! FIXME
        return "";
    } // if

    if (ctx->predicated)
    {
        fail(ctx, "predicated destinations unsupported");  // !!! FIXME
        return "";
    } // if

    char *operation = get_scratch_buffer(ctx);
    va_list ap;
    va_start(ap, fmt);
    const int len = vsnprintf(operation, SCRATCH_BUFFER_SIZE, fmt, ap);
    va_end(ap);
    if (len >= SCRATCH_BUFFER_SIZE)
    {
        fail(ctx, "operation string too large");  // I'm lazy.  :P
        return "";
    } // if

    const char *result_shift_str = "";
    switch (arg->result_shift)
    {
        case 0x1: result_shift_str = " * 2.0"; break;
        case 0x2: result_shift_str = " * 4.0"; break;
        case 0x3: result_shift_str = " * 8.0"; break;
        case 0xD: result_shift_str = " / 8.0"; break;
        case 0xE: result_shift_str = " / 4.0"; break;
        case 0xF: result_shift_str = " / 2.0"; break;
    } // switch
    need_parens |= (result_shift_str[0] != '\0');

    char regnum_str[16];
    const char *regtype_str = get_GLSL_register_string(ctx, arg->regtype,
                                                       arg->regnum, regnum_str,
                                                       sizeof (regnum_str));
    char writemask_str[6];
    int i = 0;
    const int scalar = scalar_register(arg->regtype, arg->regnum);
    if (!scalar && !writemask_xyzw(arg->writemask))
    {
        writemask_str[i++] = '.';
        if (arg->writemask0) writemask_str[i++] = 'x';
        if (arg->writemask1) writemask_str[i++] = 'y';
        if (arg->writemask2) writemask_str[i++] = 'z';
        if (arg->writemask3) writemask_str[i++] = 'w';
    } // if
    writemask_str[i] = '\0';
    assert(i < sizeof (writemask_str));

    const char *leftparen = (need_parens) ? "(" : "";
    const char *rightparen = (need_parens) ? ")" : "";

    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s_%s%s%s = %s%s%s%s%s%s;",
             ctx->shader_type_str, regtype_str, regnum_str, writemask_str,
             clampleft, leftparen, operation, rightparen, result_shift_str,
             clampright);
    // !!! FIXME: make sure the scratch buffer was large enough.
    return retval;
} // make_GLSL_destarg_assign


static char *make_GLSL_swizzle_string(char *swiz_str, const size_t strsize,
                                      const int swizzle, const int writemask)
{
    size_t i = 0;
    if ( (!no_swizzle(swizzle)) || (!writemask_xyzw(writemask)) )
    {
        const int writemask0 = (writemask >> 0) & 0x1;
        const int writemask1 = (writemask >> 1) & 0x1;
        const int writemask2 = (writemask >> 2) & 0x1;
        const int writemask3 = (writemask >> 3) & 0x1;

        const int swizzle_x = (swizzle >> 0) & 0x3;
        const int swizzle_y = (swizzle >> 2) & 0x3;
        const int swizzle_z = (swizzle >> 4) & 0x3;
        const int swizzle_w = (swizzle >> 6) & 0x3;

        swiz_str[i++] = '.';
        if (writemask0) swiz_str[i++] = swizzle_channels[swizzle_x];
        if (writemask1) swiz_str[i++] = swizzle_channels[swizzle_y];
        if (writemask2) swiz_str[i++] = swizzle_channels[swizzle_z];
        if (writemask3) swiz_str[i++] = swizzle_channels[swizzle_w];
    } // if
    assert(i < strsize);
    swiz_str[i] = '\0';
    return swiz_str;
} // make_GLSL_swizzle_string


static char *make_GLSL_srcarg_string(Context *ctx, const int idx,
                                     const int writemask)
{
    if (idx >= STATICARRAYLEN(ctx->source_args))
    {
        fail(ctx, "Too many source args");
        return "";
    } // if

// !!! FIXME: not right.
    const SourceArgInfo *arg = &ctx->source_args[idx];

    const char *premod_str = "";
    const char *postmod_str = "";
    switch (arg->src_mod)
    {
        case SRCMOD_NEGATE:
            premod_str = "-";
            break;

        case SRCMOD_BIASNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_BIAS:
            fail(ctx, "SRCMOD_BIAS unsupported"); return ""; // !!! FIXME
            postmod_str = "_bias";
            break;

        case SRCMOD_SIGNNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_SIGN:
            fail(ctx, "SRCMOD_SIGN unsupported"); return ""; // !!! FIXME
            postmod_str = "_bx2";
            break;

        case SRCMOD_COMPLEMENT:
            fail(ctx, "SRCMOD_COMPLEMENT unsupported"); return ""; // !!! FIXME  (need to handle vecsize)
            premod_str = "(1.0 - (";
            postmod_str = "))";
            break;

        case SRCMOD_X2NEGATE:
            fail(ctx, "SRCMOD_X2NEGATE unsupported"); return ""; // !!! FIXME  (need to handle vecsize)
            premod_str = "-(";
            postmod_str = " * 2.0)";
            break;

        case SRCMOD_X2:
            fail(ctx, "SRCMOD_X2 unsupported"); return ""; // !!! FIXME  (need to handle vecsize)
            premod_str = "(";
            postmod_str = " * 2.0)";
            break;

        case SRCMOD_DZ:
            fail(ctx, "SRCMOD_DZ unsupported"); return ""; // !!! FIXME
            postmod_str = "_dz";
            break;

        case SRCMOD_DW:
            fail(ctx, "SRCMOD_DW unsupported"); return ""; // !!! FIXME
            postmod_str = "_dw";
            break;

        case SRCMOD_ABSNEGATE:
            premod_str = "-abs(";
            postmod_str = ")";
            break;

        case SRCMOD_ABS:
            premod_str = "abs(";
            postmod_str = ")";
            break;

        case SRCMOD_NOT:
            premod_str = "!";
            break;

        case SRCMOD_NONE:
        case SRCMOD_TOTAL:
             break;  // stop compiler whining.
    } // switch

    const char *regtype_str = NULL;

    if (!arg->relative)
        regtype_str = get_GLSL_varname(ctx, arg->regtype, arg->regnum);

    const char *rel_lbracket = "";
    char rel_offset[32] = { '\0' };
    const char *rel_rbracket = "";
    char rel_swizzle[4] = { '\0' };
    const char *rel_regtype_str = "";
    if (arg->relative)
    {
        const int arrayidx = arg->relative_array->index;
        const int arraysize = arg->relative_array->count;
        const int offset = arg->regnum - arrayidx;
        assert(offset >= 0);

        regtype_str = get_GLSL_const_array_varname(ctx, arrayidx, arraysize);
        rel_lbracket = "[";
        if (offset != 0)
            snprintf(rel_offset, sizeof (rel_offset), "%d + ", offset);

        rel_regtype_str = get_GLSL_varname(ctx, arg->relative_regtype,
                                           arg->relative_regnum);
        rel_swizzle[0] = '.';
        rel_swizzle[1] = swizzle_channels[arg->relative_component];
        rel_swizzle[2] = '\0';
        rel_rbracket = "]";
    } // if

    char swiz_str[6] = { '\0' };
    if (!scalar_register(arg->regtype, arg->regnum))
    {
        make_GLSL_swizzle_string(swiz_str, sizeof (swiz_str),
                                 arg->swizzle, writemask);
    } // if

    if (regtype_str == NULL)
    {
        fail(ctx, "Unknown source register type.");
        return "";
    } // if

    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s%s%s%s%s%s%s%s%s",
             premod_str, regtype_str, rel_lbracket, rel_offset,
             rel_regtype_str, rel_swizzle, rel_rbracket, swiz_str,
             postmod_str);
    // !!! FIXME: make sure the scratch buffer was large enough.
    return retval;
} // make_GLSL_srcarg_string

static inline char *make_GLSL_srcarg_string_x(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, (1 << 0));
} // make_GLSL_srcarg_string_x

static inline char *make_GLSL_srcarg_string_y(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, (1 << 1));
} // make_GLSL_srcarg_string_y

static inline char *make_GLSL_srcarg_string_z(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, (1 << 2));
} // make_GLSL_srcarg_string_z

static inline char *make_GLSL_srcarg_string_w(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, (1 << 3));
} // make_GLSL_srcarg_string_w

static inline char *make_GLSL_srcarg_string_scalar(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string_x(ctx, idx);
} // make_GLSL_srcarg_string_scalar

static inline char *make_GLSL_srcarg_string_full(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, 0xF);
} // make_GLSL_srcarg_string_scalar

static inline char *make_GLSL_srcarg_string_masked(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, ctx->dest_arg.writemask);
} // make_GLSL_srcarg_string_scalar

static inline char *make_GLSL_srcarg_string_vec3(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, 0x7);
} // make_GLSL_srcarg_string_vec3

static inline char *make_GLSL_srcarg_string_vec2(Context *ctx, const int idx)
{
    return make_GLSL_srcarg_string(ctx, idx, 0x3);
} // make_GLSL_srcarg_string_vec2


// special cases for comparison opcodes...

static const char *get_GLSL_comparison_string_scalar(Context *ctx)
{
    static const char *comps[] = { "", ">", "==", ">=", "<", "!=", "<=" };
    if (ctx->instruction_controls >= STATICARRAYLEN(comps))
    {
        fail(ctx, "unknown comparison control");
        return "";
    } // if

    return comps[ctx->instruction_controls];
} // get_GLSL_comparison_string_scalar

static const char *get_GLSL_comparison_string_vector(Context *ctx)
{
    static const char *comps[] = {
        "", "greaterThan", "equal", "greaterThanEqual", "lessThan",
        "notEqual", "lessThanEqual"
    };

    if (ctx->instruction_controls >= STATICARRAYLEN(comps))
    {
        fail(ctx, "unknown comparison control");
        return "";
    } // if

    return comps[ctx->instruction_controls];
} // get_GLSL_comparison_string_vector


static void emit_GLSL_start(Context *ctx, const char *profilestr)
{
    if (!shader_is_vertex(ctx) && !shader_is_pixel(ctx))
    {
        failf(ctx, "Shader type %u unsupported in this profile.",
              (uint) ctx->shader_type);
        return;
    } // if

    ctx->output = &ctx->globals;

    if (strcmp(profilestr, MOJOSHADER_PROFILE_GLSL) == 0)
        /* no-op. */ ;

    else if (strcmp(profilestr, MOJOSHADER_PROFILE_GLSL120) == 0)
    {
        ctx->support_glsl120 = 1;
        output_line(ctx, "#version 120");
    } // else if

    else
    {
        failf(ctx, "Profile '%s' unsupported or unknown.", profilestr);
        return;
    } // else

    ctx->output = &ctx->mainline_intro;
    output_line(ctx, "void main()");
    output_line(ctx, "{");
    ctx->output = &ctx->mainline;
    ctx->indent++;
} // emit_GLSL_start

static void emit_GLSL_RET(Context *ctx);
static void emit_GLSL_end(Context *ctx)
{
    // force a RET opcode if we're at the end of the stream without one.
    if (ctx->previous_opcode != OPCODE_RET)
        emit_GLSL_RET(ctx);
} // emit_GLSL_end

static void emit_GLSL_phase(Context *ctx)
{
    // no-op in GLSL.
} // emit_GLSL_phase

static void emit_GLSL_finalize(Context *ctx)
{
    const RegisterList *reg;

    // throw some blank lines around to make source more readable.
    push_output(ctx, &ctx->globals);
    output_blank_line(ctx);
    pop_output(ctx);

    push_output(ctx, &ctx->mainline_intro);
    ctx->indent++;

    // Make sure this is always set, moved from our generic attribute.
    reg = declared_attribute(ctx, MOJOSHADER_USAGE_POSITION, 0);
    if (reg != NULL)
    {
#if 0  // !!! FIXME: probably not necessary?
        // !!! FIXME: only emit if shader didn't definitely set gl_Position.
        output_line(ctx, "gl_Position = %s;",
                            get_GLSL_varname(ctx, reg->regtype, reg->regnum));
#endif
    } // if

    ctx->indent--;
    pop_output(ctx);
} // emit_GLSL_finalize

static void emit_GLSL_global(Context *ctx, RegisterType regtype, int regnum)
{
    const char *varname = get_GLSL_varname(ctx, regtype, regnum);

    push_output(ctx, &ctx->globals);
    switch (regtype)
    {
        case REG_TYPE_ADDRESS:
            output_line(ctx, "ivec4 %s;", varname);
            break;
        case REG_TYPE_PREDICATE:
            output_line(ctx, "bvec4 %s;", varname);
            break;
        case REG_TYPE_TEMP:
            output_line(ctx, "vec4 %s;", varname);
            break;
        case REG_TYPE_LOOP:
            break; // no-op. We declare these in for loops at the moment.
        case REG_TYPE_LABEL:
            break; // no-op. If we see it here, it means we optimized it out.
        default:
            fail(ctx, "BUG: we used a register we don't know how to define.");
            break;
    } // switch
    pop_output(ctx);
} // emit_GLSL_global

static void emit_GLSL_array(Context *ctx, int base, int size)
{
    const char *varname = get_GLSL_const_array_varname(ctx, base, size);
    push_output(ctx, &ctx->globals);
    output_line(ctx, "uniform vec4 %s[%d];", varname, size);
    pop_output(ctx);
} // emit_GLSL_array

static void emit_GLSL_const_array(Context *ctx, const ConstantsList *clist,
                                  int base, int size)
{
    const char *varname = get_GLSL_const_array_varname(ctx, base, size);
    const char *cstr = NULL;
    const int origscratch = ctx->scratchidx;
    int i;

#if 0
    // !!! FIXME: fails on Nvidia's and Apple's GL, even with #version 120.
    // !!! FIXME:  (the 1.20 spec says it should work, though, I think...)
    if (ctx->support_glsl120)
    {
        // GLSL 1.20 can do constant arrays.
        push_output(ctx, &ctx->globals);
        output_line(ctx, "const vec4 %s[%d] = vec4[%d](", varname, size, size);
        ctx->indent++;

        for (i = 0; i < size; i++)
        {
            while (clist->constant.type != MOJOSHADER_UNIFORM_FLOAT)
                clist = clist->next;
            assert(clist->constant.index == (base + i));

            char val0[32];
            char val1[32];
            char val2[32];
            char val3[32];
            floatstr(ctx, val0, sizeof (val0), clist->constant.value.f[0], 1);
            floatstr(ctx, val1, sizeof (val1), clist->constant.value.f[1], 1);
            floatstr(ctx, val2, sizeof (val2), clist->constant.value.f[2], 1);
            floatstr(ctx, val3, sizeof (val3), clist->constant.value.f[3], 1);

            output_line(ctx, "vec4(%s, %s, %s, %s)%s", val0, val1, val2, val3,
                        (i < (size-1)) ? "," : "");

            ctx->scratchidx = origscratch;
            clist = clist->next;
        } // for

        ctx->indent--;
        output_line(ctx, ");");
        pop_output(ctx);
    } // if

    else
#endif
    {
        // stock GLSL 1.0 can't do constant arrays, so make a global array
        //  and assign all entries at the start of the mainline...
        push_output(ctx, &ctx->globals);
        output_line(ctx, "vec4 %s[%d];", varname, size);
        pop_output(ctx);

        push_output(ctx, &ctx->mainline_intro);
        ctx->indent++;
        for (i = 0; i < size; i++)
        {
            while (clist->constant.type != MOJOSHADER_UNIFORM_FLOAT)
                clist = clist->next;
            assert(clist->constant.index == (base + i));
            cstr = get_GLSL_varname(ctx, REG_TYPE_CONST, clist->constant.index);
            output_line(ctx, "%s[%d] = %s;", varname, i, cstr);
            clist = clist->next;
            ctx->scratchidx = origscratch;
        } // for
        ctx->indent--;
        pop_output(ctx);
    } // else
} // emit_GLSL_const_array

static void emit_GLSL_uniform(Context *ctx, RegisterType regtype, int regnum,
                              int arraybase, int arraysize)
{
    const char *varname = get_GLSL_varname(ctx, regtype, regnum);
    const char *type = NULL;
    switch (regtype)
    {
        case REG_TYPE_CONST: type = "vec4"; break;
        case REG_TYPE_CONSTINT: type = "ivec4"; break;
        case REG_TYPE_CONSTBOOL: type = "bvec4"; break;
        default: fail(ctx, "BUG: used a uniform we don't know how to define.");
    } // switch

    push_output(ctx, &ctx->globals);

    if (arraysize <= 0)
        output_line(ctx, "uniform %s %s;", type, varname);
    else
    {
        const int offset = (regnum - arraybase);
        const char *array = get_GLSL_const_array_varname(ctx, arraybase, arraysize);
        output_line(ctx, "#define %s %s[%d]", varname, array, offset);
    } // else

    pop_output(ctx);
} // emit_GLSL_uniform

static void emit_GLSL_sampler(Context *ctx, int stage, TextureType ttype)
{
    const char *varname = get_GLSL_varname(ctx, REG_TYPE_SAMPLER, stage);
    const char *type = NULL;
    switch (ttype)
    {
        case TEXTURE_TYPE_2D: type = "sampler2D"; break;
        case TEXTURE_TYPE_CUBE: type = "samplerCube"; break;
        case TEXTURE_TYPE_VOLUME: type = "sampler3D"; break;
        default: fail(ctx, "BUG: used a sampler we don't know how to define.");
    } // switch

    push_output(ctx, &ctx->globals);
    output_line(ctx, "uniform %s %s;", type, varname);
    pop_output(ctx);
} // emit_GLSL_sampler

static void emit_GLSL_attribute(Context *ctx, RegisterType regtype, int regnum,
                                MOJOSHADER_usage usage, int index, int wmask)
{
    // !!! FIXME: this function doesn't deal with write masks at all yet!
    const char *varname = get_GLSL_varname(ctx, regtype, regnum);
    const char *usage_str = NULL;
    const char *arrayleft = "";
    const char *arrayright = "";
    char index_str[16] = { '\0' };

    if (index != 0)  // !!! FIXME: a lot of these MUST be zero.
        snprintf(index_str, sizeof (index_str), "%u", (uint) index);

    if (shader_is_vertex(ctx))
    {
        // pre-vs3 output registers.
        // these don't ever happen in DCL opcodes, I think. Map to vs_3_*
        //  output registers.
        if (!shader_version_atleast(ctx, 3, 0))
        {
            if (regtype == REG_TYPE_RASTOUT)
            {
                regtype = REG_TYPE_OUTPUT;
                index = regnum;
                switch ((const RastOutType) regnum)
                {
                    case RASTOUT_TYPE_POSITION:
                        usage = MOJOSHADER_USAGE_POSITION;
                        break;
                    case RASTOUT_TYPE_FOG:
                        usage = MOJOSHADER_USAGE_FOG;
                        break;
                    case RASTOUT_TYPE_POINT_SIZE:
                        usage = MOJOSHADER_USAGE_POINTSIZE;
                        break;
                } // switch
            } // if

            else if (regtype == REG_TYPE_ATTROUT)
            {
                regtype = REG_TYPE_OUTPUT;
                usage = MOJOSHADER_USAGE_COLOR;
                index = regnum;
            } // else if

            else if (regtype == REG_TYPE_TEXCRDOUT)
            {
                regtype = REG_TYPE_OUTPUT;
                usage = MOJOSHADER_USAGE_TEXCOORD;
                index = regnum;
            } // else if
        } // if

        // to avoid limitations of various GL entry points for input
        // attributes (glSecondaryColorPointer() can only take 3 component
        // items, glVertexPointer() can't do GL_UNSIGNED_BYTE, many other
        // issues), we set up all inputs as generic vertex attributes, so we
        // can pass data in just about any form, and ignore the built-in GLSL
        // attributes like gl_SecondaryColor. Output needs to use the the
        // built-ins, though, but we don't have to worry about the GL entry
        // point limitations there.

        if (regtype == REG_TYPE_INPUT)
        {
            push_output(ctx, &ctx->globals);
            output_line(ctx, "attribute vec4 %s;", varname);
            pop_output(ctx);
        } // if

        else if (regtype == REG_TYPE_OUTPUT)
        {
            switch (usage)
            {
                case MOJOSHADER_USAGE_POSITION:
                    usage_str = "gl_Position";
                    break;
                case MOJOSHADER_USAGE_POINTSIZE:
                    usage_str = "gl_PointSize";
                    break;
                case MOJOSHADER_USAGE_COLOR:
                    index_str[0] = '\0';  // no explicit number.
                    if (index == 0)
                        usage_str = "gl_FrontColor";
                    else if (index == 1)
                        usage_str = "gl_FrontSecondaryColor";
                    break;
                case MOJOSHADER_USAGE_FOG:
                    usage_str = "gl_FogFragCoord";
                    break;
                case MOJOSHADER_USAGE_TEXCOORD:
                    snprintf(index_str, sizeof (index_str), "%u", (uint) index);
                    usage_str = "gl_TexCoord";
                    arrayleft = "[";
                    arrayright = "]";
                    break;
                default:
                    // !!! FIXME: we need to deal with some more built-in varyings here.
                    break;
            } // switch

            // !!! FIXME: the #define is a little hacky, but it means we don't
            // !!! FIXME:  have to track these separately if this works.
            push_output(ctx, &ctx->globals);
            // no mapping to built-in var? Just make it a regular global, pray.
            if (usage_str == NULL)
                output_line(ctx, "vec4 %s;", varname);
            else
            {
                output_line(ctx, "#define %s %s%s%s%s", varname, usage_str,
                            arrayleft, index_str, arrayright);
            } // else
            pop_output(ctx);
        } // else if

        else
        {
            fail(ctx, "unknown vertex shader attribute register");
        } // else
    } // if

    else if (shader_is_pixel(ctx))
    {
        // samplers DCLs get handled in emit_GLSL_sampler().

        if (regtype == REG_TYPE_COLOROUT)
            usage_str = "gl_FragColor";

        else if (regtype == REG_TYPE_DEPTHOUT)
            usage_str = "gl_FragDepth";

        // !!! FIXME: can you actualy have a texture register with COLOR usage?
        else if ((regtype == REG_TYPE_TEXTURE) || (regtype == REG_TYPE_INPUT))
        {
            if (usage == MOJOSHADER_USAGE_TEXCOORD)
            {
                snprintf(index_str, sizeof (index_str), "%u", (uint) index);
                usage_str = "gl_TexCoord";
                arrayleft = "[";
                arrayright = "]";
            } // if

            else if (usage == MOJOSHADER_USAGE_COLOR)
            {
                index_str[0] = '\0';  // no explicit number.
                if (index == 0)
                    usage_str = "gl_Color";
                else if (index == 1)
                    usage_str = "gl_SecondaryColor";
                else
                    fail(ctx, "unsupported color index");
            } // else if
        } // else if

        else if (regtype == REG_TYPE_MISCTYPE)
        {
            const MiscTypeType mt = (MiscTypeType) regnum;
            if (mt == MISCTYPE_TYPE_FACE)
            {
                push_output(ctx, &ctx->globals);
                output_line(ctx, "float %s = gl_FrontFacing ? 1.0 : -1.0;",
                            varname);
                pop_output(ctx);
            } // if
            else if (mt == MISCTYPE_TYPE_POSITION)
            {
                index_str[0] = '\0';  // no explicit number.
                usage_str = "gl_FragCoord";  // !!! FIXME: is this the same coord space as D3D?
            } // else if
            else
            {
                fail(ctx, "BUG: unhandled misc register");
            } // else
        } // else if

        else
        {
            fail(ctx, "unknown pixel shader attribute register");
        } // else

        if (usage_str != NULL)
        {
            push_output(ctx, &ctx->globals);
            output_line(ctx, "#define %s %s%s%s%s", varname, usage_str,
                        arrayleft, index_str, arrayright);
            pop_output(ctx);
        } // if
    } // else if

    else
    {
        fail(ctx, "Unknown shader type");  // state machine should catch this.
    } // else
} // emit_GLSL_attribute

static void emit_GLSL_NOP(Context *ctx)
{
    // no-op is a no-op.  :)
} // emit_GLSL_NOP

static void emit_GLSL_MOV(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "%s", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_MOV

static void emit_GLSL_ADD(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx, "%s + %s", src0, src1);
    output_line(ctx, "%s", code);
} // emit_GLSL_ADD

static void emit_GLSL_SUB(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx, "%s - %s", src0, src1);
    output_line(ctx, "%s", code);
} // emit_GLSL_SUB

static void emit_GLSL_MAD(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *src2 = make_GLSL_srcarg_string_masked(ctx, 2);
    const char *code = make_GLSL_destarg_assign(ctx, "(%s * %s) + %s", src0, src1, src2);
    output_line(ctx, "%s", code);
} // emit_GLSL_MAD

static void emit_GLSL_MUL(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx, "%s * %s", src0, src1);
    output_line(ctx, "%s", code);
} // emit_GLSL_MUL

static void emit_GLSL_RCP(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "1.0 / %s", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_RCP

static void emit_GLSL_RSQ(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "inversesqrt(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_RSQ

static void emit_GLSL_dotprod(Context *ctx, const char *src0, const char *src1,
                              const char *extra)
{
    const int vecsize = vecsize_from_writemask(ctx->dest_arg.writemask);
    char castleft[16] = { '\0' };
    const char *castright = "";
    if (vecsize != 1)
    {
        snprintf(castleft, sizeof (castleft), "vec%d(", vecsize);
        castright = ")";
    } // if

    const char *code = make_GLSL_destarg_assign(ctx, "%sdot(%s, %s)%s%s",
                        castleft, src0, src1, extra, castright);
    output_line(ctx, "%s", code);
} // emit_GLSL_dotprod

static void emit_GLSL_DP3(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_vec3(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_vec3(ctx, 1);
    emit_GLSL_dotprod(ctx, src0, src1, "");
} // emit_GLSL_DP3

static void emit_GLSL_DP4(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_full(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_full(ctx, 1);
    emit_GLSL_dotprod(ctx, src0, src1, "");
} // emit_GLSL_DP4

static void emit_GLSL_MIN(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx, "min(%s, %s)", src0, src1);
    output_line(ctx, "%s", code);
} // emit_GLSL_MIN

static void emit_GLSL_MAX(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx, "max(%s, %s)", src0, src1);
    output_line(ctx, "%s", code);
} // emit_GLSL_MAX

static void emit_GLSL_SLT(Context *ctx)
{
    const int vecsize = vecsize_from_writemask(ctx->dest_arg.writemask);
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = NULL;

    // float(bool) or vec(bvec) results in 0.0 or 1.0, like SLT wants.
    if (vecsize == 1)
        code = make_GLSL_destarg_assign(ctx, "float(%s < %s)", src0, src1);
    else
    {
        code = make_GLSL_destarg_assign(ctx, "vec%d(lessThan(%s, %s))",
                                        vecsize, src0, src1);
    } // else
    output_line(ctx, "%s", code);
} // emit_GLSL_SLT

static void emit_GLSL_SGE(Context *ctx)
{
    const int vecsize = vecsize_from_writemask(ctx->dest_arg.writemask);
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = NULL;

    // float(bool) or vec(bvec) results in 0.0 or 1.0, like SGE wants.
    if (vecsize == 1)
        code = make_GLSL_destarg_assign(ctx, "float(%s >= %s)", src0, src1);
    else
    {
        code = make_GLSL_destarg_assign(ctx, "vec%d(greaterThanEqual(%s, %s))",
                                        vecsize, src0, src1);
    } // else
    output_line(ctx, "%s", code);
} // emit_GLSL_SGE

static void emit_GLSL_EXP(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "exp2(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_EXP

static void emit_GLSL_LOG(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "log2(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_LOG

static void emit_GLSL_LIT_helper(Context *ctx)
{
    const char *maxp = "127.9961f"; // value from the dx9 reference.

    if (ctx->glsl_generated_lit_opcode)
        return;

    ctx->glsl_generated_lit_opcode = 1;

    push_output(ctx, &ctx->helpers);
    output_line(ctx, "const vec4 LIT(const vec4 src)");
    output_line(ctx, "{"); ctx->indent++;
    output_line(ctx,   "const float power = clamp(src.w, -%s, %s);",maxp,maxp);
    output_line(ctx,   "vec4 retval(1.0, 0.0, 0.0, 1.0)");
    output_line(ctx,   "if (src.x > 0.0) {"); ctx->indent++;
    output_line(ctx,     "retval.y = src.x;");
    output_line(ctx,     "if (src.y > 0.0) {"); ctx->indent++;
    output_line(ctx,       "retval.z = pow(src.y, power);"); ctx->indent--;
    output_line(ctx,     "}"); ctx->indent--;
    output_line(ctx,   "}");
    output_line(ctx,   "return retval;"); ctx->indent--;
    output_line(ctx, "}");
    output_blank_line(ctx);
    pop_output(ctx);
} // emit_GLSL_LIT_helper

static void emit_GLSL_LIT(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_full(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "LIT(%s)", src0);
    output_line(ctx, "%s", code);
    emit_GLSL_LIT_helper(ctx);
} // emit_GLSL_LIT

static void emit_GLSL_DST(Context *ctx)
{
    // !!! FIXME: needs to take ctx->dst_arg.writemask into account.
    const char *src0_y = make_GLSL_srcarg_string_y(ctx, 0);
    const char *src1_y = make_GLSL_srcarg_string_y(ctx, 1);
    const char *src0_z = make_GLSL_srcarg_string_z(ctx, 0);
    const char *src1_w = make_GLSL_srcarg_string_w(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx,
                            "vec4(1.0, %s * %s, %s, %s)",
                            src0_y, src1_y, src0_z, src1_w);
    output_line(ctx, "%s", code);
} // emit_GLSL_DST

static void emit_GLSL_LRP(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *src2 = make_GLSL_srcarg_string_masked(ctx, 2);
    const char *code = make_GLSL_destarg_assign(ctx, "mix(%s, %s, %s)", src2, src1, src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_LRP

static void emit_GLSL_FRC(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "fract(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_FRC

static void emit_GLSL_M4X4(Context *ctx)
{
    // !!! FIXME: d3d is row-major, glsl is column-major, I think.
    const char *src0 = make_GLSL_srcarg_string_full(ctx, 0);
    const char *row0 = make_GLSL_srcarg_string_full(ctx, 1);
    const char *row1 = make_GLSL_srcarg_string_full(ctx, 2);
    const char *row2 = make_GLSL_srcarg_string_full(ctx, 3);
    const char *row3 = make_GLSL_srcarg_string_full(ctx, 4);
    const char *code = make_GLSL_destarg_assign(ctx,
                    "vec4(dot(%s, %s), dot(%s, %s), dot(%s, %s), dot(%s, %s))",
                    src0, row0, src0, row1, src0, row2, src0, row3);
    output_line(ctx, "%s", code);
} // emit_GLSL_M4X4

static void emit_GLSL_M4X3(Context *ctx)
{
    // !!! FIXME: d3d is row-major, glsl is column-major, I think.
    const char *src0 = make_GLSL_srcarg_string_full(ctx, 0);
    const char *row0 = make_GLSL_srcarg_string_full(ctx, 1);
    const char *row1 = make_GLSL_srcarg_string_full(ctx, 2);
    const char *row2 = make_GLSL_srcarg_string_full(ctx, 3);
    const char *code = make_GLSL_destarg_assign(ctx,
                                "vec3(dot(%s, %s), dot(%s, %s), dot(%s, %s))",
                                src0, row0, src0, row1, src0, row2);
    output_line(ctx, "%s", code);
} // emit_GLSL_M4X3

static void emit_GLSL_M3X4(Context *ctx)
{
    // !!! FIXME: d3d is row-major, glsl is column-major, I think.
    const char *src0 = make_GLSL_srcarg_string_vec3(ctx, 0);
    const char *row0 = make_GLSL_srcarg_string_vec3(ctx, 1);
    const char *row1 = make_GLSL_srcarg_string_vec3(ctx, 2);
    const char *row2 = make_GLSL_srcarg_string_vec3(ctx, 3);
    const char *row3 = make_GLSL_srcarg_string_vec3(ctx, 4);

    const char *code = make_GLSL_destarg_assign(ctx,
                                "vec4(dot(%s, %s), dot(%s, %s), "
                                     "dot(%s, %s), dot(%s, %s))",
                                src0, row0, src0, row1,
                                src0, row2, src0, row3);
    output_line(ctx, "%s", code);
} // emit_GLSL_M3X4

static void emit_GLSL_M3X3(Context *ctx)
{
    // !!! FIXME: d3d is row-major, glsl is column-major, I think.
    const char *src0 = make_GLSL_srcarg_string_vec3(ctx, 0);
    const char *row0 = make_GLSL_srcarg_string_vec3(ctx, 1);
    const char *row1 = make_GLSL_srcarg_string_vec3(ctx, 2);
    const char *row2 = make_GLSL_srcarg_string_vec3(ctx, 3);
    const char *code = make_GLSL_destarg_assign(ctx,
                                "vec3(dot(%s, %s), dot(%s, %s), dot(%s, %s))",
                                src0, row0, src0, row1, src0, row2);
    output_line(ctx, "%s", code);
} // emit_GLSL_M3X3

static void emit_GLSL_M3X2(Context *ctx)
{
    // !!! FIXME: d3d is row-major, glsl is column-major, I think.
    const char *src0 = make_GLSL_srcarg_string_vec3(ctx, 0);
    const char *row0 = make_GLSL_srcarg_string_vec3(ctx, 1);
    const char *row1 = make_GLSL_srcarg_string_vec3(ctx, 2);

    const char *code = make_GLSL_destarg_assign(ctx,
                                "vec2(dot(%s, %s), dot(%s, %s))",
                                src0, row0, src0, row1);
    output_line(ctx, "%s", code);
} // emit_GLSL_M3X2

static void emit_GLSL_CALL(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    if (ctx->loops > 0)
        output_line(ctx, "%s(aL);", src0);
    else
        output_line(ctx, "%s();", src0);
} // emit_GLSL_CALL

static void emit_GLSL_CALLNZ(Context *ctx)
{
    // !!! FIXME: if src1 is a constbool that's true, we can remove the
    // !!! FIXME:  if. If it's false, we can make this a no-op.
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);

    if (ctx->loops > 0)
        output_line(ctx, "if (%s) { %s(aL); }", src1, src0);
    else
        output_line(ctx, "if (%s) { %s(); }", src1, src0);
} // emit_GLSL_CALLNZ

static void emit_GLSL_LOOP(Context *ctx)
{
    // !!! FIXME: swizzle?
    const char *varname = get_GLSL_srcarg_varname(ctx, 1);
    assert(ctx->source_args[0].regnum == 0);  // in case they add aL1 someday.
    output_line(ctx, "{");
    ctx->indent++;
    output_line(ctx, "const int aLend = %s.x + %s.y;", varname, varname);
    output_line(ctx, "for (int aL = %s.y; aL < aLend; aL += %s.z) {",
                varname, varname);
    ctx->indent++;
} // emit_GLSL_LOOP

static void emit_GLSL_RET(Context *ctx)
{
    // thankfully, the MSDN specs say a RET _has_ to end a function...no
    //  early returns. So if you hit one, you know you can safely close
    //  a high-level function.
    ctx->indent--;
    output_line(ctx, "}");
    output_blank_line(ctx);
    ctx->output = &ctx->subroutines;
} // emit_GLSL_RET

static void emit_GLSL_ENDLOOP(Context *ctx)
{
    ctx->indent--;
    output_line(ctx, "}");
    ctx->indent--;
    output_line(ctx, "}");
} // emit_GLSL_ENDLOOP

static void emit_GLSL_LABEL(Context *ctx)
{
    const char *labelstr = make_GLSL_srcarg_string_masked(ctx, 0);
    const int label = ctx->source_args[0].regnum;
    RegisterList *reg = reglist_find(&ctx->used_registers, REG_TYPE_LABEL, label);
    assert(ctx->output == &ctx->subroutines);  // not mainline, etc.
    assert(ctx->indent == 0);  // we shouldn't be in the middle of a function.

    // MSDN specs say CALL* has to come before the LABEL, so we know if we
    //  can ditch the entire function here as unused.
    if (reg == NULL)
        ctx->output = &ctx->ignore;  // Func not used. Parse, but don't output.

    // !!! FIXME: it would be nice if we could determine if a function is
    // !!! FIXME:  only called once and, if so, forcibly inline it.

    const char *uses_loopreg = ((reg) && (reg->misc == 1)) ? "int aL" : "";
    output_line(ctx, "void %s(%s)", labelstr, uses_loopreg);
    output_line(ctx, "{");
    ctx->indent++;
} // emit_GLSL_LABEL

static void emit_GLSL_DCL(Context *ctx)
{
    // no-op. We do this in our emit_attribute() and emit_uniform().
} // emit_GLSL_DCL

static void emit_GLSL_POW(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx, "pow(abs(%s), %s)", src0, src1);
    output_line(ctx, "%s", code);
} // emit_GLSL_POW

static void emit_GLSL_CRS(Context *ctx)
{
    // !!! FIXME: needs to take ctx->dst_arg.writemask into account.
    const char *src0 = make_GLSL_srcarg_string_vec3(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_vec3(ctx, 1);
    const char *code = make_GLSL_destarg_assign(ctx, "cross(%s, %s)", src0, src1);
    output_line(ctx, "%s", code);
} // emit_GLSL_CRS

static void emit_GLSL_SGN(Context *ctx)
{
    // (we don't need the temporary registers specified for the D3D opcode.)
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "sign(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_SGN

static void emit_GLSL_ABS(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "abs(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_ABS

static void emit_GLSL_NRM(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "normalize(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_NRM

static void emit_GLSL_SINCOS(Context *ctx)
{
    // we don't care about the temp registers that <= sm2 demands; ignore them.
    //  sm2 also talks about what components are left untouched vs. undefined,
    //  but we just leave those all untouched with GLSL write masks (which
    //  would fulfill the "undefined" requirement, too).
    const int mask = ctx->dest_arg.writemask;
    const char *src0 = make_GLSL_srcarg_string_scalar(ctx, 0);
    const char *code = NULL;

    if (writemask_x(mask))
        code = make_GLSL_destarg_assign(ctx, "cos(%s)", src0);
    else if (writemask_y(mask))
        code = make_GLSL_destarg_assign(ctx, "sin(%s)", src0);
    else if (writemask_xy(mask))
        code = make_GLSL_destarg_assign(ctx, "vec2(cos(%s), sin(%s))", src0, src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_SINCOS

static void emit_GLSL_REP(Context *ctx)
{
    // !!! FIXME:
    // msdn docs say legal loop values are 0 to 255. We can check DEFI values
    //  at parse time, but if they are pulling a value from a uniform, do
    //  we clamp here?
    // !!! FIXME: swizzle is legal here, right?
    const char *src0 = make_GLSL_srcarg_string_x(ctx, 0);
    const uint rep = (uint) ctx->reps;
    output_line(ctx, "for (int rep%u = 0; rep%u < %s; rep%u++) {",
                rep, rep, src0, rep);
    ctx->indent++;
} // emit_GLSL_REP

static void emit_GLSL_ENDREP(Context *ctx)
{
    ctx->indent--;
    output_line(ctx, "}");
} // emit_GLSL_ENDREP

static void emit_GLSL_IF(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_scalar(ctx, 0);
    output_line(ctx, "if (%s) {", src0);
    ctx->indent++;
} // emit_GLSL_IF

static void emit_GLSL_IFC(Context *ctx)
{
    const char *comp = get_GLSL_comparison_string_scalar(ctx);
    const char *src0 = make_GLSL_srcarg_string_scalar(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_scalar(ctx, 1);
    output_line(ctx, "if (%s %s %s) {", src0, comp, src1);
    ctx->indent++;
} // emit_GLSL_IFC

static void emit_GLSL_ELSE(Context *ctx)
{
    ctx->indent--;
    output_line(ctx, "} else {");
    ctx->indent++;
} // emit_GLSL_ELSE

static void emit_GLSL_ENDIF(Context *ctx)
{
    ctx->indent--;
    output_line(ctx, "}");
} // emit_GLSL_ENDIF

static void emit_GLSL_BREAK(Context *ctx)
{
    output_line(ctx, "break;");
} // emit_GLSL_BREAK

static void emit_GLSL_BREAKC(Context *ctx)
{
    const char *comp = get_GLSL_comparison_string_scalar(ctx);
    const char *src0 = make_GLSL_srcarg_string_scalar(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_scalar(ctx, 1);
    output_line(ctx, "if (%s %s %s) { break; }", src0, comp, src1);
} // emit_GLSL_BREAKC

static void emit_GLSL_MOVA(Context *ctx)
{
    const int vecsize = vecsize_from_writemask(ctx->dest_arg.writemask);
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);

    if (vecsize == 1)
    {
        const char *code = make_GLSL_destarg_assign(ctx,
                            "int(floor(abs(%s) + 0.5) * sign(%s))", src0, src0);
        output_line(ctx, "%s", code);
    } // if

    else
    {
        const char *code = make_GLSL_destarg_assign(ctx,
                            "ivec%d(floor(abs(%s) + vec%d(0.5)) * sign(%s))",
                            vecsize, src0, vecsize, src0);
        output_line(ctx, "%s", code);
    } // else
} // emit_GLSL_MOVA

static void emit_GLSL_DEFB(Context *ctx)
{
    const char *varname = get_GLSL_destarg_varname(ctx);
    push_output(ctx, &ctx->globals);
    output_line(ctx, "const bool %s = %s;",
                varname, ctx->dwords[0] ? "true" : "false");
    pop_output(ctx);
} // emit_GLSL_DEFB

static void emit_GLSL_DEFI(Context *ctx)
{
    const char *varname = get_GLSL_destarg_varname(ctx);
    const int32 *x = (const int32 *) ctx->dwords;
    push_output(ctx, &ctx->globals);
    output_line(ctx, "const ivec4 %s = ivec4(%d, %d, %d, %d);",
                varname, (int) x[0], (int) x[1], (int) x[2], (int) x[3]);
    pop_output(ctx);
} // emit_GLSL_DEFI

EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXCRD)

static void emit_GLSL_TEXKILL(Context *ctx)
{
    // !!! FIXME: can texkill swizzle?
    const char *dst = get_GLSL_destarg_varname(ctx);
    output_line(ctx, "if (any(lessThan(%s.xyz, vec3(0.0)))) discard;", dst);
} // emit_GLSL_TEXKILL

static void emit_GLSL_TEXLD(Context *ctx)
{
    // !!! FIXME: do non-RGBA textures map to same default values as D3D?

    if (!shader_version_atleast(ctx, 2, 0))
    {
        // ps_1_0 and ps_1_4 are both different, too!
        fail(ctx, "TEXLD <= Shader Model 2.0 unimplemented.");  // !!! FIXME
        return;
    } // if
    else
    {
        const SourceArgInfo *samp_arg = &ctx->source_args[1];
        RegisterList *sreg = reglist_find(&ctx->samplers, REG_TYPE_SAMPLER,
                                          samp_arg->regnum);
        const char *funcname = NULL;
        const char *src0 = NULL;
        const char *src1 = get_GLSL_srcarg_varname(ctx, 1); // !!! FIXME: SRC_MOD?

        if (sreg == NULL)
        {
            fail(ctx, "TEXLD using undeclared sampler");
            return;
        } // if

        switch ((const TextureType) sreg->index)
        {
            case TEXTURE_TYPE_2D:
                funcname = "texture2D";
                src0 = make_GLSL_srcarg_string_vec2(ctx, 0);
                break;
            case TEXTURE_TYPE_CUBE:
                funcname = "textureCube";
                src0 = make_GLSL_srcarg_string_vec3(ctx, 0);
                break;
            case TEXTURE_TYPE_VOLUME:
                funcname = "texture3D";
                src0 = make_GLSL_srcarg_string_vec3(ctx, 0);
                break;
            default:
                fail(ctx, "unknown texture type");
                return;
        } // switch

        assert(!scalar_register(samp_arg->regtype, samp_arg->regnum));
        char swiz_str[6] = { '\0' };
        make_GLSL_swizzle_string(swiz_str, sizeof (swiz_str),
                                 samp_arg->swizzle, ctx->dest_arg.writemask);

        const char *code = make_GLSL_destarg_assign(ctx,
                            "%s(%s, %s)%s", funcname, src1, src0, swiz_str);
        output_line(ctx, "%s", code);
    } // else
} // emit_GLSL_TEXLD

EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXBEM)  // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXBEML) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXREG2AR) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXREG2GB) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X2PAD) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X2TEX) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3PAD) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3TEX) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3SPEC) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3VSPEC) // !!! FIXME

static void emit_GLSL_EXPP(Context *ctx)
{
    // !!! FIXME: msdn's asm docs don't list this opcode, I'll have to check the driver documentation.
    emit_GLSL_EXP(ctx);  // I guess this is just partial precision EXP?
} // emit_GLSL_EXPP

static void emit_GLSL_LOGP(Context *ctx)
{
    // LOGP is just low-precision LOG, but we'll take the higher precision.
    emit_GLSL_LOG(ctx);
} // emit_GLSL_LOGP

// common code between CMP and CND.
static void emit_GLSL_comparison_operations(Context *ctx, const char *cmp)
{
    int i, j;
    DestArgInfo *dst = &ctx->dest_arg;
    const SourceArgInfo *srcarg0 = &ctx->source_args[0];
    const int origmask = dst->writemask;
    int used_swiz[4] = { 0, 0, 0, 0 };
    const int writemask[4] = { dst->writemask0, dst->writemask1,
                               dst->writemask2, dst->writemask3 };
    const int src0swiz[4] = { srcarg0->swizzle_x, srcarg0->swizzle_y,
                              srcarg0->swizzle_z, srcarg0->swizzle_w };

    for (i = 0; i < 4; i++)
    {
        int mask = (1 << i);

        if (!writemask[i]) continue;
        if (used_swiz[i]) continue;

        // This is a swizzle we haven't checked yet.
        used_swiz[i] = 1;

        // see if there are any other elements swizzled to match (.yyyy)
        for (j = i + 1; j < 4; j++)
        {
            if (!writemask[j]) continue;
            if (src0swiz[i] != src0swiz[j]) continue;
            mask |= (1 << j);
            used_swiz[j] = 1;
        } // for

        // okay, (mask) should be the writemask of swizzles we like.

        //return make_GLSL_srcarg_string(ctx, idx, (1 << 0));

        const char *src0 = make_GLSL_srcarg_string(ctx, 0, (1 << i));
        const char *src1 = make_GLSL_srcarg_string(ctx, 1, mask);
        const char *src2 = make_GLSL_srcarg_string(ctx, 2, mask);

        dst->writemask = mask;
        dst->writemask0 = ((mask >> 0) & 1);
        dst->writemask1 = ((mask >> 1) & 1);
        dst->writemask2 = ((mask >> 2) & 1);
        dst->writemask3 = ((mask >> 3) & 1);

        const char *code = make_GLSL_destarg_assign(ctx, "((%s %s) ? %s : %s)",
                                                    src0, cmp, src1, src2);
        dst->writemask = origmask;
        dst->writemask0 = ((origmask >> 0) & 1);
        dst->writemask1 = ((origmask >> 1) & 1);
        dst->writemask2 = ((origmask >> 2) & 1);
        dst->writemask3 = ((origmask >> 3) & 1);
        output_line(ctx, "%s", code);
    } // for
} // emit_GLSL_comparison_operations

static void emit_GLSL_CND(Context *ctx)
{
    emit_GLSL_comparison_operations(ctx, "> 0.5");
} // emit_GLSL_CND

static void emit_GLSL_DEF(Context *ctx)
{
    const char *varname = get_GLSL_destarg_varname(ctx);
    const float *val = (const float *) ctx->dwords; // !!! FIXME: could be int?
    char val0[32];
    char val1[32];
    char val2[32];
    char val3[32];
    floatstr(ctx, val0, sizeof (val0), val[0], 1);
    floatstr(ctx, val1, sizeof (val1), val[1], 1);
    floatstr(ctx, val2, sizeof (val2), val[2], 1);
    floatstr(ctx, val3, sizeof (val3), val[3], 1);

    push_output(ctx, &ctx->globals);
    output_line(ctx, "const vec4 %s = vec4(%s, %s, %s, %s);",
                varname, val0, val1, val2, val3);
    pop_output(ctx);
} // emit_GLSL_DEF

EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXREG2RGB) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXDP3TEX) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X2DEPTH) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXDP3) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3) // !!! FIXME
EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXDEPTH) // !!! FIXME

static void emit_GLSL_CMP(Context *ctx)
{
    emit_GLSL_comparison_operations(ctx, ">= 0.0");
} // emit_GLSL_CMP

EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(BEM) // !!! FIXME

static void emit_GLSL_DP2ADD(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_vec2(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_vec2(ctx, 1);
    const char *src2 = make_GLSL_srcarg_string_scalar(ctx, 2);
    char extra[64];
    snprintf(extra, sizeof (extra), " + %s", src2);
    emit_GLSL_dotprod(ctx, src0, src1, extra);
} // emit_GLSL_DP2ADD

static void emit_GLSL_DSX(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "dFdx(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_DSX

static void emit_GLSL_DSY(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *code = make_GLSL_destarg_assign(ctx, "dFdy(%s)", src0);
    output_line(ctx, "%s", code);
} // emit_GLSL_DSY

EMIT_GLSL_OPCODE_UNIMPLEMENTED_FUNC(TEXLDD) // !!! FIXME

static void emit_GLSL_SETP(Context *ctx)
{
    const int vecsize = vecsize_from_writemask(ctx->dest_arg.writemask);
    const char *src0 = make_GLSL_srcarg_string_masked(ctx, 0);
    const char *src1 = make_GLSL_srcarg_string_masked(ctx, 1);
    const char *code = NULL;

    // destination is always predicate register (which is type bvec4).
    if (vecsize == 1)
    {
        const char *comp = get_GLSL_comparison_string_scalar(ctx);
        code = make_GLSL_destarg_assign(ctx, "(%s %s %s)", src0, comp, src1);
    } // if
    else
    {
        const char *comp = get_GLSL_comparison_string_vector(ctx);
        code = make_GLSL_destarg_assign(ctx, "%s(%s, %s)", comp, src0, src1);
    } // else

    output_line(ctx, "%s", code);
} // emit_GLSL_SETP

static void emit_GLSL_TEXLDL(Context *ctx)
{
    // !!! FIXME: The spec says we can't use GLSL's texture*Lod() built-ins
    // !!! FIXME:  from fragment shaders for some inexplicable reason.
    // !!! FIXME:  For now, you'll just have to suffer with the potentially
    // !!! FIXME:  wrong mipmap until I can figure something out.
    emit_GLSL_TEXLD(ctx);
} // emit_GLSL_TEXLDL

static void emit_GLSL_BREAKP(Context *ctx)
{
    const char *src0 = make_GLSL_srcarg_string_scalar(ctx, 0);
    output_line(ctx, "if (%s) { break; }", src0);
} // emit_GLSL_BREAKP

static void emit_GLSL_RESERVED(Context *ctx)
{
    // do nothing; fails in the state machine.
} // emit_GLSL_RESERVED

#endif  // SUPPORT_PROFILE_GLSL


#if !SUPPORT_PROFILE_ARB1
#define PROFILE_EMITTER_ARB1(op)
#else
#undef AT_LEAST_ONE_PROFILE
#define AT_LEAST_ONE_PROFILE 1
#define PROFILE_EMITTER_ARB1(op) emit_ARB1_##op,

static const char *allocate_ARB1_scratch_reg_name(Context *ctx)
{
    char *buf = get_scratch_buffer(ctx);
    const int scratch = allocate_scratch_register(ctx);
    snprintf(buf, SCRATCH_BUFFER_SIZE, "scratch%d", scratch);
    return buf;
} // allocate_ARB1_scratch_reg_name

static const char *get_ARB1_branch_label_name(Context *ctx, int id)
{
    char *buf = get_scratch_buffer(ctx);
    snprintf(buf, SCRATCH_BUFFER_SIZE, "branch_label%d", id);
    return buf;
} // get_ARB1_branch_label_name

const char *get_ARB1_register_string(Context *ctx, RegisterType regtype,
                                     int regnum, char *regnum_str, int len)
{
    const char *retval = get_D3D_register_string(ctx, regtype, regnum,
                                                 regnum_str, len);
    if (retval == NULL)
    {
        fail(ctx, "Unknown D3D register type.");
        return "";
    } // if

    return retval;
} // get_ARB1_register_string

static const char *get_ARB1_varname(Context *ctx, RegisterType rt, int regnum)
{
    char regnum_str[16];
    const char *regtype_str = get_ARB1_register_string(ctx, rt, regnum,
                                              regnum_str, sizeof (regnum_str));

    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s%s", regtype_str, regnum_str);
    return retval;
} // get_ARB1_varname


static const char *get_ARB1_const_array_varname(Context *ctx, int base, int size)
{
    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "c_array_%d_%d", base, size);
    return retval;
} // get_ARB1_const_array_varname


static const char *make_ARB1_srcarg_string_in_buf(Context *ctx,
                                                  const SourceArgInfo *arg,
                                                  char *buf, size_t buflen)
{
    char regnum_str[16] = { '\0' };

    // !!! FIXME: use get_ARB1_varname() instead?
    const char *regtype_str = NULL;
    if (!arg->relative)
    {
        regtype_str = get_ARB1_register_string(ctx, arg->regtype,
                                               arg->regnum, regnum_str,
                                               sizeof (regnum_str));
    } // if

    const char *rel_lbracket = "";
    char rel_offset[32] = { '\0' };
    const char *rel_rbracket = "";
    char rel_swizzle[4] = { '\0' };
    const char *rel_regtype_str = "";
    if (arg->relative)
    {
        rel_regtype_str = get_ARB1_varname(ctx, arg->relative_regtype,
                                           arg->relative_regnum);

        rel_swizzle[0] = '.';
        rel_swizzle[1] = swizzle_channels[arg->relative_component];
        rel_swizzle[2] = '\0';

        if (!ctx->support_nv2)
        {
            // The address register in ARB1 only allows the '.x' component, so
            //  we need to load the component we need from a temp vector
            //  register into .x as needed.
            assert(arg->relative_regtype == REG_TYPE_ADDRESS);
            assert(arg->relative_regnum == 0);
            if (ctx->last_address_reg_component != arg->relative_component)
            {
                output_line(ctx, "ARL %s.x, addr%d.%c;", rel_regtype_str,
                            arg->relative_regnum,
                            swizzle_channels[arg->relative_component]);
                ctx->last_address_reg_component = arg->relative_component;
            } // if

            rel_swizzle[1] = 'x';
        } // if

        const int arrayidx = arg->relative_array->index;
        const int arraysize = arg->relative_array->count;
        const int offset = arg->regnum - arrayidx;
        assert(offset >= 0);

        regtype_str = get_ARB1_const_array_varname(ctx, arrayidx, arraysize);
        if (offset != 0)
            snprintf(rel_offset, sizeof (rel_offset), " + %d", offset);

        rel_lbracket = "[";
        rel_rbracket = "]";
    } // if

    // This is the source register with everything but swizzle and source mods.
    snprintf(buf, buflen, "%s%s%s%s%s%s%s", regtype_str, regnum_str,
             rel_lbracket, rel_regtype_str, rel_swizzle, rel_offset,
             rel_rbracket);

    // Some of the source mods need to generate instructions to a temp
    //  register, in which case we'll replace the register name.

    const char *premod_str = "";
    const char *postmod_str = "";
    switch (arg->src_mod)
    {
        case SRCMOD_NEGATE:
            premod_str = "-";
            break;

        case SRCMOD_BIASNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_BIAS:
            fail(ctx, "SRCMOD_BIAS currently unsupported in arb1");
            postmod_str = "_bias";
            break;

        case SRCMOD_SIGNNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_SIGN:
            fail(ctx, "SRCMOD_SIGN currently unsupported in arb1");
            postmod_str = "_bx2";
            break;

        case SRCMOD_COMPLEMENT:
            fail(ctx, "SRCMOD_COMPLEMENT currently unsupported in arb1");
            premod_str = "1-";
            break;

        case SRCMOD_X2NEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_X2:
            fail(ctx, "SRCMOD_X2 currently unsupported in arb1");
            postmod_str = "_x2";
            break;

        case SRCMOD_DZ:
            fail(ctx, "SRCMOD_DZ currently unsupported in arb1");
            postmod_str = "_dz";
            break;

        case SRCMOD_DW:
            fail(ctx, "SRCMOD_DW currently unsupported in arb1");
            postmod_str = "_dw";
            break;

        case SRCMOD_ABSNEGATE:
            premod_str = "-";
            // fall through.
        case SRCMOD_ABS:
            if (ctx->support_nv2)  // GL_NV_vertex_program2_option adds this.
            {
                premod_str = (arg->src_mod == SRCMOD_ABSNEGATE) ? "-|" : "|";
                postmod_str = "|";
            } // if
            else
            {
                regtype_str = allocate_ARB1_scratch_reg_name(ctx);
                regnum_str[0] = '\0'; // move value to scratch register.
                rel_lbracket = "";   // scratch register won't use array.
                rel_rbracket = "";
                rel_offset[0] = '\0';
                rel_swizzle[0] = '\0';
                rel_regtype_str = "";
                output_line(ctx, "ABS %s, %s;", regtype_str, buf);
            } // else
            break;

        case SRCMOD_NOT:
            fail(ctx, "SRCMOD_NOT currently unsupported in arb1");
            premod_str = "!";
            break;

        case SRCMOD_NONE:
        case SRCMOD_TOTAL:
             break;  // stop compiler whining.
    } // switch

    char swizzle_str[6];
    int i = 0;
    const int scalar = scalar_register(arg->regtype, arg->regnum);
    if (!scalar && !no_swizzle(arg->swizzle))
    {
        swizzle_str[i++] = '.';

        // .xxxx is the same as .x, but .xx is illegal...scalar or full!
        if (replicate_swizzle(arg->swizzle))
            swizzle_str[i++] = swizzle_channels[arg->swizzle_x];
        else
        {
            swizzle_str[i++] = swizzle_channels[arg->swizzle_x];
            swizzle_str[i++] = swizzle_channels[arg->swizzle_y];
            swizzle_str[i++] = swizzle_channels[arg->swizzle_z];
            swizzle_str[i++] = swizzle_channels[arg->swizzle_w];
        } // else
    } // if
    swizzle_str[i] = '\0';
    assert(i < sizeof (swizzle_str));

    snprintf(buf, buflen, "%s%s%s%s%s%s%s%s%s%s", premod_str,
             regtype_str, regnum_str, rel_lbracket,
             rel_regtype_str, rel_swizzle, rel_offset, rel_rbracket,
             swizzle_str, postmod_str);
    // !!! FIXME: make sure the scratch buffer was large enough.
    return buf;
} // make_ARB1_srcarg_string_in_buf

static const char *get_ARB1_destarg_varname(Context *ctx)
{
    const DestArgInfo *arg = &ctx->dest_arg;
    return get_ARB1_varname(ctx, arg->regtype, arg->regnum);
} // get_ARB1_destarg_varname

static const char *get_ARB1_srcarg_varname(Context *ctx, int idx)
{
    if (idx >= STATICARRAYLEN(ctx->source_args))
    {
        fail(ctx, "Too many source args");
        return "";
    } // if

    const SourceArgInfo *arg = &ctx->source_args[idx];
    return get_ARB1_varname(ctx, arg->regtype, arg->regnum);
} // get_ARB1_srcarg_varname


static const char *make_ARB1_destarg_string(Context *ctx)
{
    const DestArgInfo *arg = &ctx->dest_arg;

    const char *sat_str = "";
    // The "_SAT" modifier is only available in fragment shaders, but we'll
    //  fake it for them later in emit_ARB1_dest_modifiers() ...
    if ( (arg->result_mod & MOD_SATURATE) && (shader_is_pixel(ctx)) )
        sat_str = "_SAT";

    // no partial precision (MOD_PP), but that's okay.

    if (arg->result_mod & MOD_CENTROID)
    {
        fail(ctx, "dest register MOD_CENTROID currently unsupported in arb1");
        return "";
    } // if

    char regnum_str[16];
    const char *regtype_str = get_ARB1_register_string(ctx, arg->regtype,
                                                       arg->regnum, regnum_str,
                                                       sizeof (regnum_str));
    if (regtype_str == NULL)
    {
        fail(ctx, "Unknown destination register type.");
        return "";
    } // if

    char writemask_str[6];
    int i = 0;
    const int scalar = scalar_register(arg->regtype, arg->regnum);
    if (!scalar && !writemask_xyzw(arg->writemask))
    {
        writemask_str[i++] = '.';
        if (arg->writemask0) writemask_str[i++] = 'x';
        if (arg->writemask1) writemask_str[i++] = 'y';
        if (arg->writemask2) writemask_str[i++] = 'z';
        if (arg->writemask3) writemask_str[i++] = 'w';
    } // if
    writemask_str[i] = '\0';
    assert(i < sizeof (writemask_str));

    const char *pred_left = "";
    const char *pred_right = "";
    char pred[32] = { '\0' };
    if (ctx->predicated)
    {
        fail(ctx, "dest register predication currently unsupported in arb1");
        return "";
        pred_left = "(";
        pred_right = ") ";
        make_ARB1_srcarg_string_in_buf(ctx, &ctx->predicate_arg,
                                       pred, sizeof (pred));
    } // if

    char *retval = get_scratch_buffer(ctx);
    snprintf(retval, SCRATCH_BUFFER_SIZE, "%s %s%s%s", sat_str,
             regtype_str, regnum_str, writemask_str);
    // !!! FIXME: make sure the scratch buffer was large enough.
    return retval;
} // make_ARB1_destarg_string


static void emit_ARB1_dest_modifiers(Context *ctx)
{
    const DestArgInfo *arg = &ctx->dest_arg;

    if (arg->result_shift != 0x0)
    {
        const char *varname = get_ARB1_destarg_varname(ctx);
        const char *dst = make_ARB1_destarg_string(ctx);
        const char *multiplier = NULL;

        switch (arg->result_shift)
        {
            case 0x1: multiplier = "2.0"; break;
            case 0x2: multiplier = "4.0"; break;
            case 0x3: multiplier = "8.0"; break;
            case 0xD: multiplier = "0.125"; break;
            case 0xE: multiplier = "0.25"; break;
            case 0xF: multiplier = "0.5"; break;
        } // switch

        if (multiplier != NULL)
            output_line(ctx, "MUL%s, %s, %s;", dst, varname, multiplier);
    } // if

    if ( (arg->result_mod & MOD_SATURATE) && (!shader_is_pixel(ctx)) )
    {
        const char *varname = get_ARB1_destarg_varname(ctx);
        const char *dst = make_ARB1_destarg_string(ctx);
        // pixel shaders just use the "_SAT" modifier here, instead.
        output_line(ctx, "MIN%s, %s, 1.0;", dst, varname);
        output_line(ctx, "MAX%s, %s, 0.0;", dst, varname);
    } // if
} // emit_ARB1_dest_modifiers


static const char *make_ARB1_srcarg_string(Context *ctx, const int idx)
{
    if (idx >= STATICARRAYLEN(ctx->source_args))
    {
        fail(ctx, "Too many source args");
        return "";
    } // if

    const SourceArgInfo *arg = &ctx->source_args[idx];
    char *buf = get_scratch_buffer(ctx);
    return make_ARB1_srcarg_string_in_buf(ctx, arg, buf, SCRATCH_BUFFER_SIZE);
} // make_ARB1_srcarg_string

static void emit_ARB1_opcode_ds(Context *ctx, const char *opcode)
{
    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);
    output_line(ctx, "%s%s, %s;", opcode, dst, src0);
    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_opcode_ds

static void emit_ARB1_opcode_dss(Context *ctx, const char *opcode)
{
    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);
    const char *src1 = make_ARB1_srcarg_string(ctx, 1);
    output_line(ctx, "%s%s, %s, %s;", opcode, dst, src0, src1);
    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_opcode_dss

static void emit_ARB1_opcode_dsss(Context *ctx, const char *opcode)
{
    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);
    const char *src1 = make_ARB1_srcarg_string(ctx, 1);
    const char *src2 = make_ARB1_srcarg_string(ctx, 2);
    output_line(ctx, "%s%s, %s, %s, %s;", opcode, dst, src0, src1, src2);
    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_opcode_dsss


#define EMIT_ARB1_OPCODE_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_D_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode_d(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_S_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode_s(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_SS_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode_ss(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_DS_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode_ds(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_DSS_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode_dss(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_DSSS_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode_dsss(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_DSSSS_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        emit_ARB1_opcode_dssss(ctx, #op); \
    }
#define EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(op) \
    static void emit_ARB1_##op(Context *ctx) { \
        failf(ctx, #op " unimplemented in %s profile", ctx->profile->name); \
    }


static void emit_ARB1_start(Context *ctx, const char *profilestr)
{
    const char *shader_str = NULL;
    const char *shader_full_str = NULL;
    if (shader_is_vertex(ctx))
    {
        shader_str = "vp";
        shader_full_str = "vertex";
    } // if
    else if (shader_is_pixel(ctx))
    {
        shader_str = "fp";
        shader_full_str = "fragment";
    } // else if
    else
    {
        failf(ctx, "Shader type %u unsupported in this profile.",
              (uint) ctx->shader_type);
        return;
    } // if

    ctx->output = &ctx->globals;

    if (strcmp(profilestr, MOJOSHADER_PROFILE_ARB1) == 0)
        output_line(ctx, "!!ARB%s1.0", shader_str);

    else if (strcmp(profilestr, MOJOSHADER_PROFILE_NV2) == 0)
    {
        ctx->support_nv2 = 1;
        output_line(ctx, "!!ARB%s1.0", shader_str);
        output_line(ctx, "OPTION NV_%s_program2;", shader_full_str);
    } // else if

    else
    {
        failf(ctx, "Profile '%s' unsupported or unknown.", profilestr);
    } // else

    ctx->output = &ctx->mainline;
} // emit_ARB1_start

static void emit_ARB1_end(Context *ctx)
{
    output_line(ctx, "END");
} // emit_ARB1_end

static void emit_ARB1_phase(Context *ctx)
{
    // no-op in arb1.
} // emit_ARB1_phase

static void emit_ARB1_finalize(Context *ctx)
{
    int i;
    push_output(ctx, &ctx->globals);
    for (i = 0; i < ctx->max_scratch_registers; i++)
        output_line(ctx, "TEMP %s;", allocate_ARB1_scratch_reg_name(ctx));

    if ( (ctx->support_nv2) && (!shader_is_pixel(ctx)) )
    {
        // set up temps for nv2 REP/ENDREP emulation through branching.
        for (i = 0; i < ctx->max_reps; i++)
            output_line(ctx, "TEMP rep%d;", i);
    } // if

    pop_output(ctx);
    assert(ctx->scratch_registers == ctx->max_scratch_registers);
} // emit_ARB1_finalize

static void emit_ARB1_global(Context *ctx, RegisterType regtype, int regnum)
{
    // !!! FIXME: dependency on ARB1 profile.
    const char *varname = get_ARB1_varname(ctx, regtype, regnum);

    push_output(ctx, &ctx->globals);
    switch (regtype)
    {
        case REG_TYPE_ADDRESS:
            output_line(ctx, "ADDRESS %s;", varname);
            if (!ctx->support_nv2)  // nv2 has four-component address already.
                output_line(ctx, "TEMP addr%d;", regnum);
            break;
        //case REG_TYPE_PREDICATE:
        //    output_line(ctx, "bvec4 %s;", varname);
        //    break;
        case REG_TYPE_TEMP:
            output_line(ctx, "TEMP %s;", varname);
            break;
        //case REG_TYPE_LOOP:
        //    break; // no-op. We declare these in for loops at the moment.
        //case REG_TYPE_LABEL:
        //    break; // no-op. If we see it here, it means we optimized it out.
        default:
            fail(ctx, "BUG: we used a register we don't know how to define.");
            break;
    } // switch
    pop_output(ctx);
} // emit_ARB1_global

static void emit_ARB1_array(Context *ctx, int base, int size)
{
    const char *varname = get_ARB1_const_array_varname(ctx, base, size);
    push_output(ctx, &ctx->globals);
    output_line(ctx, "PARAM %s[%d] = { program.local[%d..%d] };", varname,
                size, base, (base + size) - 1);
    pop_output(ctx);
} // emit_ARB1_array

static void emit_ARB1_const_array(Context *ctx, const ConstantsList *clist,
                                  int base, int size)
{
    const char *varname = get_ARB1_const_array_varname(ctx, base, size);
    const int origscratch = ctx->scratchidx;
    int i;

    push_output(ctx, &ctx->globals);
    output_line(ctx, "PARAM %s[%d] = {", varname, size);
    ctx->indent++;

    for (i = 0; i < size; i++)
    {
        while (clist->constant.type != MOJOSHADER_UNIFORM_FLOAT)
            clist = clist->next;
        assert(clist->constant.index == (base + i));

        char val0[32];
        char val1[32];
        char val2[32];
        char val3[32];
        floatstr(ctx, val0, sizeof (val0), clist->constant.value.f[0], 1);
        floatstr(ctx, val1, sizeof (val1), clist->constant.value.f[1], 1);
        floatstr(ctx, val2, sizeof (val2), clist->constant.value.f[2], 1);
        floatstr(ctx, val3, sizeof (val3), clist->constant.value.f[3], 1);

        output_line(ctx, "{ %s, %s, %s, %s }%s", val0, val1, val2, val3,
                    (i < (size-1)) ? "," : "");

        ctx->scratchidx = origscratch;
        clist = clist->next;
    } // for

    ctx->indent--;
    output_line(ctx, "};");
    pop_output(ctx);
} // emit_ARB1_const_array

static void emit_ARB1_uniform(Context *ctx, RegisterType regtype, int regnum,
                              int arraybase, int arraysize)
{
    const char *varname = get_ARB1_varname(ctx, regtype, regnum);
    push_output(ctx, &ctx->globals);

    // !!! FIXME: this only works if you have no bool or int uniforms.
    if (regtype != REG_TYPE_CONST)
        fail(ctx, "BUG: non-float uniforms not supported in arb1 at the moment");
    else
        output_line(ctx, "PARAM %s = program.local[%d];", varname, regnum);

    pop_output(ctx);
} // emit_ARB1_uniform

static void emit_ARB1_sampler(Context *ctx, int stage, TextureType ttype)
{
    // this is a no-op...you don't predeclare samplers in arb1.
} // emit_ARB1_sampler

// !!! FIXME: a lot of cut-and-paste here from emit_GLSL_attribute().
static void emit_ARB1_attribute(Context *ctx, RegisterType regtype, int regnum,
                                MOJOSHADER_usage usage, int index, int wmask)
{
    // !!! FIXME: this function doesn't deal with write masks at all yet!
    const char *varname = get_ARB1_varname(ctx, regtype, regnum);
    const char *usage_str = NULL;
    const char *arrayleft = "";
    const char *arrayright = "";
    char index_str[16] = { '\0' };

    if (index != 0)  // !!! FIXME: a lot of these MUST be zero.
        snprintf(index_str, sizeof (index_str), "%u", (uint) index);

    if (shader_is_vertex(ctx))
    {
        // pre-vs3 output registers.
        // these don't ever happen in DCL opcodes, I think. Map to vs_3_*
        //  output registers.
        if (!shader_version_atleast(ctx, 3, 0))
        {
            if (regtype == REG_TYPE_RASTOUT)
            {
                regtype = REG_TYPE_OUTPUT;
                index = regnum;
                switch ((const RastOutType) regnum)
                {
                    case RASTOUT_TYPE_POSITION:
                        usage = MOJOSHADER_USAGE_POSITION;
                        break;
                    case RASTOUT_TYPE_FOG:
                        usage = MOJOSHADER_USAGE_FOG;
                        break;
                    case RASTOUT_TYPE_POINT_SIZE:
                        usage = MOJOSHADER_USAGE_POINTSIZE;
                        break;
                } // switch
            } // if

            else if (regtype == REG_TYPE_ATTROUT)
            {
                regtype = REG_TYPE_OUTPUT;
                usage = MOJOSHADER_USAGE_COLOR;
                index = regnum;
            } // else if

            else if (regtype == REG_TYPE_TEXCRDOUT)
            {
                regtype = REG_TYPE_OUTPUT;
                usage = MOJOSHADER_USAGE_TEXCOORD;
                index = regnum;
            } // else if
        } // if

        // to avoid limitations of various GL entry points for input
        // attributes (glSecondaryColorPointer() can only take 3 component
        // items, glVertexPointer() can't do GL_UNSIGNED_BYTE, many other
        // issues), we set up all inputs as generic vertex attributes, so we
        // can pass data in just about any form, and ignore the built-in GLSL
        // attributes like gl_SecondaryColor. Output needs to use the the
        // built-ins, though, but we don't have to worry about the GL entry
        // point limitations there.

        if (regtype == REG_TYPE_INPUT)
        {
            int attr = 0;  // POSITION0 _must_ be vertex.attrib[0]!
            if ((usage != MOJOSHADER_USAGE_POSITION) || (index != 0))
                attr = ++ctx->assigned_vertex_attributes;
            push_output(ctx, &ctx->globals);
            output_line(ctx, "ATTRIB %s = vertex.attrib[%d];", varname, attr);
            pop_output(ctx);
        } // if

        else if (regtype == REG_TYPE_OUTPUT)
        {
            switch (usage)
            {
                case MOJOSHADER_USAGE_POSITION:
                    usage_str = "result.position";
                    break;
                case MOJOSHADER_USAGE_POINTSIZE:
                    usage_str = "result.pointsize";
                    break;
                case MOJOSHADER_USAGE_COLOR:
                    index_str[0] = '\0';  // no explicit number.
                    if (index == 0)
                        usage_str = "result.color.primary";
                    else if (index == 1)
                        usage_str = "result.color.secondary";
                    break;
                case MOJOSHADER_USAGE_FOG:
                    usage_str = "result.fogcoord";
                    break;
                case MOJOSHADER_USAGE_TEXCOORD:
                    snprintf(index_str, sizeof (index_str), "%u", (uint) index);
                    usage_str = "result.texcoord";
                    arrayleft = "[";
                    arrayright = "]";
                    break;
                default:
                    // !!! FIXME: we need to deal with some more built-in varyings here.
                    break;
            } // switch

            // !!! FIXME: the #define is a little hacky, but it means we don't
            // !!! FIXME:  have to track these separately if this works.
            push_output(ctx, &ctx->globals);
            // no mapping to built-in var? Just make it a regular global, pray.
            if (usage_str == NULL)
                output_line(ctx, "TEMP %s;", varname);
            else
            {
                output_line(ctx, "OUTPUT %s = %s%s%s%s;", varname, usage_str,
                            arrayleft, index_str, arrayright);
            } // else
            pop_output(ctx);
        } // else if

        else
        {
            fail(ctx, "unknown vertex shader attribute register");
        } // else
    } // if

    else if (shader_is_pixel(ctx))
    {
        const char *paramtype_str = "ATTRIB";
        // samplers DCLs get handled in emit_ARB1_sampler().

        if (regtype == REG_TYPE_COLOROUT)
        {
            paramtype_str = "OUTPUT";
            usage_str = "result.color";
        } // if

        else if (regtype == REG_TYPE_DEPTHOUT)
        {
            paramtype_str = "OUTPUT";
            usage_str = "result.depth";
        } // else if

        // !!! FIXME: can you actualy have a texture register with COLOR usage?
        else if ((regtype == REG_TYPE_TEXTURE) || (regtype == REG_TYPE_INPUT))
        {
            if (usage == MOJOSHADER_USAGE_TEXCOORD)
            {
                snprintf(index_str, sizeof (index_str), "%u", (uint) index);
                usage_str = "fragment.texcoord";
                arrayleft = "[";
                arrayright = "]";
            } // if

            else if (usage == MOJOSHADER_USAGE_COLOR)
            {
                index_str[0] = '\0';  // no explicit number.
                if (index == 0)
                    usage_str = "fragment.color.primary";
                else if (index == 1)
                    usage_str = "fragment.color.secondary";
                else
                    fail(ctx, "unsupported color index");
            } // else if
        } // else if

        else if (regtype == REG_TYPE_MISCTYPE)
        {
            const MiscTypeType mt = (MiscTypeType) regnum;
            if (mt == MISCTYPE_TYPE_FACE)
            {
                fail(ctx, "Can't handle vFace in arb1 profile"); // !!! FIXME
                //push_output(ctx, &ctx->globals);
                //output_line(ctx, "float %s = gl_FrontFacing ? 1.0 : -1.0;",
                //            varname);
                //pop_output(ctx);
            } // if
            else if (mt == MISCTYPE_TYPE_POSITION)
            {
                index_str[0] = '\0';  // no explicit number.
                usage_str = "fragment.position";  // !!! FIXME: is this the same coord space as D3D?
            } // else if
            else
            {
                fail(ctx, "BUG: unhandled misc register");
            } // else
        } // else if

        else
        {
            fail(ctx, "unknown pixel shader attribute register");
        } // else

        if (usage_str != NULL)
        {
            push_output(ctx, &ctx->globals);
            output_line(ctx, "%s %s = %s%s%s%s;", paramtype_str, varname,
                        usage_str, arrayleft, index_str, arrayright);
            pop_output(ctx);
        } // if
    } // else if

    else
    {
        fail(ctx, "Unknown shader type");  // state machine should catch this.
    } // else
} // emit_ARB1_attribute

static void emit_ARB1_RESERVED(Context *ctx) { /* no-op. */ }

static void emit_ARB1_NOP(Context *ctx)
{
    // There is no NOP in arb1. Just don't output anything here.
} // emit_ARB1_NOP

EMIT_ARB1_OPCODE_DS_FUNC(MOV)
EMIT_ARB1_OPCODE_DSS_FUNC(ADD)
EMIT_ARB1_OPCODE_DSS_FUNC(SUB)
EMIT_ARB1_OPCODE_DSSS_FUNC(MAD)
EMIT_ARB1_OPCODE_DSS_FUNC(MUL)
EMIT_ARB1_OPCODE_DS_FUNC(RCP)
EMIT_ARB1_OPCODE_DS_FUNC(RSQ)
EMIT_ARB1_OPCODE_DSS_FUNC(DP3)
EMIT_ARB1_OPCODE_DSS_FUNC(DP4)
EMIT_ARB1_OPCODE_DSS_FUNC(MIN)
EMIT_ARB1_OPCODE_DSS_FUNC(MAX)
EMIT_ARB1_OPCODE_DSS_FUNC(SLT)
EMIT_ARB1_OPCODE_DSS_FUNC(SGE)

static void emit_ARB1_EXP(Context *ctx) { emit_ARB1_opcode_ds(ctx, "EX2"); }

static void emit_ARB1_LOG(Context *ctx)
{
    // we can optimize this to use nv2's |abs| construct in some cases.
    if ( (ctx->source_args[0].src_mod == SRCMOD_NONE) ||
         (ctx->source_args[0].src_mod == SRCMOD_ABSNEGATE) )
        ctx->source_args[0].src_mod = SRCMOD_ABS;

    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);

    if (ctx->source_args[0].src_mod == SRCMOD_ABS)
        output_line(ctx, "LG2%s, %s;", dst, src0);
    else
    {
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);
        output_line(ctx, "ABS %s, %s;", scratch, src0);
        output_line(ctx, "LG2%s, %s.x;", dst, scratch);
    } // else

    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_LOG

EMIT_ARB1_OPCODE_DS_FUNC(LIT)
EMIT_ARB1_OPCODE_DSS_FUNC(DST)

static void emit_ARB1_LRP(Context *ctx)
{
    if (shader_is_pixel(ctx))  // fragment shaders have a matching LRP opcode.
        emit_ARB1_opcode_dsss(ctx, "LRP");
    else
    {
        const char *dst = make_ARB1_destarg_string(ctx);
        const char *src0 = make_ARB1_srcarg_string(ctx, 0);
        const char *src1 = make_ARB1_srcarg_string(ctx, 1);
        const char *src2 = make_ARB1_srcarg_string(ctx, 2);
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);

        // LRP is: dest = src2 + src0 * (src1 - src2)
        output_line(ctx, "SUB %s, %s, %s;", scratch, src1, src2);
        output_line(ctx, "MAD%s, %s, %s, %s;", dst, scratch, src0, src2);
        emit_ARB1_dest_modifiers(ctx);
    } // else
} // emit_ARB1_LRP

EMIT_ARB1_OPCODE_DS_FUNC(FRC)

// !!! FIXME: these could be implemented with vector opcodes, but it looks
// !!! FIXME:  like the Microsoft HLSL compiler never generates matrix
// !!! FIXME:  operations for some reason.
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(M4X4)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(M4X3)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(M3X4)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(M3X3)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(M3X2)

static void emit_ARB1_CALL(Context *ctx)
{
    const char *labelstr = get_ARB1_srcarg_varname(ctx, 0);

    if (!ctx->support_nv2)  // no branching in stock ARB1.
    {
        failf(ctx, "branching unsupported in %s profile", ctx->profile->name);
        return;
    } // if

    output_line(ctx, "CAL %s;", labelstr);
} // emit_ARB1_CALL

static void emit_ARB1_CALLNZ(Context *ctx)
{
    // !!! FIXME: if src1 is a constbool that's true, we can remove the
    // !!! FIXME:  if. If it's false, we can make this a no-op.
    const char *labelstr = get_ARB1_srcarg_varname(ctx, 0);
    const char *src1 = make_ARB1_srcarg_string(ctx, 1);
    const char *scratch = allocate_ARB1_scratch_reg_name(ctx);

    if (!ctx->support_nv2)  // no branching in stock ARB1.
        failf(ctx, "branching unsupported in %s profile", ctx->profile->name);
    else
    {
        // !!! FIXME: double-check this.
        output_line(ctx, "MOVC %s, %s;", scratch, src1);
        output_line(ctx, "CAL %s (NE.x);", labelstr);
    } // else
} // emit_ARB1_CALLNZ


EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(LOOP)

static void emit_ARB1_RET(Context *ctx)
{
    // don't fail() if no nv2...maybe we're just ending the mainline?
    //  if we're ending a LABEL that had no CALL, this would all be written
    //  to ctx->ignore anyhow, so this should be "safe" ... arb1 profile will
    //  just end up throwing all this code out.
    if (ctx->support_nv2)  // no branching in stock ARB1.
        output_line(ctx, "RET;");
    ctx->output = &ctx->mainline;  // in case we were ignoring this function.
} // emit_ARB1_RET


EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(ENDLOOP)

static void emit_ARB1_LABEL(Context *ctx)
{
    if (!ctx->support_nv2)  // no branching in stock ARB1.
        return;  // don't fail()...maybe we never use it, but do fail in CALL.

    const char *labelstr = get_ARB1_srcarg_varname(ctx, 0);
    const int label = ctx->source_args[0].regnum;
    RegisterList *reg = reglist_find(&ctx->used_registers, REG_TYPE_LABEL, label);

    // MSDN specs say CALL* has to come before the LABEL, so we know if we
    //  can ditch the entire function here as unused.
    if (reg == NULL)
        ctx->output = &ctx->ignore;  // Func not used. Parse, but don't output.

    // !!! FIXME: it would be nice if we could determine if a function is
    // !!! FIXME:  only called once and, if so, forcibly inline it.

    //const char *uses_loopreg = ((reg) && (reg->misc == 1)) ? "int aL" : "";
    output_line(ctx, "%s:", labelstr);
} // emit_ARB1_LABEL


static void emit_ARB1_POW(Context *ctx)
{
    // we can optimize this to use nv2's |abs| construct in some cases.
    if ( (ctx->source_args[0].src_mod == SRCMOD_NONE) ||
         (ctx->source_args[0].src_mod == SRCMOD_ABSNEGATE) )
        ctx->source_args[0].src_mod = SRCMOD_ABS;

    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);
    const char *src1 = make_ARB1_srcarg_string(ctx, 1);

    if (ctx->source_args[0].src_mod == SRCMOD_ABS)
        output_line(ctx, "POW%s, %s, %s;", dst, src0, src1);
    else
    {
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);
        output_line(ctx, "ABS %s, %s;", scratch, src0);
        output_line(ctx, "POW%s, %s.x, %s;", dst, scratch, src1);
    } // else

    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_POW

static void emit_ARB1_CRS(Context *ctx) { emit_ARB1_opcode_dss(ctx, "XPD"); }

static void emit_ARB1_SGN(Context *ctx)
{
    if (ctx->support_nv2)
        emit_ARB1_opcode_ds(ctx, "SSG");
    else
    {
        const char *dst = make_ARB1_destarg_string(ctx);
        const char *src0 = make_ARB1_srcarg_string(ctx, 0);
        const char *scratch1 = allocate_ARB1_scratch_reg_name(ctx);
        const char *scratch2 = allocate_ARB1_scratch_reg_name(ctx);
        output_line(ctx, "SLT %s, %s, 0.0;", scratch1, src0);
        output_line(ctx, "SLT %s, -%s, 0.0;", scratch2, src0);
        output_line(ctx, "ADD%s -%s, %s;", dst, scratch1, scratch2);
        emit_ARB1_dest_modifiers(ctx);
    } // else
} // emit_ARB1_SGN

EMIT_ARB1_OPCODE_DS_FUNC(ABS)

static void emit_ARB1_NRM(Context *ctx)
{
    // nv2 fragment programs have a real NRM.
    if ( (ctx->support_nv2) && (shader_is_pixel(ctx)) )
        emit_ARB1_opcode_ds(ctx, "NRM");
    else
    {
        const char *dst = make_ARB1_destarg_string(ctx);
        const char *src0 = make_ARB1_srcarg_string(ctx, 0);
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);
        output_line(ctx, "DP3 %s.w, %s, %s;", scratch, src0, src0);
        output_line(ctx, "RSQ %s.w, %s.w;", scratch, scratch);
        output_line(ctx, "MUL%s, %s.w, %s;", dst, scratch, src0);
        emit_ARB1_dest_modifiers(ctx);
    } // else
} // emit_ARB1_NRM


static void emit_ARB1_SINCOS(Context *ctx)
{
    // we don't care about the temp registers that <= sm2 demands; ignore them.
    const int mask = ctx->dest_arg.writemask;

    // arb1 fragment shaders have sin/cos/sincos opcodes.
    if (shader_is_pixel(ctx))
    {
        const char *dst = make_ARB1_destarg_string(ctx);
        const char *src0 = make_ARB1_srcarg_string(ctx, 0);
        if (writemask_x(mask))
            output_line(ctx, "COS%s, %s;", dst, src0);
        else if (writemask_y(mask))
            output_line(ctx, "SIN%s, %s;", dst, src0);
        else if (writemask_xy(mask))
            output_line(ctx, "SCS%s, %s;", dst, src0);
    } // if

    // nv2+ shaders have sin and cos opcodes.
    else if (ctx->support_nv2)
    {
        const char *dst = get_ARB1_destarg_varname(ctx);
        const char *src0 = make_ARB1_srcarg_string(ctx, 0);
        if (writemask_x(mask))
            output_line(ctx, "COS %s.x, %s;", dst, src0);
        else if (writemask_y(mask))
            output_line(ctx, "SIN %s.y, %s;", dst, src0);
        else if (writemask_xy(mask))
        {
            output_line(ctx, "SIN %s.x, %s;", dst, src0);
            output_line(ctx, "COS %s.y, %s;", dst, src0);
        } // else if
    } // if

    else  // big nasty.
    {
        const char *dst = get_ARB1_destarg_varname(ctx);
        const char *src0 = get_ARB1_srcarg_varname(ctx, 0);
        const int need_sin = (writemask_x(mask) || writemask_xy(mask));
        const int need_cos = (writemask_y(mask) || writemask_xy(mask));
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);

        // These sin() and cos() approximations originally found here:
        //    http://www.devmaster.net/forums/showthread.php?t=5784
        //
        // const float B = 4.0f / M_PI;
        // const float C = -4.0f / (M_PI * M_PI);
        // float y = B * x + C * x * fabs(x);
        //
        // // optional better precision...
        // const float P = 0.225f;
        // y = P * (y * fabs(y) - y) + y;
        //
        //
        // That first thing can be reduced to:
        // const float y = ((1.2732395447351626861510701069801f * x) +
        //             ((-0.40528473456935108577551785283891f * x) * fabs(x)));

        if (need_sin)
        {
            // !!! FIXME: use SRCMOD_ABS here?
            output_line(ctx, "ABS %s.x, %s.x;", dst, src0);
            output_line(ctx, "MUL %s.x, %s.x, -0.40528473456935108577551785283891;", dst, dst);
            output_line(ctx, "MUL %s.x, %s.x, 1.2732395447351626861510701069801;", scratch, src0);
            output_line(ctx, "MAD %s.x, %s.x, %s.x, %s.x;", dst, dst, src0, scratch);
        } // if

        // cosine is sin(x + M_PI/2), but you have to wrap x to pi:
        //  if (x+(M_PI/2) > M_PI)
        //      x -= 2 * M_PI;
        //
        // which is...
        //  if (x+(1.57079637050628662109375) > 3.1415927410125732421875)
        //      x += -6.283185482025146484375;

        if (need_cos)
        {
            output_line(ctx, "ADD %s.x, %s.x, 1.57079637050628662109375;", scratch, src0);
            output_line(ctx, "SGE %s.y, %s.x, 3.1415927410125732421875;", scratch, scratch);
            output_line(ctx, "MAD %s.x, %s.y, -6.283185482025146484375, %s.x;", scratch, scratch, scratch);
            output_line(ctx, "ABS %s.x, %s.x;", dst, src0);
            output_line(ctx, "MUL %s.x, %s.x, -0.40528473456935108577551785283891;", dst, dst);
            output_line(ctx, "MUL %s.x, %s.x, 1.2732395447351626861510701069801;", scratch, src0);
            output_line(ctx, "MAD %s.y, %s.x, %s.x, %s.x;", dst, dst, src0, scratch);
        } // if
    } // else

    if (!isfail(ctx))
        emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_SINCOS


static void emit_ARB1_REP(Context *ctx)
{
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);

    // nv2 fragment programs have a real REP.
    if ( (ctx->support_nv2) && (shader_is_pixel(ctx)) )
        output_line(ctx, "REP %s;", src0);

    else if (ctx->support_nv2)
    {
        // no REP, but we can use branches.
        const int toplabel = allocate_branch_label(ctx);
        const int faillabel = allocate_branch_label(ctx);
        const char *topbranch = get_ARB1_branch_label_name(ctx, toplabel);
        const char *failbranch = get_ARB1_branch_label_name(ctx, faillabel);

        assert(ctx->branch_labels_stack_index < STATICARRAYLEN(ctx->branch_labels_stack)-1);
        ctx->branch_labels_stack[ctx->branch_labels_stack_index++] = toplabel;
        ctx->branch_labels_stack[ctx->branch_labels_stack_index++] = faillabel;

        char scratch[32];
        snprintf(scratch, sizeof (scratch), "rep%d", ctx->reps);
        output_line(ctx, "MOVC %s.x, %s;", scratch, src0);
        output_line(ctx, "BRA %s (LE.x);", failbranch);
        output_line(ctx, "%s:", topbranch);
    } // else if

    else  // stock ARB1 has no branching.
    {
        fail(ctx, "branching unsupported in this profile");
    } // else
} // emit_ARB1_REP


static void emit_ARB1_ENDREP(Context *ctx)
{
    // nv2 fragment programs have a real ENDREP.
    if ( (ctx->support_nv2) && (shader_is_pixel(ctx)) )
        output_line(ctx, "ENDREP;");

    else if (ctx->support_nv2)
    {
        // no ENDREP, but we can use branches.
        assert(ctx->branch_labels_stack_index >= 2);
        const int faillabel = ctx->branch_labels_stack[--ctx->branch_labels_stack_index];
        const int toplabel = ctx->branch_labels_stack[--ctx->branch_labels_stack_index];

        const char *topbranch = get_ARB1_branch_label_name(ctx, toplabel);
        const char *failbranch = get_ARB1_branch_label_name(ctx, faillabel);

        char scratch[32];
        snprintf(scratch, sizeof (scratch), "rep%d", ctx->reps);
        output_line(ctx, "SUBC %s.x, %s.x, 1.0;", scratch, scratch);
        output_line(ctx, "BRA %s (GT.x);", topbranch);
        output_line(ctx, "%s:", failbranch);
    } // else if

    else  // stock ARB1 has no branching.
    {
        fail(ctx, "branching unsupported in this profile");
    } // else
} // emit_ARB1_ENDREP


static void nv2_if(Context *ctx)
{
    // The condition code register MUST be set up before this!
    if (shader_is_pixel(ctx))  // nv2 fragment programs have a real IF.
        output_line(ctx, "IF EQ.x;");
    else
    {
        // there's no IF construct, but we can use a branch to a label.
        const int label = allocate_branch_label(ctx);
        const char *failbranch = get_ARB1_branch_label_name(ctx, label);

        assert(ctx->branch_labels_stack_index < STATICARRAYLEN(ctx->branch_labels_stack));
        ctx->branch_labels_stack[ctx->branch_labels_stack_index++] = label;

        output_line(ctx, "BRA %s (EQ.x);", failbranch);
    } // else
} // nv2_if


static void emit_ARB1_IF(Context *ctx)
{
    if (ctx->support_nv2)
    {
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);
        const char *src0 = get_ARB1_srcarg_varname(ctx, 0);
        output_line(ctx, "MOVC %s.x, %s;", scratch, src0);
        nv2_if(ctx);
    } // if

    else  // stock ARB1 has no branching.
    {
        failf(ctx, "branching unsupported in %s profile", ctx->profile->name);
    } // else
} // emit_ARB1_IF


static void emit_ARB1_ELSE(Context *ctx)
{
    // nv2 fragment programs have a real ELSE.
    if ( (ctx->support_nv2) && (shader_is_pixel(ctx)) )
        output_line(ctx, "ELSE;");

    else if (ctx->support_nv2)
    {
        // there's no ELSE construct, but we can use a branch to a label.
        assert(ctx->branch_labels_stack_index > 0);

        // At the end of the IF block, unconditionally jump to the ENDIF.
        const int endlabel = allocate_branch_label(ctx);
        output_line(ctx, "BRA %s;", get_ARB1_branch_label_name(ctx, endlabel));

        // Now mark the ELSE section with a lable.
        const int elselabel = ctx->branch_labels_stack[ctx->branch_labels_stack_index-1];
        output_line(ctx, "%s:", get_ARB1_branch_label_name(ctx, elselabel));

        // Replace the ELSE label with the ENDIF on the label stack.
        ctx->branch_labels_stack[ctx->branch_labels_stack_index-1] = endlabel;
    } // else if

    else  // stock ARB1 has no branching.
    {
        failf(ctx, "branching unsupported in %s profile", ctx->profile->name);
    } // else
} // emit_ARB1_ELSE


static void emit_ARB1_ENDIF(Context *ctx)
{
    // nv2 fragment programs have a real ENDIF.
    if ( (ctx->support_nv2) && (shader_is_pixel(ctx)) )
        output_line(ctx, "ENDIF;");

    else if (ctx->support_nv2)
    {
        // there's no ENDIF construct, but we can use a branch to a label.
        assert(ctx->branch_labels_stack_index > 0);
        const int endlabel = ctx->branch_labels_stack[--ctx->branch_labels_stack_index];
        output_line(ctx, "%s:", get_ARB1_branch_label_name(ctx, endlabel));
    } // if

    else  // stock ARB1 has no branching.
    {
        failf(ctx, "branching unsupported in %s profile", ctx->profile->name);
    } // else
} // emit_ARB1_ENDIF


static void emit_ARB1_BREAK(Context *ctx)
{
    // nv2 fragment programs have a real BREAK.
    if ( (ctx->support_nv2) && (shader_is_pixel(ctx)) )
        output_line(ctx, "BRK;");

    else if (ctx->support_nv2)
    {
        // no BREAK, but we can use branches.
        assert(ctx->branch_labels_stack_index >= 2);
        const int faillabel = ctx->branch_labels_stack[ctx->branch_labels_stack_index];
        const char *failbranch = get_ARB1_branch_label_name(ctx, faillabel);
        output_line(ctx, "BRA %s;", failbranch);
    } // else if

    else  // stock ARB1 has no branching.
    {
        failf(ctx, "branching unsupported in %s profile", ctx->profile->name);
    } // else
} // emit_ARB1_BREAK


static void emit_ARB1_MOVA(Context *ctx)
{
    // NV_vertex_program2_option and later can use the ARR opcode.
    if (ctx->support_nv2)
        emit_ARB1_opcode_ds(ctx, "ARR");
    else
    {
        const char *src0 = make_ARB1_srcarg_string(ctx, 0);
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);
        char addr[32];
        snprintf(addr, sizeof (addr), "addr%d", ctx->dest_arg.regnum);

        // !!! FIXME: we can optimize this if src_mod is ABS or ABSNEGATE.

        // ARL uses floor(), but D3D expects round-to-nearest.
        // There is probably a more efficient way to do this.
        if (shader_is_pixel(ctx))  // CMP only exists in fragment programs.  :/
            output_line(ctx, "CMP %s, %s, -1.0, 1.0;", scratch, src0);
        else
        {
            output_line(ctx, "SLT %s, %s, 0.0;", scratch, src0);
            output_line(ctx, "MAD %s, %s, -2.0, 1.0;", scratch, scratch);
        } // else

        output_line(ctx, "ABS %s, %s;", addr, src0);
        output_line(ctx, "ADD %s, %s, 0.5;", addr, addr);
        output_line(ctx, "FLR %s, %s;", addr, addr);
        output_line(ctx, "MUL %s, %s, %s;", addr, addr, scratch);

        // we don't handle these right now, since emit_ARB1_dest_modifiers(ctx)
        //  wants to look at dest_arg, not our temp register.
        assert(ctx->dest_arg.result_mod == 0);
        assert(ctx->dest_arg.result_shift == 0);

        // we assign to the actual address register as needed.
        ctx->last_address_reg_component = -1;
    } // else
} // emit_ARB1_MOVA

static void emit_ARB1_TEXKILL(Context *ctx)
{
    // !!! FIXME: d3d kills on xyz, arb1 kills on xyzw. Fix the swizzle!
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);
    output_line(ctx, "KIL %s;", src0);
} // emit_ARB1_TEXKILL

EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXBEM)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXBEML)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXREG2AR)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXREG2GB)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X2PAD)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X2TEX)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3PAD)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3TEX)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3SPEC)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3VSPEC)

static void emit_ARB1_EXPP(Context *ctx) { emit_ARB1_opcode_ds(ctx, "EXP"); }

static void emit_ARB1_LOGP(Context *ctx)
{
    // we can optimize this to use nv2's |abs| construct in some cases.
    if ( (ctx->source_args[0].src_mod == SRCMOD_NONE) ||
         (ctx->source_args[0].src_mod == SRCMOD_ABSNEGATE) )
        ctx->source_args[0].src_mod = SRCMOD_ABS;

    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);

    if (ctx->source_args[0].src_mod == SRCMOD_ABS)
        output_line(ctx, "LOG%s, %s;", dst, src0);
    else
    {
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);
        output_line(ctx, "ABS %s, %s;", scratch, src0);
        output_line(ctx, "LOG%s, %s.x;", dst, scratch);
    } // else

    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_LOGP

EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(CND)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXREG2RGB)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXDP3TEX)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X2DEPTH)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXDP3)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXM3X3)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXDEPTH)

static void emit_ARB1_CMP(Context *ctx)
{
    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);
    const char *src1 = make_ARB1_srcarg_string(ctx, 1);
    const char *src2 = make_ARB1_srcarg_string(ctx, 2);
    // D3D tests (src0 >= 0.0), but ARB1 tests (src0 < 0.0) ... so just
    //  switch src1 and src2 to get the same results.
    output_line(ctx, "CMP%s, %s, %s, %s;", dst, src0, src2, src1);
    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_CMP

EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(BEM)


static void emit_ARB1_DP2ADD(Context *ctx)
{
    const char *dst = make_ARB1_destarg_string(ctx);
    const char *src0 = make_ARB1_srcarg_string(ctx, 0);
    const char *src1 = make_ARB1_srcarg_string(ctx, 1);
    const char *src2 = make_ARB1_srcarg_string(ctx, 2);
    const char *scratch = allocate_ARB1_scratch_reg_name(ctx);

    // DP2ADD is:
    //  dest = src0.r * src1.r + src0.g * src1.g + src2.replicate_swizzle
    output_line(ctx, "MUL %s, %s, %s;", scratch, src0, src1);
    output_line(ctx, "ADD %s, %s.x, %s.y;", scratch, scratch, scratch);
    output_line(ctx, "ADD%s, %s.x, %s;", dst, scratch, src2);
    emit_ARB1_dest_modifiers(ctx);
} // emit_ARB1_DP2ADD


EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(DSX)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(DSY)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXLDD)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXLDL)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(BREAKP)
EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(BREAKC)

static void emit_ARB1_IFC(Context *ctx)
{
    if (ctx->support_nv2)
    {
        static const char *comps[] = {
            "", "SGTC", "SEQC", "SGEC", "SGTC", "SNEC", "SLEC"
        };

        if (ctx->instruction_controls >= STATICARRAYLEN(comps))
        {
            fail(ctx, "unknown comparison control");
            return;
        } // if

        const char *comp = comps[ctx->instruction_controls];
        const char *scratch = allocate_ARB1_scratch_reg_name(ctx);
        const char *src0 = get_ARB1_srcarg_varname(ctx, 0);
        const char *src1 = get_ARB1_srcarg_varname(ctx, 1);
        output_line(ctx, "%s %s.x, %s, %s;", comp, scratch, src0, src1);
        nv2_if(ctx);
    } // if

    else  // stock ARB1 has no branching.
    {
        failf(ctx, "branching unsupported in %s profile", ctx->profile->name);
    } // else
} // emit_ARB1_IFC


EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(SETP)

static void emit_ARB1_DEF(Context *ctx)
{
    const char *varname = get_ARB1_destarg_varname(ctx);
    const float *val = (const float *) ctx->dwords; // !!! FIXME: could be int?
    char val0[32];
    char val1[32];
    char val2[32];
    char val3[32];
    floatstr(ctx, val0, sizeof (val0), val[0], 1);
    floatstr(ctx, val1, sizeof (val1), val[1], 1);
    floatstr(ctx, val2, sizeof (val2), val[2], 1);
    floatstr(ctx, val3, sizeof (val3), val[3], 1);

    push_output(ctx, &ctx->globals);
    output_line(ctx, "PARAM %s = { %s, %s, %s, %s };",
                varname, val0, val1, val2, val3);
    pop_output(ctx);
} // emit_ARB1_DEF

static void emit_ARB1_DEFI(Context *ctx)
{
    const char *varname = get_ARB1_destarg_varname(ctx);
    const int32 *x = (const int32 *) ctx->dwords;
    push_output(ctx, &ctx->globals);
    output_line(ctx, "PARAM %s = { %d, %d, %d, %d };",
                varname, (int) x[0], (int) x[1], (int) x[2], (int) x[3]);
    pop_output(ctx);
} // emit_ARB1_DEFI

static void emit_ARB1_DEFB(Context *ctx)
{
    const char *varname = get_ARB1_destarg_varname(ctx);
    push_output(ctx, &ctx->globals);
    output_line(ctx, "PARAM %s = %d;", varname, ctx->dwords[0] ? 1 : 0);
    pop_output(ctx);
} // emit_ARB1_DEFB

static void emit_ARB1_DCL(Context *ctx)
{
    // no-op. We do this in our emit_attribute() and emit_uniform().
} // emit_ARB1_DCL

EMIT_ARB1_OPCODE_UNIMPLEMENTED_FUNC(TEXCRD)

static void emit_ARB1_TEXLD(Context *ctx)
{
    // !!! FIXME: do non-RGBA textures map to same default values as D3D?

    if (!shader_version_atleast(ctx, 2, 0))
    {
        // ps_1_0 and ps_1_4 are both different, too!
        fail(ctx, "TEXLD <= Shader Model 2.0 unimplemented.");  // !!! FIXME
        return;
    } // if
    else
    {
        const char *dst = make_ARB1_destarg_string(ctx);
        const SourceArgInfo *samp_arg = &ctx->source_args[1];
        RegisterList *sreg = reglist_find(&ctx->samplers, REG_TYPE_SAMPLER,
                                          samp_arg->regnum);
        const char *ttype = NULL;
        const char *src0 = make_ARB1_srcarg_string(ctx, 0);
        //const char *src1 = get_ARB1_srcarg_varname(ctx, 1); // !!! FIXME: SRC_MOD?

        // !!! FIXME: this should be in state_TEXLD, not in the arb1/glsl emitters.
        if (sreg == NULL)
        {
            fail(ctx, "TEXLD using undeclared sampler");
            return;
        } // if

        if (!no_swizzle(samp_arg->swizzle))
        {
            // !!! FIXME: does this ever actually happen?
            fail(ctx, "BUG: can't handle TEXLD with sampler swizzle at the moment");
        } // if

        switch ((const TextureType) sreg->index)
        {
            case TEXTURE_TYPE_2D: ttype = "2D"; break; // !!! FIXME: "RECT"?
            case TEXTURE_TYPE_CUBE: ttype = "CUBE"; break;
            case TEXTURE_TYPE_VOLUME: ttype = "3D"; break;
            default: fail(ctx, "unknown texture type"); return;
        } // switch

        output_line(ctx, "TEX%s, %s, texture[%d], %s;", dst, src0,
                    samp_arg->regnum, ttype);
    } // else
} // emit_ARB1_TEXLD

#endif  // SUPPORT_PROFILE_ARB1


#if !AT_LEAST_ONE_PROFILE
#error No profiles are supported. Fix your build.
#endif

#define DEFINE_PROFILE(prof) { \
    MOJOSHADER_PROFILE_##prof, \
    emit_##prof##_start, \
    emit_##prof##_end, \
    emit_##prof##_phase, \
    emit_##prof##_global, \
    emit_##prof##_array, \
    emit_##prof##_const_array, \
    emit_##prof##_uniform, \
    emit_##prof##_sampler, \
    emit_##prof##_attribute, \
    emit_##prof##_finalize, \
    get_##prof##_varname, \
    get_##prof##_const_array_varname, \
},

static const Profile profiles[] =
{
#if SUPPORT_PROFILE_D3D
    DEFINE_PROFILE(D3D)
#endif
#if SUPPORT_PROFILE_PASSTHROUGH
    DEFINE_PROFILE(PASSTHROUGH)
#endif
#if SUPPORT_PROFILE_GLSL
    DEFINE_PROFILE(GLSL)
#endif
#if SUPPORT_PROFILE_ARB1
    DEFINE_PROFILE(ARB1)
#endif
};

#undef DEFINE_PROFILE

// This is for profiles that extend other profiles...
static const struct { const char *from; const char *to; } profileMap[] =
{
    { MOJOSHADER_PROFILE_GLSL120, MOJOSHADER_PROFILE_GLSL },
    { MOJOSHADER_PROFILE_NV2, MOJOSHADER_PROFILE_ARB1 },
};


// The PROFILE_EMITTER_* items MUST be in the same order as profiles[]!
#define PROFILE_EMITTERS(op) { \
     PROFILE_EMITTER_D3D(op) \
     PROFILE_EMITTER_PASSTHROUGH(op) \
     PROFILE_EMITTER_GLSL(op) \
     PROFILE_EMITTER_ARB1(op) \
}

static int parse_destination_token(Context *ctx, DestArgInfo *info)
{
    // !!! FIXME: recheck against the spec for ranges (like RASTOUT values, etc).

    if (isfail(ctx))
        return FAIL;  // already failed elsewhere.

    if (ctx->tokencount == 0)
        return fail(ctx, "Out of tokens in destination parameter");

    const uint32 token = SWAP32(*(ctx->tokens));
    const int reserved1 = (int) ((token >> 14) & 0x3); // bits 14 through 15
    const int reserved2 = (int) ((token >> 31) & 0x1); // bit 31

    info->token = ctx->tokens;
    info->regnum = (int) (token & 0x7ff);  // bits 0 through 10
    info->relative = (int) ((token >> 13) & 0x1); // bit 13
    info->orig_writemask = (int) ((token >> 16) & 0xF); // bits 16 through 19
    info->result_mod = (int) ((token >> 20) & 0xF); // bits 20 through 23
    info->result_shift = (int) ((token >> 24) & 0xF); // bits 24 through 27      abc
    info->regtype = (RegisterType) (((token >> 28) & 0x7) | ((token >> 8) & 0x18));  // bits 28-30, 11-12

    int writemask;
    if (scalar_register(info->regtype, info->regnum))
        writemask = 0x1;  // just x.
    else
        writemask = info->orig_writemask;

    info->writemask = writemask;
    info->writemask0 = (int) ((writemask >> 0) & 0x1); // bit 16
    info->writemask1 = (int) ((writemask >> 1) & 0x1); // bit 17
    info->writemask2 = (int) ((writemask >> 2) & 0x1); // bit 18
    info->writemask3 = (int) ((writemask >> 3) & 0x1); // bit 19

    // all the REG_TYPE_CONSTx types are the same register type, it's just
    //  split up so its regnum can be > 2047 in the bytecode. Clean it up.
    if (info->regtype == REG_TYPE_CONST2)
    {
        info->regtype = REG_TYPE_CONST;
        info->regnum += 2048;
    } // else if
    else if (info->regtype == REG_TYPE_CONST3)
    {
        info->regtype = REG_TYPE_CONST;
        info->regnum += 4096;
    } // else if
    else if (info->regtype == REG_TYPE_CONST4)
    {
        info->regtype = REG_TYPE_CONST;
        info->regnum += 6144;
    } // else if

    ctx->tokens++;  // swallow token for now, for multiple calls in a row.
    ctx->tokencount--;  // swallow token for now, for multiple calls in a row.

    if (reserved1 != 0x0)
        return fail(ctx, "Reserved bit #1 in destination token must be zero");

    if (reserved2 != 0x1)
        return fail(ctx, "Reserved bit #2 in destination token must be one");

    if (info->relative)
    {
        if (!shader_is_vertex(ctx))
            return fail(ctx, "Relative addressing in non-vertex shader");
        else if (!shader_version_atleast(ctx, 3, 0))
            return fail(ctx, "Relative addressing in vertex shader version < 3.0");
        else if (!ctx->have_ctab)  // it's hard to do this efficiently without!
            return fail(ctx, "relative addressing unsupported without a CTAB");
        // !!! FIXME: I don't have a shader that has a relative dest currently.
        return fail(ctx, "Relative addressing of dest tokens is unsupported");
    } // if

    const int s = info->result_shift;
    if (s != 0)
    {
        if (!shader_is_pixel(ctx))
            return fail(ctx, "Result shift scale in non-pixel shader");
        else if (shader_version_atleast(ctx, 2, 0))
            return fail(ctx, "Result shift scale in pixel shader version >= 2.0");
        else if ( ! (((s >= 1) && (s <= 3)) || ((s >= 0xD) && (s <= 0xF))) )
            return fail(ctx, "Result shift scale isn't 1 to 3, or 13 to 15.");
    } // if

    if (info->result_mod & MOD_PP)  // Partial precision (pixel shaders only)
    {
        if (!shader_is_pixel(ctx))
            return fail(ctx, "Partial precision result mod in non-pixel shader");
    } // if

    if (info->result_mod & MOD_CENTROID)  // Centroid (pixel shaders only)
    {
        if (!shader_is_pixel(ctx))
            return fail(ctx, "Centroid result mod in non-pixel shader");
    } // if

    if ((info->regtype < 0) || (info->regtype > REG_TYPE_MAX))
        return fail(ctx, "Register type is out of range");

    // !!! FIXME: from msdn:
    //  "_sat cannot be used with instructions writing to output o# registers."
    // !!! FIXME: actually, just go over this page:
    //  http://msdn.microsoft.com/archive/default.asp?url=/archive/en-us/directx9_c/directx/graphics/reference/shaders/ps_instructionmodifiers.asp

    set_used_register(ctx, info->regtype, info->regnum);
    return 1;
} // parse_destination_token


static void determine_constants_arrays(Context *ctx)
{
    // Only process this stuff once. This is called after all DEF* opcodes
    //  could have been parsed.
    if (ctx->determined_constants_arrays)
        return;

    ctx->determined_constants_arrays = 1;

    if (ctx->constant_count <= 1)
        return;  // nothing to sort or group.

    // Sort the linked list into an array for easier tapdancing...
    ConstantsList **array = (ConstantsList **) alloca(sizeof (ConstantsList *) * (ctx->constant_count + 1));
    ConstantsList *item = ctx->constants;
    int i;

    for (i = 0; i < ctx->constant_count; i++)
    {
        if (item == NULL)
        {
            fail(ctx, "BUG: mismatched constant list and count");
            return;
        } // if

        array[i] = item;
        item = item->next;
    } // for

    array[ctx->constant_count] = NULL;

    // bubble sort ftw.
    int sorted;
    do
    {
        sorted = 1;
        for (i = 0; i < ctx->constant_count-1; i++)
        {
            if (array[i]->constant.index > array[i+1]->constant.index)
            {
                ConstantsList *tmp = array[i];
                array[i] = array[i+1];
                array[i+1] = tmp;
                sorted = 0;
            } // if
        } // for
    } while (!sorted);

    // okay, sorted. While we're here, let's redo the linked list in order...
    for (i = 0; i < ctx->constant_count; i++)
        array[i]->next = array[i+1];
    ctx->constants = array[0];

    // now figure out the groupings of constants and add to ctx->variables...
    int start = -1;
    int prev = -1;
    int count = 0;
    const int hi = ctx->constant_count;
    for (i = 0; i <= hi; i++)
    {
        if (array[i] && (array[i]->constant.type != MOJOSHADER_UNIFORM_FLOAT))
            continue;  // we only care about REG_TYPE_CONST for array groups.

        if (start == -1)
        {
            prev = start = i;  // first REG_TYPE_CONST we've seen. Mark it!
            continue;
        } // if

        // not a match (or last item in the array)...see if we had a
        //  contiguous set before this point...
        if ( (array[i]) && (array[i]->constant.index == (array[prev]->constant.index + 1)) )
            count++;
        else
        {
            if (count > 0)  // multiple constants in the set?
            {
                VariableList *var;
                var = (VariableList *) Malloc(ctx, sizeof (VariableList));
                if (var == NULL)
                    break;

                var->type = MOJOSHADER_UNIFORM_FLOAT;
                var->index = array[start]->constant.index;
                var->count = (array[prev]->constant.index - var->index) + 1;
                var->constant = array[start];
                var->used = 0;
                var->next = ctx->variables;
                ctx->variables = var;
            } // else

            start = i;   // set this as new start of sequence.
        } // if

        prev = i;
    } // for
} // determine_constants_arrays


static int parse_source_token(Context *ctx, SourceArgInfo *info)
{
    int retval = 1;

    if (isfail(ctx))
        return FAIL;  // already failed elsewhere.

    if (ctx->tokencount == 0)
        return fail(ctx, "Out of tokens in source parameter");

    const uint32 token = SWAP32(*(ctx->tokens));
    const int reserved1 = (int) ((token >> 14) & 0x3); // bits 14 through 15
    const int reserved2 = (int) ((token >> 31) & 0x1); // bit 31

    info->token = ctx->tokens;
    info->regnum = (int) (token & 0x7ff);  // bits 0 through 10
    info->relative = (int) ((token >> 13) & 0x1); // bit 13
    info->swizzle = (int) ((token >> 16) & 0xFF); // bits 16 through 23
    info->swizzle_x = (int) ((token >> 16) & 0x3); // bits 16 through 17
    info->swizzle_y = (int) ((token >> 18) & 0x3); // bits 18 through 19
    info->swizzle_z = (int) ((token >> 20) & 0x3); // bits 20 through 21
    info->swizzle_w = (int) ((token >> 22) & 0x3); // bits 22 through 23
    info->src_mod = (SourceMod) ((token >> 24) & 0xF); // bits 24 through 27
    info->regtype = (RegisterType) (((token >> 28) & 0x7) | ((token >> 8) & 0x18));  // bits 28-30, 11-12

    // all the REG_TYPE_CONSTx types are the same register type, it's just
    //  split up so its regnum can be > 2047 in the bytecode. Clean it up.
    if (info->regtype == REG_TYPE_CONST2)
    {
        info->regtype = REG_TYPE_CONST;
        info->regnum += 2048;
    } // else if
    else if (info->regtype == REG_TYPE_CONST3)
    {
        info->regtype = REG_TYPE_CONST;
        info->regnum += 4096;
    } // else if
    else if (info->regtype == REG_TYPE_CONST4)
    {
        info->regtype = REG_TYPE_CONST;
        info->regnum += 6144;
    } // else if

    ctx->tokens++;  // swallow token for now, for multiple calls in a row.
    ctx->tokencount--;  // swallow token for now, for multiple calls in a row.

    if (reserved1 != 0x0)
        return fail(ctx, "Reserved bits #1 in source token must be zero");

    if (reserved2 != 0x1)
        return fail(ctx, "Reserved bit #2 in source token must be one");

    if (info->relative)
    {
        if ( (shader_is_pixel(ctx)) && (!shader_version_atleast(ctx, 3, 0)) )
            return fail(ctx, "Relative addressing in pixel shader version < 3.0");

        if (ctx->tokencount == 0)
            return fail(ctx, "Out of tokens in relative source parameter");

        const uint32 reltoken = SWAP32(*(ctx->tokens));
        ctx->tokens++;  // swallow token for now, for multiple calls in a row.
        ctx->tokencount--;  // swallow token for now, for multiple calls in a row.

        const int relswiz  = (int) ((reltoken >> 16) & 0xFF);
        info->relative_component = relswiz & 0x3;
        info->relative_regnum = (int) (reltoken & 0x7ff);
        info->relative_regtype = (RegisterType)
                                    (((reltoken >> 28) & 0x7) |
                                    ((reltoken >> 8) & 0x18));

        if (((reltoken >> 31) & 0x1) == 0)
            return fail(ctx, "bit #31 in relative address must be set");

        if ((reltoken & 0xF00E000) != 0)  // usused bits.
            return fail(ctx, "relative address reserved bit must be zero");

        switch (info->relative_regtype)
        {
            case REG_TYPE_LOOP:
            case REG_TYPE_ADDRESS:
                break;
            default:
                return fail(ctx, "invalid register for relative address");
                break;
        } // switch

        if (info->relative_regnum != 0)  // true for now.
            return fail(ctx, "invalid register for relative address");

        if (info->regtype != REG_TYPE_CONST)
            return fail(ctx, "relative addressing of non-const register");

        if (!replicate_swizzle(relswiz))
            return fail(ctx, "relative address needs replicate swizzle");

        // figure out what array we're in...
        if (!ctx->have_ctab)  // it's hard to do this efficiently without!
            return fail(ctx, "relative addressing unsupported without a CTAB");

        determine_constants_arrays(ctx);

        VariableList *var;
        const int reltarget = info->regnum;
        for (var = ctx->variables; var != NULL; var = var->next)
        {
            const int lo = var->index;
            if ( (reltarget >= lo) && (reltarget < (lo + var->count)) )
                break;  // match!
        } // for

        if (var == NULL)
            return fail(ctx, "relative addressing of indeterminate array");

        var->used = 1;
        info->relative_array = var;
        set_used_register(ctx, info->relative_regtype, info->relative_regnum);
        retval++;
    } // if

    if ( info->src_mod >= SRCMOD_TOTAL )
        return fail(ctx, "Unknown source modifier");

    set_used_register(ctx, info->regtype, info->regnum);
    return retval;
} // parse_source_token


static int parse_predicated_token(Context *ctx)
{
    SourceArgInfo *arg = &ctx->predicate_arg;
    if (parse_source_token(ctx, arg) == FAIL)
        return FAIL;
    else if (arg->regtype != REG_TYPE_PREDICATE)
        return fail(ctx, "Predicated instruction but not predicate register!");
    else if ((arg->src_mod != SRCMOD_NONE) && (arg->src_mod != SRCMOD_NOT))
        return fail(ctx, "Predicated instruction register is not NONE or NOT");
    else if ( !no_swizzle(arg->swizzle) && !replicate_swizzle(arg->swizzle) )
        return fail(ctx, "Predicated instruction register has wrong swizzle");
    else if (arg->relative)  // I'm pretty sure this is illegal...?
        return fail(ctx, "relative addressing in predicated token");

    return 1;
} // parse_predicated_token


static int parse_args_NULL(Context *ctx)
{
    return (isfail(ctx) ? FAIL : 1);
} // parse_args_NULL


static int parse_args_DEF(Context *ctx)
{
    if (parse_destination_token(ctx, &ctx->dest_arg) == FAIL)
        return FAIL;

    if (ctx->dest_arg.relative)  // I'm pretty sure this is illegal...?
        return fail(ctx, "relative addressing in DEFB");

    ctx->dwords[0] = SWAP32(ctx->tokens[0]);
    ctx->dwords[1] = SWAP32(ctx->tokens[1]);
    ctx->dwords[2] = SWAP32(ctx->tokens[2]);
    ctx->dwords[3] = SWAP32(ctx->tokens[3]);

    return 6;
} // parse_args_DEF


static int parse_args_DEFB(Context *ctx)
{
    if (parse_destination_token(ctx, &ctx->dest_arg) == FAIL)
        return FAIL;

    if (ctx->dest_arg.relative)  // I'm pretty sure this is illegal...?
        return fail(ctx, "relative addressing in DEFB");

    ctx->dwords[0] = *(ctx->tokens) ? 1 : 0;

    return 3;
} // parse_args_DEFB


static int valid_texture_type(const uint32 ttype)
{
    switch ((const TextureType) ttype)
    {
        case TEXTURE_TYPE_2D:
        case TEXTURE_TYPE_CUBE:
        case TEXTURE_TYPE_VOLUME:
            return 1;  // it's okay.
    } // switch

    return 0;
} // valid_texture_type


// !!! FIXME: this function is kind of a mess.
static int parse_args_DCL(Context *ctx)
{
    int unsupported = 0;
    const uint32 token = SWAP32(*(ctx->tokens));
    const int reserved1 = (int) ((token >> 31) & 0x1); // bit 31
    uint32 reserved_mask = 0x00000000;

    if (reserved1 != 0x1)
        return fail(ctx, "Bit #31 in DCL token must be one");

    ctx->tokens++;
    ctx->tokencount--;
    if (parse_destination_token(ctx, &ctx->dest_arg) == FAIL)
        return FAIL;

    if (ctx->dest_arg.relative)  // I'm pretty sure this is illegal...?
        return fail(ctx, "relative addressing in DCL");

    const RegisterType regtype = ctx->dest_arg.regtype;
    const int regnum = ctx->dest_arg.regnum;
    if ( (shader_is_pixel(ctx)) && (shader_version_atleast(ctx, 3, 0)) )
    {
        if (regtype == REG_TYPE_INPUT)
        {
            const uint32 usage = (token & 0xF);
            const uint32 index = ((token >> 16) & 0xF);
            reserved_mask = 0x7FF0FFE0;
            ctx->dwords[0] = usage;
            ctx->dwords[1] = index;
        } // if

        else if (regtype == REG_TYPE_MISCTYPE)
        {
            const MiscTypeType mt = (MiscTypeType) regnum;
            if (mt == MISCTYPE_TYPE_POSITION)
                reserved_mask = 0x7FFFFFFF;
            else if (mt == MISCTYPE_TYPE_FACE)
            {
                reserved_mask = 0x7FFFFFFF;
                if (!writemask_xyzw(ctx->dest_arg.orig_writemask))
                    return fail(ctx, "DCL face writemask must be full");
                else if (ctx->dest_arg.result_mod != 0)
                    return fail(ctx, "DCL face result modifier must be zero");
                else if (ctx->dest_arg.result_shift != 0)
                    return fail(ctx, "DCL face shift scale must be zero");
            } // else if
            else
            {
                unsupported = 1;
            } // else

            ctx->dwords[0] = (uint32) MOJOSHADER_USAGE_UNKNOWN;
            ctx->dwords[1] = 0;
        } // else if

        else if (regtype == REG_TYPE_TEXTURE)
        {
            const uint32 usage = (token & 0xF);
            const uint32 index = ((token >> 16) & 0xF);
            if (usage == MOJOSHADER_USAGE_TEXCOORD)
            {
                if (index > 7)
                    return fail(ctx, "DCL texcoord usage must have 0-7 index");
            } // if
            else if (usage == MOJOSHADER_USAGE_COLOR)
            {
                if (index != 0)
                    return fail(ctx, "DCL color usage must have 0 index");
            } // else if
            else
            {
                return fail(ctx, "Invalid DCL texture usage");
            } // else

            reserved_mask = 0x7FF0FFE0;
            ctx->dwords[0] = usage;
            ctx->dwords[1] = index;
        } // else if

        else if (regtype == REG_TYPE_SAMPLER)
        {
            const uint32 ttype = ((token >> 27) & 0xF);
            if (!valid_texture_type(ttype))
                return fail(ctx, "unknown sampler texture type");
            reserved_mask = 0x7FFFFFF;
            ctx->dwords[0] = ttype;
        } // else if

        else
        {
            unsupported = 1;
        } // else
    } // if

    else if ( (shader_is_pixel(ctx)) && (shader_version_atleast(ctx, 2, 0)) )
    {
        if (regtype == REG_TYPE_INPUT)
        {
            ctx->dwords[0] = (uint32) MOJOSHADER_USAGE_COLOR;
            ctx->dwords[1] = regnum;
            reserved_mask = 0x7FFFFFFF;
        } // if
        else if (regtype == REG_TYPE_TEXTURE)
        {
            ctx->dwords[0] = (uint32) MOJOSHADER_USAGE_TEXCOORD;
            ctx->dwords[1] = regnum;
            reserved_mask = 0x7FFFFFFF;
        } // else if
        else if (regtype == REG_TYPE_SAMPLER)
        {
            const uint32 ttype = ((token >> 27) & 0xF);
            if (!valid_texture_type(ttype))
                return fail(ctx, "unknown sampler texture type");
            reserved_mask = 0x7FFFFFF;
            ctx->dwords[0] = ttype;
        } // else if
        else
        {
            unsupported = 1;
        } // else
    } // if

    else if ( (shader_is_vertex(ctx)) && (shader_version_atleast(ctx, 3, 0)) )
    {
        if ((regtype == REG_TYPE_INPUT) || (regtype == REG_TYPE_OUTPUT))
        {
            const uint32 usage = (token & 0xF);
            const uint32 index = ((token >> 16) & 0xF);
            reserved_mask = 0x7FF0FFE0;
            ctx->dwords[0] = usage;
            ctx->dwords[1] = index;
        } // if
        else
        {
            unsupported = 1;
        } // else
    } // else if

    else if ( (shader_is_vertex(ctx)) && (shader_version_atleast(ctx, 2, 0)) )
    {
        if (regtype == REG_TYPE_INPUT)
        {
            const uint32 usage = (token & 0xF);
            const uint32 index = ((token >> 16) & 0xF);
            reserved_mask = 0x7FF0FFE0;
            ctx->dwords[0] = usage;
            ctx->dwords[1] = index;
        } // if
        else
        {
            unsupported = 1;
        } // else
    } // else if

    else
    {
        unsupported = 1;
    } // else

    if (unsupported)
        return fail(ctx, "invalid DCL register type for this shader model");

    if ((token & reserved_mask) != 0)
        return fail(ctx, "reserved bits in DCL dword aren't zero");

    return 3;
} // parse_args_DCL


static int parse_args_D(Context *ctx)
{
    int retval = 1;
    retval += parse_destination_token(ctx, &ctx->dest_arg);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_D


static int parse_args_S(Context *ctx)
{
    int retval = 1;
    retval += parse_source_token(ctx, &ctx->source_args[0]);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_S


static int parse_args_SS(Context *ctx)
{
    int retval = 1;
    retval += parse_source_token(ctx, &ctx->source_args[0]);
    retval += parse_source_token(ctx, &ctx->source_args[1]);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_SS


static int parse_args_DS(Context *ctx)
{
    int retval = 1;
    retval += parse_destination_token(ctx, &ctx->dest_arg);
    retval += parse_source_token(ctx, &ctx->source_args[0]);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_DS


static int parse_args_DSS(Context *ctx)
{
    int retval = 1;
    retval += parse_destination_token(ctx, &ctx->dest_arg);
    retval += parse_source_token(ctx, &ctx->source_args[0]);
    retval += parse_source_token(ctx, &ctx->source_args[1]);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_DSS


static int parse_args_DSSS(Context *ctx)
{
    int retval = 1;
    retval += parse_destination_token(ctx, &ctx->dest_arg);
    retval += parse_source_token(ctx, &ctx->source_args[0]);
    retval += parse_source_token(ctx, &ctx->source_args[1]);
    retval += parse_source_token(ctx, &ctx->source_args[2]);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_DSSS


static int parse_args_DSSSS(Context *ctx)
{
    int retval = 1;
    retval += parse_destination_token(ctx, &ctx->dest_arg);
    retval += parse_source_token(ctx, &ctx->source_args[0]);
    retval += parse_source_token(ctx, &ctx->source_args[1]);
    retval += parse_source_token(ctx, &ctx->source_args[2]);
    retval += parse_source_token(ctx, &ctx->source_args[3]);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_DSSSS


static int parse_args_SINCOS(Context *ctx)
{
    // this opcode needs extra registers for sm2 and lower.
    if (!shader_version_atleast(ctx, 3, 0))
        return parse_args_DSSS(ctx);
    return parse_args_DS(ctx);
} // parse_args_SINCOS


static int parse_args_TEXCRD(Context *ctx)
{
    // added extra register in ps_1_4.
    if (shader_version_atleast(ctx, 1, 4))
        return parse_args_DS(ctx);
    return parse_args_D(ctx);
} // parse_args_TEXCRD


static int parse_args_TEXLD(Context *ctx)
{
    // different registers in px_1_3, ps_1_4, and ps_2_0!
    if (shader_version_atleast(ctx, 2, 0))
        return parse_args_DSS(ctx);
    else if (shader_version_atleast(ctx, 1, 4))
        return parse_args_DS(ctx);
    return parse_args_D(ctx);
} // parse_args_TEXLD


// State machine functions...

static ConstantsList *alloc_constant_listitem(Context *ctx)
{
    ConstantsList *item = (ConstantsList *) Malloc(ctx, sizeof (ConstantsList));
    if (item == NULL)
        return NULL;

    memset(&item->constant, '\0', sizeof (MOJOSHADER_constant));
    item->next = ctx->constants;
    ctx->constants = item;
    ctx->constant_count++;

    return item;
} // alloc_constant_listitem

static void state_DEF(Context *ctx)
{
    const RegisterType regtype = ctx->dest_arg.regtype;
    const int regnum = ctx->dest_arg.regnum;

    // !!! FIXME: fail if same register is defined twice.

    if (ctx->instruction_count != 0)
        fail(ctx, "DEF token must come before any instructions");
    else if (regtype != REG_TYPE_CONST)
        fail(ctx, "DEF token using invalid register");
    else
    {
        ConstantsList *item = alloc_constant_listitem(ctx);
        item->constant.index = regnum;
        item->constant.type = MOJOSHADER_UNIFORM_FLOAT;
        memcpy(item->constant.value.f, ctx->dwords,
               sizeof (item->constant.value.f));
        set_defined_register(ctx, regtype, regnum);
    } // else
} // state_DEF

static void state_DEFI(Context *ctx)
{
    const RegisterType regtype = ctx->dest_arg.regtype;
    const int regnum = ctx->dest_arg.regnum;

    // !!! FIXME: fail if same register is defined twice.

    if (ctx->instruction_count != 0)
        fail(ctx, "DEFI token must come before any instructions");
    else if (regtype != REG_TYPE_CONSTINT)
        fail(ctx, "DEFI token using invalid register");
    else
    {
        ConstantsList *item = alloc_constant_listitem(ctx);
        item->constant.index = regnum;
        item->constant.type = MOJOSHADER_UNIFORM_INT;
        memcpy(item->constant.value.i, ctx->dwords,
               sizeof (item->constant.value.i));

        set_defined_register(ctx, regtype, regnum);
    } // else
} // state_DEFI

static void state_DEFB(Context *ctx)
{
    const RegisterType regtype = ctx->dest_arg.regtype;
    const int regnum = ctx->dest_arg.regnum;

    // !!! FIXME: fail if same register is defined twice.

    if (ctx->instruction_count != 0)
        fail(ctx, "DEFB token must come before any instructions");
    else if (regtype != REG_TYPE_CONSTBOOL)
        fail(ctx, "DEFB token using invalid register");
    else
    {
        ConstantsList *item = alloc_constant_listitem(ctx);
        item->constant.index = regnum;
        item->constant.type = MOJOSHADER_UNIFORM_BOOL;
        item->constant.value.b = ctx->dwords[0] ? 1 : 0;
        set_defined_register(ctx, regtype, regnum);
    } // else
} // state_DEFB

static void state_DCL(Context *ctx)
{
    const DestArgInfo *arg = &ctx->dest_arg;
    const RegisterType regtype = arg->regtype;
    const int regnum = arg->regnum;
    const int wmask = arg->writemask;

    // parse_args_DCL() does a lot of state checking before we get here.

    // !!! FIXME: apparently vs_3_0 can use sampler registers now.
    // !!! FIXME:  (but only s0 through s3, not all 16 of them.)

    if (ctx->instruction_count != 0)
        fail(ctx, "DCL token must come before any instructions");

    else if (shader_is_vertex(ctx))
    {
        const MOJOSHADER_usage usage = (const MOJOSHADER_usage) ctx->dwords[0];
        const int index = ctx->dwords[1];
        if (usage >= MOJOSHADER_USAGE_TOTAL)
        {
            fail(ctx, "unknown DCL usage");
            return;
        } // if
        add_attribute_register(ctx, regtype, regnum, usage, index, wmask);
    } // if

    else if (shader_is_pixel(ctx))
    {
        if (regtype == REG_TYPE_SAMPLER)
            add_sampler(ctx, regtype, regnum, (TextureType) ctx->dwords[0]);
        else
        {
            const MOJOSHADER_usage usage = (MOJOSHADER_usage) ctx->dwords[0];
            const int index = ctx->dwords[1];
            add_attribute_register(ctx, regtype, regnum, usage, index, wmask);
        } // else
    } // else if

    else
    {
        fail(ctx, "unsupported shader type."); // should be caught elsewhere.
        return;
    } // else

    set_defined_register(ctx, regtype, regnum);
} // state_DCL

static void state_TEXCRD(Context *ctx)
{
    if (shader_version_atleast(ctx, 2, 0))
        fail(ctx, "TEXCRD in Shader Model >= 2.0");  // apparently removed.
} // state_TEXCRD

static void state_FRC(Context *ctx)
{
    const DestArgInfo *dst = &ctx->dest_arg;

    if (dst->result_mod & MOD_SATURATE)  // according to msdn...
        fail(ctx, "FRC destination can't use saturate modifier");

    else if (!shader_version_atleast(ctx, 2, 0))
    {
        if (!writemask_y(dst->writemask) && !writemask_xy(dst->writemask))
            fail(ctx, "FRC writemask must be .y or .xy for shader model 1.x");
    } // else if
} // state_FRC


// replicate the matrix registers to source args. The D3D profile will
//  only use the one legitimate argument, but this saves other profiles
//  from having to build this.
static void srcarg_matrix_replicate(Context *ctx, const int idx,
                                       const int rows)
{
    int i;
    SourceArgInfo *src = &ctx->source_args[idx];
    SourceArgInfo *dst = &ctx->source_args[idx+1];
    for (i = 0; i < (rows-1); i++, dst++)
    {
        memcpy(dst, src, sizeof (SourceArgInfo));
        dst->regnum += (i + 1);
        set_used_register(ctx, dst->regtype, dst->regnum);
    } // for
} // srcarg_matrix_replicate

static void state_M4X4(Context *ctx)
{
    const DestArgInfo *info = &ctx->dest_arg;
    if (!writemask_xyzw(info->writemask))
        fail(ctx, "M4X4 writemask must be full");

// !!! FIXME: MSDN:
//The xyzw (default) mask is required for the destination register. Negate and swizzle modifiers are allowed for src0, but not for src1.
//Swizzle and negate modifiers are invalid for the src0 register. The dest and src0 registers cannot be the same.

    srcarg_matrix_replicate(ctx, 1, 4);
} // state_M4X4

static void state_M4X3(Context *ctx)
{
    const DestArgInfo *info = &ctx->dest_arg;
    if (!writemask_xyz(info->writemask))
        fail(ctx, "M4X3 writemask must be .xyz");

// !!! FIXME: MSDN stuff

    srcarg_matrix_replicate(ctx, 1, 3);
} // state_M4X3

static void state_M3X4(Context *ctx)
{
    const DestArgInfo *info = &ctx->dest_arg;
    if (!writemask_xyzw(info->writemask))
        fail(ctx, "M3X4 writemask must be .xyzw");

// !!! FIXME: MSDN stuff

    srcarg_matrix_replicate(ctx, 1, 4);
} // state_M3X4

static void state_M3X3(Context *ctx)
{
    const DestArgInfo *info = &ctx->dest_arg;
    if (!writemask_xyz(info->writemask))
        fail(ctx, "M3X3 writemask must be .xyz");

// !!! FIXME: MSDN stuff

    srcarg_matrix_replicate(ctx, 1, 3);
} // state_M3X3

static void state_M3X2(Context *ctx)
{
    const DestArgInfo *info = &ctx->dest_arg;
    if (!writemask_xy(info->writemask))
        fail(ctx, "M3X2 writemask must be .xy");

// !!! FIXME: MSDN stuff

    srcarg_matrix_replicate(ctx, 1, 2);
} // state_M3X2

static void state_RET(Context *ctx)
{
    // MSDN all but says that assembly shaders are more or less serialized
    //  HLSL functions, and a RET means you're at the end of one, unlike how
    //  most CPUs would behave. This is actually really helpful,
    //  since we can use high-level constructs and not a mess of GOTOs,
    //  which is a godsend for GLSL...this also means we can consider things
    //  like a LOOP without a matching ENDLOOP within a label's section as
    //  an error.
    if (ctx->loops > 0)
        fail(ctx, "LOOP without ENDLOOP");
    if (ctx->reps > 0)
        fail(ctx, "REP without ENDREP");
} // state_RET

static int check_label_register(Context *ctx, int arg, const char *opcode)
{
    const SourceArgInfo *info = &ctx->source_args[arg];
    const RegisterType regtype = info->regtype;
    const int regnum = info->regnum;

    if (regtype != REG_TYPE_LABEL)
        return failf(ctx, "%s with a non-label register specified", opcode);

    else if (!shader_version_atleast(ctx, 2, 0))
        return failf(ctx, "%s not supported in Shader Model 1", opcode);

    else if ((shader_version_atleast(ctx, 2, 255)) && (regnum > 2047))
        return failf(ctx, "label register number must be <= 2047");

    else if (regnum > 15)
        return failf(ctx, "label register number must be <= 15");

    return 0;
} // check_label_register

static void state_LABEL(Context *ctx)
{
    if (ctx->previous_opcode != OPCODE_RET)
        fail(ctx, "LABEL not followed by a RET");
    check_label_register(ctx, 0, "LABEL");
    set_defined_register(ctx, REG_TYPE_LABEL, ctx->source_args[0].regnum);
} // state_LABEL

static void check_call_loop_wrappage(Context *ctx, const int regnum)
{
    // msdn says subroutines inherit aL register if you're in a loop when
    //  you call, and further more _if you ever call this function in a loop,
    //  it must always be called in a loop_. So we'll just pass our loop
    //  variable as a function parameter in those cases.

    const int current_usage = (ctx->loops > 0) ? 1 : -1;
    RegisterList *reg = reglist_find(&ctx->used_registers, REG_TYPE_LABEL, regnum);
    assert(reg != NULL);

    if (reg->misc == 0)
        reg->misc = current_usage;
    else if (reg->misc != current_usage)
    {
        if (current_usage == 1)
            fail(ctx, "CALL to this label must be wrapped in LOOP/ENDLOOP");
        else
            fail(ctx, "CALL to this label must not be wrapped in LOOP/ENDLOOP");
    } // else if
} // check_call_loop_wrappage

static void state_CALL(Context *ctx)
{
    if (check_label_register(ctx, 0, "CALL") != FAIL)
        check_call_loop_wrappage(ctx, ctx->source_args[0].regnum);
} // state_CALL

static void state_CALLNZ(Context *ctx)
{
    const RegisterType regtype = ctx->source_args[1].regtype;
    if ((regtype != REG_TYPE_CONSTBOOL) && (regtype != REG_TYPE_PREDICATE))
        fail(ctx, "CALLNZ argument isn't constbool or predicate register");
    else if (check_label_register(ctx, 0, "CALLNZ") != FAIL)
        check_call_loop_wrappage(ctx, ctx->source_args[0].regnum);
} // state_CALLNZ

static void state_MOVA(Context *ctx)
{
    if (ctx->dest_arg.regtype != REG_TYPE_ADDRESS)
        fail(ctx, "MOVA argument isn't address register");
} // state_MOVA

static void state_RCP(Context *ctx)
{
    if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "RCP without replicate swizzzle");
} // state_RCP

static void state_LOOP(Context *ctx)
{
    if (ctx->source_args[0].regtype != REG_TYPE_LOOP)
        fail(ctx, "LOOP argument isn't loop register");
    else if (ctx->source_args[1].regtype != REG_TYPE_CONSTINT)
        fail(ctx, "LOOP argument isn't constint register");
    else
        ctx->loops++;
} // state_LOOP

static void state_ENDLOOP(Context *ctx)
{
    // !!! FIXME: check that we aren't straddling an IF block.
    if (ctx->loops <= 0)
        fail(ctx, "ENDLOOP without LOOP");
    ctx->loops--;
} // state_ENDLOOP

static void state_BREAKP(Context *ctx)
{
    const RegisterType regtype = ctx->source_args[0].regtype;
    if (regtype != REG_TYPE_PREDICATE)
        fail(ctx, "BREAKP argument isn't predicate register");
    else if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "BREAKP without replicate swizzzle");
    else if ((ctx->loops == 0) && (ctx->reps == 0))
        fail(ctx, "BREAKP outside LOOP/ENDLOOP or REP/ENDREP");
} // state_BREAKP

static void state_BREAK(Context *ctx)
{
    if ((ctx->loops == 0) && (ctx->reps == 0))
        fail(ctx, "BREAK outside LOOP/ENDLOOP or REP/ENDREP");
} // state_BREAK

static void state_SETP(Context *ctx)
{
    const RegisterType regtype = ctx->dest_arg.regtype;
    if (regtype != REG_TYPE_PREDICATE)
        fail(ctx, "SETP argument isn't predicate register");
} // state_SETP

static void state_REP(Context *ctx)
{
    const RegisterType regtype = ctx->source_args[0].regtype;
    if (regtype != REG_TYPE_CONSTINT)
        fail(ctx, "REP argument isn't constint register");

    ctx->reps++;
    if (ctx->reps > ctx->max_reps)
        ctx->max_reps = ctx->reps;
} // state_REP

static void state_ENDREP(Context *ctx)
{
    // !!! FIXME: check that we aren't straddling an IF block.
    if (ctx->reps <= 0)
        fail(ctx, "ENDREP without REP");
    ctx->reps--;
} // state_ENDREP

static void state_CMP(Context *ctx)
{
    ctx->cmps++;

    // extra limitations for ps <= 1.4 ...
    if (!shader_version_atleast(ctx, 1, 4))
    {
        int i;
        const DestArgInfo *dst = &ctx->dest_arg;
        const RegisterType dregtype = dst->regtype;
        const int dregnum = dst->regnum;

        if (ctx->cmps > 3)
            fail(ctx, "only 3 CMP instructions allowed in this shader model");

        for (i = 0; i < 3; i++)
        {
            const SourceArgInfo *src = &ctx->source_args[i];
            const RegisterType sregtype = src->regtype;
            const int sregnum = src->regnum;
            if ((dregtype == sregtype) && (dregnum == sregnum))
                fail(ctx, "CMP dest can't match sources in this shader model");
        } // for

        ctx->instruction_count++;  // takes an extra slot in ps_1_2 and _3.
    } // if
} // state_CMP

static void state_DP4(Context *ctx)
{
    // extra limitations for ps <= 1.4 ...
    if (!shader_version_atleast(ctx, 1, 4))
        ctx->instruction_count++;  // takes an extra slot in ps_1_2 and _3.
} // state_DP4

static void state_CND(Context *ctx)
{
    // apparently it was removed...it's not in the docs past ps_1_4 ...
    if (shader_version_atleast(ctx, 2, 0))
        fail(ctx, "CND not allowed in this shader model");

    // extra limitations for ps <= 1.4 ...
    else if (!shader_version_atleast(ctx, 1, 4))
    {
        const SourceArgInfo *src = &ctx->source_args[0];
        if ((src->regtype != REG_TYPE_TEMP) || (src->regnum != 0) ||
            (src->swizzle != 0x0000))
        {
            fail(ctx, "CND src must be r0.a in this shader model");
        } // if
    } // if
} // state_CND

static void state_POW(Context *ctx)
{
    if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "POW src0 must have replicate swizzle");
    else if (!replicate_swizzle(ctx->source_args[1].swizzle))
        fail(ctx, "POW src1 must have replicate swizzle");
} // state_POW

static void state_LOG(Context *ctx)
{
    if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "LOG src0 must have replicate swizzle");
} // state_LOG

static void state_LOGP(Context *ctx)
{
    if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "LOGP src0 must have replicate swizzle");
} // state_LOGP

static void state_SINCOS(Context *ctx)
{
    const DestArgInfo *dst = &ctx->dest_arg;
    const int mask = dst->writemask;
    if (!writemask_x(mask) && !writemask_y(mask) && !writemask_xy(mask))
        fail(ctx, "SINCOS write mask must be .x or .y or .xy");

    else if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "SINCOS src0 must have replicate swizzle");

    else if (dst->result_mod & MOD_SATURATE)  // according to msdn...
        fail(ctx, "SINCOS destination can't use saturate modifier");

    // this opcode needs extra registers, with extra limitations, for <= sm2.
    else if (!shader_version_atleast(ctx, 3, 0))
    {
        int i;
        for (i = 1; i < 3; i++)
        {
            if (ctx->source_args[i].regtype != REG_TYPE_CONST)
            {
                failf(ctx, "SINCOS src%d must be constfloat", i);
                return;
            } // if
        } // for

        if (ctx->source_args[1].regnum == ctx->source_args[2].regnum)
            fail(ctx, "SINCOS src1 and src2 must be different registers");
    } // if
} // state_SINCOS

static void state_IF(Context *ctx)
{
    if (ctx->source_args[0].regtype != REG_TYPE_CONSTBOOL)
        fail(ctx, "IF src0 must be CONSTBOOL");
    // !!! FIXME: track if nesting depth.
} // state_IF

static void state_IFC(Context *ctx)
{
    if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "IFC src0 must have replicate swizzle");
    else if (!replicate_swizzle(ctx->source_args[1].swizzle))
        fail(ctx, "IFC src1 must have replicate swizzle");
    // !!! FIXME: track if nesting depth.
} // state_IFC

static void state_BREAKC(Context *ctx)
{
    if (!replicate_swizzle(ctx->source_args[0].swizzle))
        fail(ctx, "BREAKC src1 must have replicate swizzle");
    else if (!replicate_swizzle(ctx->source_args[1].swizzle))
        fail(ctx, "BREAKC src2 must have replicate swizzle");
    else if ((ctx->loops == 0) && (ctx->reps == 0))
        fail(ctx, "BREAKC outside LOOP/ENDLOOP or REP/ENDREP");
} // state_BREAKC

static void state_TEXKILL(Context *ctx)
{
    // The MSDN docs say this should be a source arg, but the driver docs
    //  say it's a dest arg. That's annoying.
    const DestArgInfo *info = &ctx->dest_arg;
    const RegisterType regtype = info->regtype;
    if (!writemask_xyzw(info->writemask))
        fail(ctx, "TEXKILL writemask must be .xyzw");
    else if ((regtype != REG_TYPE_TEMP) && (regtype != REG_TYPE_TEXTURE))
        fail(ctx, "TEXKILL must use a temp or texture register");

    // !!! FIXME: "If a temporary register is used, all components must have been previously written."
    // !!! FIXME: "If a texture register is used, all components that are read must have been declared."
    // !!! FIXME: there are further limitations in ps_1_3 and earlier.
} // state_TEXKILL

static void state_TEXLD(Context *ctx)
{
    if (shader_version_atleast(ctx, 2, 0))
    {
        const SourceArgInfo *src0 = &ctx->source_args[0];
        const SourceArgInfo *src1 = &ctx->source_args[1];

        //const RegisterType rt0 = src0->regtype;

        // !!! FIXME: msdn says it has to be temp, but Microsoft's HLSL
        // !!! FIXME:  compiler is generating code that uses oC0 for a dest.
        //if (ctx->dest_arg.regtype != REG_TYPE_TEMP)
        //    fail(ctx, "TEXLD dest must be a temp register");

        // !!! FIXME: this can be an REG_TYPE_INPUT, DCL'd to TEXCOORD.
        //else if ((rt0 != REG_TYPE_TEXTURE) && (rt0 != REG_TYPE_TEMP))
        //    fail(ctx, "TEXLD src0 must be texture or temp register");
        //else

        if (src0->src_mod != SRCMOD_NONE)
            fail(ctx, "TEXLD src0 must have no modifiers");
        else if (src1->regtype != REG_TYPE_SAMPLER)
            fail(ctx, "TEXLD src1 must be sampler register");
        else if (src1->src_mod != SRCMOD_NONE)
            fail(ctx, "TEXLD src0 must have no modifiers");

        // Shader Model 3 added swizzle support to this opcode.
        if (!shader_version_atleast(ctx, 3, 0))
        {
            if (!no_swizzle(src0->swizzle))
                fail(ctx, "TEXLD src0 must not swizzle");
            else if (!no_swizzle(src1->swizzle))
                fail(ctx, "TEXLD src1 must not swizzle");
        } // if

        if ( ((TextureType) ctx->source_args[1].regnum) == TEXTURE_TYPE_CUBE )
            ctx->instruction_count += 3;
    } // if

    // !!! FIXME: checks for ps_1_4 and ps_1_0 versions here...
} // state_TEXLD

static void state_TEXLDL(Context *ctx)
{
    if (!shader_version_atleast(ctx, 3, 0))
        fail(ctx, "TEXLDL in version < Shader Model 3.0");
    else if (ctx->source_args[1].regtype != REG_TYPE_SAMPLER)
        fail(ctx, "TEXLDL src1 must be sampler register");
    else
    {
        if ( ((TextureType) ctx->source_args[1].regnum) == TEXTURE_TYPE_CUBE )
            ctx->instruction_count += 3;
    } // else
} // state_TEXLDL

static void state_DP2ADD(Context *ctx)
{
    if (!replicate_swizzle(ctx->source_args[2].swizzle))
        fail(ctx, "IFC src2 must have replicate swizzle");
} // state_DP2ADD


// Lookup table for instruction opcodes...
typedef struct
{
    const char *opcode_string;
    int slots;  // number of instruction slots this opcode eats.
    MOJOSHADER_shaderType shader_types;  // mask of types that can use opcode.
    args_function parse_args;
    state_function state;
    emit_function emitter[STATICARRAYLEN(profiles)];
} Instruction;

// These have to be in the right order! This array is indexed by the value
//  of the instruction token.
static const Instruction instructions[] =
{
    // INSTRUCTION_STATE means this opcode has to update the state machine
    //  (we're entering an ELSE block, etc). INSTRUCTION means there's no
    //  state, just go straight to the emitters.
    #define INSTRUCTION_STATE(op, slots, argsseq, t) { \
        #op, slots, t, parse_args_##argsseq, state_##op, PROFILE_EMITTERS(op) \
    }
    #define INSTRUCTION(op, slots, argsseq, t) { \
        #op, slots, t, parse_args_##argsseq, 0, PROFILE_EMITTERS(op) \
    }

    // !!! FIXME: Some of these MOJOSHADER_TYPE_ANYs need to have their scope
    // !!! FIXME:  reduced to just PIXEL or VERTEX.

    INSTRUCTION(NOP, 1, NULL, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(MOV, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(ADD, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(SUB, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(MAD, 1, DSSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(MUL, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(RCP, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(RSQ, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(DP3, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(DP4, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(MIN, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(MAX, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(SLT, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(SGE, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(EXP, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(LOG, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(LIT, 3, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(DST, 1, DSS, MOJOSHADER_TYPE_VERTEX),
    INSTRUCTION(LRP, 2, DSSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(FRC, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(M4X4, 4, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(M4X3, 3, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(M3X4, 4, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(M3X3, 3, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(M3X2, 2, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(CALL, 2, S, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(CALLNZ, 3, SS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(LOOP, 3, SS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(RET, 1, NULL, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(ENDLOOP, 2, NULL, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(LABEL, 0, S, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(DCL, 0, DCL, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(POW, 3, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(CRS, 2, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(SGN, 3, DSSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(ABS, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(NRM, 3, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(SINCOS, 8, SINCOS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(REP, 3, S, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(ENDREP, 2, NULL, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(IF, 3, S, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(IFC, 3, SS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(ELSE, 1, NULL, MOJOSHADER_TYPE_ANY),  // !!! FIXME: state!
    INSTRUCTION(ENDIF, 1, NULL, MOJOSHADER_TYPE_ANY), // !!! FIXME: state!
    INSTRUCTION_STATE(BREAK, 1, NULL, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(BREAKC, 3, SS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(MOVA, 1, DS, MOJOSHADER_TYPE_VERTEX),
    INSTRUCTION_STATE(DEFB, 0, DEFB, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(DEFI, 0, DEF, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION_STATE(TEXCRD, 1, TEXCRD, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION_STATE(TEXKILL, 2, D, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION_STATE(TEXLD, 1, TEXLD, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXBEM, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXBEML, 2, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXREG2AR, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXREG2GB, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXM3X2PAD, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXM3X2TEX, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXM3X3PAD, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXM3X3TEX, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(RESERVED, 0, NULL, MOJOSHADER_TYPE_UNKNOWN),
    INSTRUCTION(TEXM3X3SPEC, 1, DSS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXM3X3VSPEC, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(EXPP, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(LOGP, 1, DS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(CND, 1, DSSS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION_STATE(DEF, 0, DEF, MOJOSHADER_TYPE_ANY),
    INSTRUCTION(TEXREG2RGB, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXDP3TEX, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXM3X2DEPTH, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXDP3, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXM3X3, 1, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXDEPTH, 1, D, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION_STATE(CMP, 1, DSSS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(BEM, 2, DSS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION_STATE(DP2ADD, 2, DSSS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(DSX, 2, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(DSY, 2, DS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION(TEXLDD, 3, DSSSS, MOJOSHADER_TYPE_PIXEL),
    INSTRUCTION_STATE(SETP, 1, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(TEXLDL, 2, DSS, MOJOSHADER_TYPE_ANY),
    INSTRUCTION_STATE(BREAKP, 3, S, MOJOSHADER_TYPE_ANY),

    // !!! FIXME: TEXLDB?

    #undef INSTRUCTION
    #undef INSTRUCTION_STATE
};


// parse various token types...

static int parse_instruction_token(Context *ctx)
{
    int retval = NOFAIL;
    const uint32 *start_tokens = ctx->tokens;
    const uint32 start_tokencount = ctx->tokencount;
    const uint32 token = SWAP32(*(ctx->tokens));
    const uint32 opcode = (token & 0xFFFF);
    const uint32 controls = ((token >> 16) & 0xFF);
    const uint32 insttoks = ((token >> 24) & 0x0F);
    const int coissue = (token & 0x40000000) ? 1 : 0;
    const int predicated = (token & 0x10000000) ? 1 : 0;

    if ( opcode >= (sizeof (instructions) / sizeof (instructions[0])) )
        return 0;  // not an instruction token, or just not handled here.

    const Instruction *instruction = &instructions[opcode];
    const emit_function emitter = instruction->emitter[ctx->profileid];

    if ((token & 0x80000000) != 0)
        return fail(ctx, "instruction token high bit must be zero.");  // so says msdn.

    if (coissue)
    {
        if (!shader_is_pixel(ctx))
            return fail(ctx, "coissue instruction on non-pixel shader");
        else if (shader_version_atleast(ctx, 2, 0))
            return fail(ctx, "coissue instruction in Shader Model >= 2.0");
        // !!! FIXME: I'm not sure what this actually means, yet.
        return fail(ctx, "coissue instructions unsupported");
    } // if

    if ((ctx->shader_type & instruction->shader_types) == 0)
    {
        return failf(ctx, "opcode '%s' not available in this shader type.",
                     instruction->opcode_string);
    } // if

    memset(ctx->dwords, '\0', sizeof (ctx->dwords));
    ctx->instruction_controls = controls;
    ctx->predicated = predicated;

    // Update the context with instruction's arguments.
    ctx->tokens++;
    ctx->tokencount--;
    retval = instruction->parse_args(ctx);
    assert((isfail(ctx)) || (retval >= 0));

    if ( (!isfail(ctx)) && (predicated) )
    {
        if (parse_predicated_token(ctx) != FAIL)
            retval++;  // one more token.
    } // if

    // parse_args() moves these forward for convenience...reset them.
    ctx->tokens = start_tokens;
    ctx->tokencount = start_tokencount;

    if (!isfail(ctx))
    {
        if (instruction->state != NULL)
            instruction->state(ctx);
    } // if

    ctx->instruction_count += instruction->slots;

    if (isfail(ctx))
        retval = FAIL;
    else
        emitter(ctx);  // call the profile's emitter.

    ctx->previous_opcode = opcode;
    ctx->scratch_registers = 0;  // reset after every instruction.

    if (!isfail(ctx))
    {
        if (!shader_version_atleast(ctx, 2, 0))
        {
            if (insttoks != 0)  // reserved field in shaders < 2.0 ...
                return fail(ctx, "instruction token count must be zero");
        } // if
        else
        {
            if (retval != (insttoks+1))
            {
                return failf(ctx,
                        "wrong token count (%u, not %u) for opcode '%s'.",
                        (uint) retval, (uint) (insttoks+1),
                        instruction->opcode_string);
            } // if
        } // else
    } // if

    return retval;
} // parse_instruction_token


static int parse_version_token(Context *ctx, const char *profilestr)
{
    if (isfail(ctx))  // catch preexisting errors here.
        return FAIL;

    if (ctx->tokencount == 0)
        return fail(ctx, "Expected version token, got none at all.");

    const uint32 token = SWAP32(*(ctx->tokens));
    const uint32 shadertype = ((token >> 16) & 0xFFFF);
    const uint8 major = (uint8) ((token >> 8) & 0xFF);
    const uint8 minor = (uint8) (token & 0xFF);

    ctx->version_token = token;

    // 0xFFFF == pixel shader, 0xFFFE == vertex shader
    if (shadertype == 0xFFFF)
    {
        ctx->shader_type = MOJOSHADER_TYPE_PIXEL;
        ctx->shader_type_str = "ps";
    } // if
    else if (shadertype == 0xFFFE)
    {
        ctx->shader_type = MOJOSHADER_TYPE_VERTEX;
        ctx->shader_type_str = "vs";
    } // else if
    else  // geometry shader? Bogus data?
    {
        return fail(ctx, "Unsupported shader type or not a shader at all");
    } // else

    ctx->major_ver = major;
    ctx->minor_ver = minor;

    if (!shader_version_supported(major, minor))
    {
        return failf(ctx, "Shader Model %u.%u is currently unsupported.",
                     (uint) major, (uint) minor);
    } // if

    ctx->profile->start_emitter(ctx, profilestr);
    return 1;  // ate one token.
} // parse_version_token


// Microsoft's tools add a CTAB comment to all shaders. This is the
//  "constant table," or specifically: D3DXSHADER_CONSTANTTABLE:
//  http://msdn.microsoft.com/en-us/library/bb205440(VS.85).aspx
// This may tell us high-level truths about an otherwise generic low-level
//  registers, for instance, how large an array actually is, etc.
static void parse_constant_table(Context *ctx, const uint32 bytes)
{
    const uint8 *start = (uint8 *) &ctx->tokens[2];
    const uint32 id = SWAP32(ctx->tokens[1]);
    const uint32 size = SWAP32(ctx->tokens[2]);
    const uint32 creator = SWAP32(ctx->tokens[3]);
    const uint32 version = SWAP32(ctx->tokens[4]);
    const uint32 constants = SWAP32(ctx->tokens[5]);
    const uint32 constantinfo = SWAP32(ctx->tokens[6]);
    const uint32 target = SWAP32(ctx->tokens[8]);
    uint32 i = 0;

    if (id != 0x42415443)  // 0x42415443 == 'CTAB'
        return;  // not the constant table.

    if (size != 28)
        return;  // only handle this version of the struct.

    if (version != ctx->version_token) goto corrupt_ctab;
    if (creator >= bytes) goto corrupt_ctab;
    if ((constantinfo + (constants * 20)) >= bytes) goto corrupt_ctab;
    if (target >= bytes) goto corrupt_ctab;

    ctx->have_ctab = 1;

    for (i = 0; i < constants; i++)
    {
        // we only care about deciding which variables might be arrays at
        //  the moment, but there's lots of other good info in the CTAB.
        const uint8 *ptr = start + constantinfo + (i * 20);
        const uint32 name = SWAP32(*((uint32 *) (ptr + 0)));
        const uint16 regset = SWAP16(*((uint16 *) (ptr + 4)));
        const uint16 regidx = SWAP16(*((uint16 *) (ptr + 6)));
        const uint16 regcnt = SWAP16(*((uint16 *) (ptr + 8)));
        const uint32 typeinf = SWAP32(*((uint32 *) (ptr + 12)));
        const uint32 defval = SWAP32(*((uint32 *) (ptr + 16)));
        MOJOSHADER_uniformType mojotype = MOJOSHADER_UNIFORM_UNKNOWN;

        if (name >= bytes) goto corrupt_ctab;
        if ((typeinf + 16) >= bytes) goto corrupt_ctab;
        if (defval >= bytes) goto corrupt_ctab;

        switch (regset)
        {
            case 0: mojotype = MOJOSHADER_UNIFORM_BOOL; break;
            case 1: mojotype = MOJOSHADER_UNIFORM_INT; break;
            case 2: mojotype = MOJOSHADER_UNIFORM_FLOAT; break;
            case 3: /* SAMPLER */ break;
            default: goto corrupt_ctab;
        } // switch

        if (mojotype != MOJOSHADER_UNIFORM_UNKNOWN)
        {
            VariableList *item;
            item = (VariableList *) Malloc(ctx, sizeof (VariableList));
            if (item != NULL)
            {
                item->type = mojotype;
                item->index = regidx;
                item->count = regcnt;
                item->constant = NULL;
                item->used = 0;
                item->next = ctx->variables;
                ctx->variables = item;
            } // if
        } // if
    } // for

    return;

corrupt_ctab:
    fail(ctx, "Shader has corrupt CTAB data");
} // parse_constant_table


static int parse_comment_token(Context *ctx)
{
    const uint32 token = SWAP32(*(ctx->tokens));
    if ((token & 0xFFFF) != 0xFFFE)
        return 0;  // not a comment token.
    else if ((token & 0x80000000) != 0)
        return fail(ctx, "comment token high bit must be zero.");  // so says msdn.
    else
    {
        const uint32 commenttoks = ((token >> 16) & 0xFFFF);
        if ((commenttoks >= 8) && (commenttoks < ctx->tokencount))
            parse_constant_table(ctx, commenttoks * 4);
        return commenttoks + 1;  // comment data plus the initial token.
    } // else

    // shouldn't hit this.
    return failf(ctx, "Logic error at %s:%d", __FILE__, __LINE__);
} // parse_comment_token


static int parse_end_token(Context *ctx)
{
    if (SWAP32(*(ctx->tokens)) != 0x0000FFFF)   // end token always 0x0000FFFF.
        return 0;  // not us, eat no tokens.

    if (ctx->tokencount != 1)  // we _must_ be last. If not: fail.
        return fail(ctx, "end token before end of stream");

    ctx->profile->end_emitter(ctx);

    return END_OF_STREAM;
} // parse_end_token


static int parse_phase_token(Context *ctx)
{
    if (SWAP32(*(ctx->tokens)) != 0x0000FFFD) // phase token always 0x0000FFFD.
        return 0;  // not us, eat no tokens.
    else if ( (!shader_is_pixel(ctx)) || (!shader_version_exactly(ctx, 1, 4)) )
        return fail(ctx, "phase token only available in 1.4 pixel shaders");
    ctx->profile->phase_emitter(ctx);
    return 1;
} // parse_phase_token


static int parse_token(Context *ctx)
{
    int rc = 0;

    if (isfail(ctx))
        return FAIL;  // just in case...catch previously unhandled fails here.

    if (ctx->output_stack_len != 0)
        return fail(ctx, "BUG: output stack isn't empty on new token!");

    if (ctx->tokencount == 0)
        return fail(ctx, "unexpected end of shader.");

    if ((rc = parse_comment_token(ctx)) != 0)
        return rc;

    if ((rc = parse_end_token(ctx)) != 0)
        return rc;

    if ((rc = parse_phase_token(ctx)) != 0)
        return rc;

    if ((rc = parse_instruction_token(ctx)) != 0)
        return rc;

    return failf(ctx, "unknown token (%u)", (uint) *ctx->tokens);
} // parse_token


// #define this to force app to supply an allocator, so there's no reference
//  to the C runtime's malloc() and free()...
#if MOJOSHADER_FORCE_ALLOCATOR
#define internal_malloc NULL
#define internal_free NULL
#else
static void *internal_malloc(int bytes, void *d) { return malloc(bytes); }
static void internal_free(void *ptr, void *d) { free(ptr); }
#endif

static int find_profile_id(const char *profile)
{
    int i;
    for (i = 0; i < STATICARRAYLEN(profileMap); i++)
    {
        const char *name = profileMap[i].from;
        if (strcmp(name, profile) == 0)
        {
            profile = profileMap[i].to;
            break;
        } // if
    } // for

    for (i = 0; i < STATICARRAYLEN(profiles); i++)
    {
        const char *name = profiles[i].name;
        if (strcmp(name, profile) == 0)
            return i;
    } // for

    return -1;  // no match.
} // find_profile_id


static Context *build_context(const char *profile,
                              const unsigned char *tokenbuf,
                              const unsigned int bufsize,
                              MOJOSHADER_malloc m, MOJOSHADER_free f, void *d)
{
    if (m == NULL) m = internal_malloc;
    if (f == NULL) f = internal_free;

    Context *ctx = (Context *) m(sizeof (Context), d);
    if (ctx == NULL)
        return NULL;

    memset(ctx, '\0', sizeof (Context));
    ctx->malloc = m;
    ctx->free = f;
    ctx->malloc_data = d;
    ctx->tokens = (const uint32 *) tokenbuf;
    ctx->tokencount = bufsize / sizeof (uint32);
    ctx->endline = endline_str;
    ctx->endline_len = strlen(ctx->endline);
    ctx->globals.tail = &ctx->globals.head;
    ctx->helpers.tail = &ctx->helpers.head;
    ctx->subroutines.tail = &ctx->subroutines.head;
    ctx->mainline_intro.tail = &ctx->mainline_intro.head;
    ctx->mainline.tail = &ctx->mainline.head;
    ctx->ignore.tail = &ctx->ignore.head;
    ctx->output = &ctx->mainline;
    ctx->last_address_reg_component = -1;

    const int profileid = find_profile_id(profile);
    ctx->profileid = profileid;
    if (profileid >= 0)
        ctx->profile = &profiles[profileid];
    else
        failf(ctx, "Profile '%s' is unknown or unsupported", profile);

    return ctx;
} // build_context


static void free_output_list(MOJOSHADER_free f, void *d, OutputListNode *item)
{
    while (item != NULL)
    {
        OutputListNode *next = item->next;
        if (item->str != NULL)
            f(item->str, d);
        f(item, d);
        item = next;
    } // while
} // free_output_list


static void free_constants_list(MOJOSHADER_free f, void *d, ConstantsList *item)
{
    while (item != NULL)
    {
        ConstantsList *next = item->next;
        f(item, d);
        item = next;
    } // while
} // free_constants_list


static void free_variable_list(MOJOSHADER_free f, void *d, VariableList *item)
{
    while (item != NULL)
    {
        VariableList *next = item->next;
        f(item, d);
        item = next;
    } // while
} // free_variable_list


static void destroy_context(Context *ctx)
{
    if (ctx != NULL)
    {
        MOJOSHADER_free f = ((ctx->free != NULL) ? ctx->free : internal_free);
        void *d = ctx->malloc_data;
        if (ctx->output_bytes != NULL)
            f(d, ctx->output_bytes);
        free_output_list(f, d, ctx->globals.head.next);
        free_output_list(f, d, ctx->helpers.head.next);
        free_output_list(f, d, ctx->subroutines.head.next);
        free_output_list(f, d, ctx->mainline_intro.head.next);
        free_output_list(f, d, ctx->mainline.head.next);
        free_output_list(f, d, ctx->ignore.head.next);
        free_constants_list(f, d, ctx->constants);
        free_reglist(f, d, ctx->used_registers.next);
        free_reglist(f, d, ctx->defined_registers.next);
        free_reglist(f, d, ctx->uniforms.next);
        free_reglist(f, d, ctx->attributes.next);
        free_reglist(f, d, ctx->samplers.next);
        free_variable_list(f, d, ctx->variables);
        if ((ctx->failstr != NULL) && (ctx->failstr != out_of_mem_str))
            f((void *) ctx->failstr, d);
        f(ctx, d);
    } // if
} // destroy_context


static void append_list(char **_wptr, const char *endline,
                        const size_t endline_len, OutputListNode *item)
{
    char *wptr = *_wptr;
    while (item != NULL)
    {
        const size_t len = strlen(item->str);
        memcpy(wptr, item->str, len);
        wptr += len;
        memcpy(wptr, endline, endline_len);
        wptr += endline_len;
        item = item->next;
    } // while
    *wptr = '\0';
    *_wptr = wptr;
} // append_list


static char *build_output(Context *ctx)
{
    // add a byte for the null terminator if we're doing text output.
    const int plusbytes = (ctx->output_bytes == NULL) ? 1 : 0;
    char *retval = (char *) Malloc(ctx, ctx->output_len + plusbytes);
    if (retval != NULL)
    {
        const char *endl = ctx->endline;
        const size_t endllen = ctx->endline_len;
        char *wptr = retval;
        if (ctx->output_bytes != NULL)
            memcpy(retval, ctx->output_bytes, ctx->output_len);
        else
        {
            append_list(&wptr, endl, endllen, ctx->globals.head.next);
            append_list(&wptr, endl, endllen, ctx->helpers.head.next);
            append_list(&wptr, endl, endllen, ctx->subroutines.head.next);
            append_list(&wptr, endl, endllen, ctx->mainline_intro.head.next);
            append_list(&wptr, endl, endllen, ctx->mainline.head.next);
            // don't append ctx->ignore ... that's why it's called "ignore"
        } // else
    } // if

    return retval;
} // build_output


static char *alloc_varname(Context *ctx, const RegisterList *reg)
{
    const char *varname = ctx->profile->get_varname(ctx, reg->regtype,
                                                    reg->regnum);
    const size_t len = strlen(varname) + 1;
    char *retval = (char *) Malloc(ctx, len);
    if (retval != NULL)
        strcpy(retval, varname);
    return retval;
} // alloc_varname


static MOJOSHADER_uniform *build_uniforms(Context *ctx)
{
    const size_t len = sizeof (MOJOSHADER_uniform) * ctx->uniform_count;
    MOJOSHADER_uniform *retval = (MOJOSHADER_uniform *) Malloc(ctx, len);

    if (retval != NULL)
    {
        MOJOSHADER_uniform *wptr = retval;
        memset(wptr, '\0', len);

        VariableList *var;
        int written = 0;
        for (var = ctx->variables; var != NULL; var = var->next)
        {
            if ((!var->constant) && (var->used))
            {
                const char *name = ctx->profile->get_const_array_varname(ctx,
                                                      var->index, var->count);
                char *namecpy = (char *) Malloc(ctx, strlen(name) + 1);
                if (namecpy != NULL)
                {
                    strcpy(namecpy, name);
                    wptr->type = MOJOSHADER_UNIFORM_FLOAT;
                    wptr->index = var->index;
                    wptr->array_count = var->count;
                    wptr->name = namecpy;
                    wptr++;
                    written++;
                } // if
            } // if
        } // for

        RegisterList *item = ctx->uniforms.next;
        MOJOSHADER_uniformType type = MOJOSHADER_UNIFORM_FLOAT;
        while (written < ctx->uniform_count)
        {
            int skip = 0;

            if (item == NULL)
            {
                fail(ctx, "BUG: mismatched uniform list and count");
                break;
            } // if

            int index = item->regnum;
            switch (item->regtype)
            {
                case REG_TYPE_CONST:
                    skip = (item->array != NULL);
                    type = MOJOSHADER_UNIFORM_FLOAT;
                    break;

                case REG_TYPE_CONSTINT:
                    type = MOJOSHADER_UNIFORM_INT;
                    break;

                case REG_TYPE_CONSTBOOL:
                    type = MOJOSHADER_UNIFORM_BOOL;
                    break;

                default:
                    fail(ctx, "unknown uniform datatype");
                    break;
            } // switch

            if (!skip)
            {
                wptr->type = type;
                wptr->index = index;
                wptr->array_count = 0;
                wptr->name = alloc_varname(ctx, item);
                wptr++;
                written++;
            } // if

            item = item->next;
        } // for
    } // if

    return retval;
} // build_uniforms


static MOJOSHADER_constant *build_constants(Context *ctx)
{
    const size_t len = sizeof (MOJOSHADER_constant) * ctx->constant_count;
    MOJOSHADER_constant *retval = (MOJOSHADER_constant *) Malloc(ctx, len);

    if (retval != NULL)
    {
        ConstantsList *item = ctx->constants;
        int i;

        for (i = 0; i < ctx->constant_count; i++)
        {
            if (item == NULL)
            {
                fail(ctx, "BUG: mismatched constant list and count");
                break;
            } // if

            memcpy(&retval[i], &item->constant, sizeof (MOJOSHADER_constant));
            item = item->next;
        } // for
    } // if

    return retval;
} // build_constants


static MOJOSHADER_sampler *build_samplers(Context *ctx)
{
    const size_t len = sizeof (MOJOSHADER_sampler) * ctx->sampler_count;
    MOJOSHADER_sampler *retval = (MOJOSHADER_sampler *) Malloc(ctx, len);

    if (retval != NULL)
    {
        RegisterList *item = ctx->samplers.next;
        MOJOSHADER_samplerType type = MOJOSHADER_SAMPLER_2D;
        int i;

        memset(retval, '\0', len);

        for (i = 0; i < ctx->sampler_count; i++)
        {
            if (item == NULL)
            {
                fail(ctx, "BUG: mismatched sampler list and count");
                break;
            } // if

            assert(item->regtype == REG_TYPE_SAMPLER);
            switch ((const TextureType) item->index)
            {
                case TEXTURE_TYPE_2D:
                    type = MOJOSHADER_SAMPLER_2D;
                    break;

                case TEXTURE_TYPE_CUBE:
                    type = MOJOSHADER_SAMPLER_CUBE;
                    break;

                case TEXTURE_TYPE_VOLUME:
                    type = MOJOSHADER_SAMPLER_VOLUME;
                    break;

                default:
                    fail(ctx, "Unknown sampler type");
                    break;
            } // switch

            retval[i].type = type;
            retval[i].index = item->regnum;
            retval[i].name = alloc_varname(ctx, item);
            item = item->next;
        } // for
    } // if

    return retval;
} // build_samplers


static MOJOSHADER_attribute *build_attributes(Context *ctx, int *_count)
{
    int count = 0;

    if (ctx->attribute_count == 0)
    {
        *_count = 0;
        return NULL;  // nothing to do.
    } // if

    const size_t len = sizeof (MOJOSHADER_attribute) * ctx->attribute_count;
    MOJOSHADER_attribute *retval = (MOJOSHADER_attribute *) Malloc(ctx, len);

    if (retval != NULL)
    {
        RegisterList *item = ctx->attributes.next;
        MOJOSHADER_attribute *wptr = retval;
        int ignore = 0;
        int i;

        memset(retval, '\0', len);

        for (i = 0; i < ctx->attribute_count; i++)
        {
            if (item == NULL)
            {
                fail(ctx, "BUG: mismatched attribute list and count");
                break;
            } // if

            switch (item->regtype)
            {
                case REG_TYPE_RASTOUT:
                case REG_TYPE_ATTROUT:
                case REG_TYPE_TEXCRDOUT:
                case REG_TYPE_COLOROUT:
                case REG_TYPE_DEPTHOUT:
                    ignore = 1;
                    break;
                case REG_TYPE_TEXTURE:
                case REG_TYPE_MISCTYPE:
                case REG_TYPE_INPUT:
                    ignore = shader_is_pixel(ctx);
                    break;
                default:
                    ignore = 0;
                    break;
            } // switch

            if (!ignore)
            {
                if (shader_is_pixel(ctx))
                    fail(ctx, "BUG: pixel shader with vertex attributes");
                else
                {
                    wptr->usage = item->usage;
                    wptr->index = item->index;
                    wptr->name = alloc_varname(ctx, item);
                    wptr++;
                    count++;
                } // else
            } // if

            item = item->next;
        } // for
    } // if

    *_count = count;
    return retval;
} // build_attributes


static MOJOSHADER_parseData *build_parsedata(Context *ctx)
{
    char *output = NULL;
    MOJOSHADER_constant *constants = NULL;
    MOJOSHADER_uniform *uniforms = NULL;
    MOJOSHADER_attribute *attributes = NULL;
    MOJOSHADER_sampler *samplers = NULL;
    MOJOSHADER_parseData *retval = NULL;
    int attribute_count = 0;

    retval = (MOJOSHADER_parseData*) Malloc(ctx, sizeof(MOJOSHADER_parseData));
    if (retval == NULL)
        return &out_of_mem_data;

    memset(retval, '\0', sizeof (MOJOSHADER_parseData));

    if (!isfail(ctx))
        output = build_output(ctx);

    if (!isfail(ctx))
        constants = build_constants(ctx);

    if (!isfail(ctx))
        uniforms = build_uniforms(ctx);

    if (!isfail(ctx))
        attributes = build_attributes(ctx, &attribute_count);

    if (!isfail(ctx))
        samplers = build_samplers(ctx);

    // check again, in case build_output ran out of memory.
    if (isfail(ctx))
    {
        int i;

        Free(ctx, output);
        Free(ctx, constants);

        if (uniforms != NULL)
        {
            for (i = 0; i < ctx->uniform_count; i++)
                Free(ctx, (void *) uniforms[i].name);
            Free(ctx, uniforms);
        } // if

        if (attributes != NULL)
        {
            for (i = 0; i < attribute_count; i++)
                Free(ctx, (void *) attributes[i].name);
            Free(ctx, attributes);
        } // if

        if (samplers != NULL)
        {
            for (i = 0; i < ctx->sampler_count; i++)
                Free(ctx, (void *) samplers[i].name);
            Free(ctx, samplers);
        } // if

        retval->error = ctx->failstr;  // we recycle.  :)
        ctx->failstr = NULL;  // don't let this get free()'d too soon.
    } // if
    else
    {
        retval->profile = ctx->profile->name;
        retval->output = output;
        retval->output_len = ctx->output_len;
        retval->instruction_count = ctx->instruction_count;
        retval->shader_type = ctx->shader_type;
        retval->major_ver = (int) ctx->major_ver;
        retval->minor_ver = (int) ctx->minor_ver;
        retval->uniform_count = ctx->uniform_count;
        retval->uniforms = uniforms;
        retval->constant_count = ctx->constant_count;
        retval->constants = constants;
        retval->attribute_count = attribute_count;
        retval->attributes = attributes;
        retval->sampler_count = ctx->sampler_count;
        retval->samplers = samplers;
    } // else

    retval->malloc = (ctx->malloc == internal_malloc) ? NULL : ctx->malloc;
    retval->free = (ctx->free == internal_free) ? NULL : ctx->free;
    retval->malloc_data = ctx->malloc_data;

    return retval;
} // build_parsedata


static void process_definitions(Context *ctx)
{
    // !!! FIXME: apparently, pre ps_3_0, sampler registers don't need to be
    // !!! FIXME:  DCL'd before use (default to 2d?). We aren't checking
    // !!! FIXME:  this at the moment, though.

    RegisterList *uitem = &ctx->uniforms;
    RegisterList *prev = &ctx->used_registers;
    RegisterList *item = prev->next;

    determine_constants_arrays(ctx);  // in case this hasn't been called yet.

    while (item != NULL)
    {
        RegisterList *next = item->next;
        const RegisterType regtype = item->regtype;
        const int regnum = item->regnum;

        if (!get_defined_register(ctx, regtype, regnum))
        {
            // haven't already dealt with this one.
            switch (regtype)
            {
                // !!! FIXME: I'm not entirely sure this is right...
                case REG_TYPE_RASTOUT:
                case REG_TYPE_ATTROUT:
                case REG_TYPE_TEXCRDOUT:
                case REG_TYPE_COLOROUT:
                case REG_TYPE_DEPTHOUT:
                    if (shader_is_vertex(ctx)&&shader_version_atleast(ctx,3,0))
                    {
                        fail(ctx, "vs_3 can't use output registers"
                                  " without declaring them first.");
                        return;
                    } // if

                    // Apparently this is an attribute that wasn't DCL'd.
                    //  Add it to the attribute list; deal with it later.
                    add_attribute_register(ctx, item->regtype, item->regnum,
                                           MOJOSHADER_USAGE_UNKNOWN, 0, 0xF);
                    break;

                case REG_TYPE_ADDRESS:
                case REG_TYPE_PREDICATE:
                case REG_TYPE_TEMP:
                case REG_TYPE_LOOP:
                case REG_TYPE_LABEL:
                    ctx->profile->global_emitter(ctx, regtype, regnum);
                    break;

                case REG_TYPE_CONST:
                case REG_TYPE_CONSTINT:
                case REG_TYPE_CONSTBOOL:
                    // separate uniforms into a different list for now.
                    prev->next = next;
                    item->next = NULL;
                    uitem->next = item;
                    uitem = item;
                    item = prev;
                    break;

                default:
                    fail(ctx, "BUG: we used a register we don't know how to define.");
            } // switch
        } // if

        prev = item;
        item = next;
    } // while

    // okay, now deal with uniform/constant arrays...
    VariableList *var;
    for (var = ctx->variables; var != NULL; var = var->next)
    {
        if (var->used)
        {
            if (var->constant)
            {
                ctx->profile->const_array_emitter(ctx, var->constant,
                                                  var->index, var->count);
            } // if
            else
            {
                ctx->profile->array_emitter(ctx, var->index, var->count);
                ctx->uniform_count++;
            } // else
        } // if
    } // for

    // ...and uniforms...
    for (item = ctx->uniforms.next; item != NULL; item = item->next)
    {
        int arraybase = -1;
        int arraysize = -1;

        // check if this is a register contained in an array...
        if (item->regtype == REG_TYPE_CONST)
        {
            for (var = ctx->variables; var != NULL; var = var->next)
            {
                if (!var->used)
                    continue;

                const int regnum = item->regnum;
                const int lo = var->index;
                if ( (regnum >= lo) && (regnum < (lo + var->count)) )
                {
                    assert(!var->constant);
                    item->array = var;  // used when building parseData.
                    arraybase = lo;
                    arraysize = var->count;
                    break;
                } // if
            } // for
        } // if

        if (arraysize < 0)  // not part of an array?
            ctx->uniform_count++;

        ctx->profile->uniform_emitter(ctx, item->regtype, item->regnum,
                                      arraybase, arraysize);
    } // for

    // ...and samplers...
    for (item = ctx->samplers.next; item != NULL; item = item->next)
    {
        ctx->sampler_count++;
        ctx->profile->sampler_emitter(ctx, item->regnum,
                                      (TextureType) item->index);
    } // for

    // ...and attributes... (find POSITION0 here, so it's always first).
    for (item = ctx->attributes.next; item != NULL; item = item->next)
    {
        if ((item->usage == MOJOSHADER_USAGE_POSITION) && (item->index == 0))
        {
            ctx->attribute_count++;
            ctx->profile->attribute_emitter(ctx, item->regtype, item->regnum,
                                            MOJOSHADER_USAGE_POSITION, 0,
                                            item->writemask);
            break;
        } // if
    } // for

    // ...and attributes... (everything but POSITION0).
    for (item = ctx->attributes.next; item != NULL; item = item->next)
    {
        if ((item->usage != MOJOSHADER_USAGE_POSITION) || (item->index != 0))
        {
            ctx->attribute_count++;
            ctx->profile->attribute_emitter(ctx, item->regtype, item->regnum,
                                            item->usage, item->index,
                                            item->writemask);
        } // if
    } // for
} // process_definitions


// API entry point...

const MOJOSHADER_parseData *MOJOSHADER_parse(const char *profile,
                                             const unsigned char *tokenbuf,
                                             const unsigned int bufsize,
                                             MOJOSHADER_malloc m,
                                             MOJOSHADER_free f, void *d)
{
    MOJOSHADER_parseData *retval = NULL;
    Context *ctx = NULL;
    int rc = FAIL;

    if ( ((m == NULL) && (f != NULL)) || ((m != NULL) && (f == NULL)) )
        return &out_of_mem_data;  // supply both or neither.

    if ((ctx = build_context(profile, tokenbuf, bufsize, m, f, d)) == NULL)
        return &out_of_mem_data;

    // Version token always comes first.
    rc = parse_version_token(ctx, profile);

    // parse out the rest of the tokens after the version token...
    while ( (rc > 0) && (!isfail(ctx)) )
    {
        // reset for every token, and consider an error if it ever overflows!
        ctx->scratchidx = 0;

        if ( ((uint32) rc) > ctx->tokencount )
            fail(ctx, "Corrupted or truncated shader");
        else
        {
            ctx->tokens += rc;
            ctx->tokencount -= rc;
            rc = parse_token(ctx);
        } // else
    } // while

    if (!isfail(ctx))
        process_definitions(ctx);

    if (!isfail(ctx))
        ctx->profile->finalize_emitter(ctx);

    retval = build_parsedata(ctx);
    destroy_context(ctx);
    return retval;
} // MOJOSHADER_parse


void MOJOSHADER_freeParseData(const MOJOSHADER_parseData *_data)
{
    MOJOSHADER_parseData *data = (MOJOSHADER_parseData *) _data;
    if ((data == NULL) || (data == &out_of_mem_data))
        return;  // no-op.

    MOJOSHADER_free f = (data->free == NULL) ? internal_free : data->free;
    void *d = data->malloc_data;
    int i;

    // we don't f(data->profile), because that's internal static data.

    if (data->output != NULL)  // check for NULL in case of dumb free() impl.
        f((void *) data->output, d);

    if (data->constants != NULL)
        f((void *) data->constants, d);

    if (data->uniforms != NULL)
    {
        for (i = 0; i < data->uniform_count; i++)
        {
            if (data->uniforms[i].name != NULL)
                f((void *) data->uniforms[i].name, d);
        } // for
        f((void *) data->uniforms, d);
    } // if

    if (data->attributes != NULL)
    {
        for (i = 0; i < data->attribute_count; i++)
        {
            if (data->attributes[i].name != NULL)
                f((void *) data->attributes[i].name, d);
        } // for
        f((void *) data->attributes, d);
    } // if

    if (data->samplers != NULL)
    {
        for (i = 0; i < data->sampler_count; i++)
        {
            if (data->samplers[i].name != NULL)
                f((void *) data->samplers[i].name, d);
        } // for
        f((void *) data->samplers, d);
    } // if

    if ((data->error != NULL) && (data->error != out_of_mem_str))
        f((void *) data->error, d);

    f(data, d);
} // MOJOSHADER_freeParseData


int MOJOSHADER_version(void)
{
    return MOJOSHADER_VERSION;
} // MOJOSHADER_version

// end of mojoshader.c ...