mojoshader_assembler.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.
 */

#define __MOJOSHADER_INTERNAL__ 1
#include "mojoshader_internal.h"

#define DEBUG_TOKENIZER 0

// !!! FIXME: no #define support yet.

/*

Ideally, we want this, I guess:
struct TokenizerContext
{
    const char *source;
    int on_endline;
    unsigned int linenum;
    char prevchar;
    char token[64];
    char pushedback;
    uint32 tokenbuf[16];
    int keywords;
};

...and replace all that in Context with one TokenizerContext.

tokenize() will then work with these directly (and nexttoken() will call it
 with &ctx->tokenizerctx).

Then let these be stack-allocated as needed.

(keywords) will tell the tokenizer to give full keywords, so "dp3" is one
 token instead of two ("dp" and "3"). This will be the new behaviour, but you
 could then take a whole keyword that needs to be split (like "vs_2_0"), and
 make it the source on a stack-allocated tokenizer, with keywords set to zero.

*/


typedef struct Context Context;

// Context...this is state that changes as we assemble a shader...
struct Context
{
    MOJOSHADER_malloc malloc;
    MOJOSHADER_free free;
    void *malloc_data;
    const char *failstr;
    const char *source;
    int started_parsing;
    MOJOSHADER_shaderType shader_type;
    uint8 major_ver;
    uint8 minor_ver;
    int on_endline;
    unsigned int linenum;
    char prevchar;
    char token[64];
    char pushedback;
    uint32 tokenbuf[16];
    int tokenbufpos;
    DestArgInfo dest_arg;
    uint32 *output;
    uint32 *token_to_line;
    size_t output_len;
    size_t output_allocation;
};


// Convenience functions for allocators...

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

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 = 0;
        va_list ap;
        va_start(ap, fmt);
        const int len = vsnprintf(&scratch, sizeof (scratch), fmt, ap);
        va_end(ap);

        char *failstr = (char *) Malloc(ctx, len + 1);
        if (failstr != NULL)
        {
            va_start(ap, fmt);
            vsnprintf(failstr, len + 1, fmt, ap);  // rebuild it.
            va_end(ap);
            ctx->failstr = failstr;
        } // if
    } // if

    return FAIL;
} // failf

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

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


// 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_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_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 int ui32fromstr(const char *str, uint32 *ui32)
{
    //*ui32 = (uint32) atoi(minstr);
    char *endptr = NULL;
    const long val = strtol(str, &endptr, 10);
    *ui32 = (uint32) val;
    return ((val >= 0) && (*str != '\0') && (*endptr == '\0'));
} // ui32fromstr


static void output_token_noswap(Context *ctx, const uint32 token)
{
    if (isfail(ctx))
        return;

    if (ctx->output_len >= ctx->output_allocation)
    {
        const size_t output_alloc_bump = 1024;  // that's tokens, not bytes.
        const size_t newsize = ctx->output_allocation + output_alloc_bump;
        void *ptr;

        ptr = Malloc(ctx, newsize * sizeof (uint32));
        if (ptr == NULL)
            return;
        if (ctx->output_len > 0)
            memcpy(ptr, ctx->output, ctx->output_len * sizeof (uint32));
        Free(ctx, ctx->output);
        ctx->output = (uint32 *) ptr;

        ptr = Malloc(ctx, newsize * sizeof (uint32));
        if (ptr == NULL)
            return;
        if (ctx->output_len > 0)
            memcpy(ptr, ctx->token_to_line, ctx->output_len * sizeof (uint32));
        Free(ctx, ctx->token_to_line);
        ctx->token_to_line = (uint32 *) ptr;

        ctx->output_allocation = newsize;
    } // if

    ctx->output[ctx->output_len] = token;
    ctx->token_to_line[ctx->output_len] = ctx->linenum;
    ctx->output_len++;
} // output_token_noswap


static inline void output_token(Context *ctx, const uint32 token)
{
    output_token_noswap(ctx, SWAP32(token));
} // output_token


static void output_comment_bytes(Context *ctx, const uint8 *buf, size_t len)
{
    if (len > (0xFFFF * 4))  // length is stored as token count, in 16 bits.
        fail(ctx, "Comment field is too big");
    else if (!isfail(ctx))
    {
        const uint32 tokencount = (len / 4) + ((len % 4) ? 1 : 0);
        output_token(ctx, 0xFFFE | (tokencount << 16));
        while (len >= 4)
        {
            output_token_noswap(ctx, *((const uint32 *) buf));
            len -= 4;
            buf += 4;
        } // while

        if (len > 0)  // handle spillover...
        {
            union { uint8 ui8[4]; uint32 ui32; } overflow;
            overflow.ui32 = 0;
            memcpy(overflow.ui8, buf, len);
            output_token_noswap(ctx, overflow.ui32);
        } // if
    } // else if
} // output_comment_bytes


static inline void output_comment_string(Context *ctx, const char *str)
{
    output_comment_bytes(ctx, (const uint8 *) str, strlen(str));
} // output_comment_string


static int _tokenize(Context *ctx)
{
    int idx = 0;

    if (isfail(ctx))
        return FAIL;

    if (ctx->pushedback)
    {
        ctx->pushedback = 0;
        return NOFAIL;
    } // if

    if (ctx->on_endline)
    {
        ctx->on_endline = 0;
        ctx->linenum++;  // passed a newline, update.
    } // if

    while (1)
    {
        // !!! FIXME: carefully crafted (but legal) comments can trigger this.
        if (idx >= sizeof (ctx->token))
            return fail(ctx, "buffer overflow");

        char ch = *ctx->source;
        if (ch == '\t')
            ch = ' ';  // collapse tabs into single spaces.
        else if (ch == '\r')
        {
            if (ctx->source[1] == '\n')
               continue;  // ignore '\r' if this is "\r\n" ...
            ch = '\n';
        } // else if

        if ((ch >= '0') && (ch <= '9'))
        {
            // starting a number, but rest of current token was not number.
            if ((idx > 0) && ((ctx->prevchar < '0') || (ctx->prevchar > '9')))
            {
                ctx->token[idx++] = '\0';
                return NOFAIL;
            } // if
        } // if
        else
        {
            // starting a non-number, but rest of current token was numbers.
            if ((idx > 0) && ((ctx->prevchar >= '0') && (ctx->prevchar <= '9')))
            {
                ctx->token[idx++] = '\0';
                return NOFAIL;
            } // if
        } // else

        switch (ch)
        {
            case '/':
            case ';':  // !!! FIXME: comment, right?
                if (idx != 0)  // finish off existing token.
                    ctx->token[idx] = '\0';
                else
                {
                    ctx->token[idx++] = ch;
                    ctx->source++;
                    if ((ch == '/') && (*ctx->source == '/'))
                    {
                        ctx->token[idx++] = '/';
                        ctx->source++;
                    } // if
                    ctx->token[idx++] = '\0';
                } // else
                return NOFAIL;

            case ' ':
                if (ctx->prevchar == ' ')
                    break;   // multiple whitespace collapses into one.
                // intentional fall-through...

            case '_':
            case '[':
            case ']':
            case '(':
            case ')':
            case '!':
            case '+':
            case '-':
            case ',':
            case '.':
            case '\n':
                if (idx != 0)  // finish off existing token.
                    ctx->token[idx] = '\0';
                else  // this is a token in itself.
                {
                    if (ch == '\n')
                        ctx->on_endline = 1;
                    ctx->source++;
                    ctx->token[idx++] = ch;
                    ctx->token[idx++] = '\0';
                } // else
                return NOFAIL;

            case '\0':
                ctx->token[idx] = '\0';
                if (idx != 0)  // had any chars? It's a token.
                    return NOFAIL;
                return END_OF_STREAM;

            default:
                ctx->source++;
                ctx->token[idx++] = ch;
                break;
        } // switch

        ctx->prevchar = ch;
    } // while

    return fail(ctx, "???");  // shouldn't hit this.
} // _tokenize


static inline int tokenize(Context *ctx)
{
    const int rc = _tokenize(ctx);
    #if DEBUG_TOKENIZER
    printf("TOKENIZE: %s '%s'\n",
           (rc == END_OF_STREAM) ? "END_OF_STREAM" :
           (rc == FAIL) ? "FAIL" :
           (rc == NOFAIL) ? "NOFAIL" : "???",
           (ctx->token[0] == '\n') ? "\\n" : ctx->token);
    #endif
    return rc;
} // tokenize


static inline int pushback(Context *ctx)
{
    #if DEBUG_TOKENIZER
    printf("PUSHBACK\n");
    #endif

    if (ctx->pushedback)
        return fail(ctx, "BUG: Double pushback in parser");
    else
        ctx->pushedback = 1;

    return NOFAIL;
} // pushback


static int nexttoken(Context *ctx, const int ignoreeol,
                     const int ignorewhitespace, const int eolok,
                     const int eosok)
{
    int rc = NOFAIL;

    while ((rc = tokenize(ctx)) == NOFAIL)
    {
        if (strcmp(ctx->token, "\n") == 0)
        {
            if (ignoreeol)
                continue;
            else if (!eolok)
                return fail(ctx, "Unexpected EOL");
        } // if

        else if (strcmp(ctx->token, " ") == 0)
        {
            if (ignorewhitespace)
                continue;
        } // else if

        // skip comments...
        else if ((strcmp(ctx->token, "//") == 0) || (strcmp(ctx->token, ";") == 0))
        {
            while ((rc = tokenize(ctx)) == NOFAIL)
            {
                if (strcmp(ctx->token, "\n") == 0)
                {
                    pushback(ctx);
                    break;
                } // if
            } // while
            continue;  // pick up from newline, go again.
        } // if

        break;
    } // while

    #if DEBUG_TOKENIZER
    printf("NEXTTOKEN: %s '%s'\n",
           (rc == END_OF_STREAM) ? "END_OF_STREAM" :
           (rc == FAIL) ? "FAIL" :
           (rc == NOFAIL) ? "NOFAIL" : "???",
           (ctx->token[0] == '\n') ? "\\n" : ctx->token);
    #endif

    if ((rc == END_OF_STREAM) && (!eosok))
        return fail(ctx, "Unexpected EOF");

    return rc;
} // nexttoken


static int require_endline(Context *ctx)
{
    const int rc = nexttoken(ctx, 0, 1, 1, 1);
    if (rc == FAIL)
        return FAIL;
    else if (rc == END_OF_STREAM)
        return NOFAIL;  // we'll call this an EOL.
    else if (strcmp(ctx->token, "\n") != 0)
        return fail(ctx, "Endline expected");
    return NOFAIL;
} // require_endline


static int require_comma(Context *ctx)
{
    const int rc = nexttoken(ctx, 0, 1, 0, 0);
    if (rc == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, ",") != 0)
        return fail(ctx, "Comma expected");
    return NOFAIL;
} // require_comma


static int parse_register_name(Context *ctx, RegisterType *rtype, int *rnum)
{
    if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;

    // !!! FIXME: some of these registers are only valid for some shader types.
    int neednum = 1;
    int regnum = 0;
    const char *t = ctx->token;
    RegisterType regtype = REG_TYPE_TEMP;
    if (strcasecmp(t, "r") == 0)
        regtype = REG_TYPE_TEMP;
    else if (strcasecmp(t, "v") == 0)
        regtype = REG_TYPE_INPUT;
    else if (strcasecmp(t, "c") == 0)
        regtype = REG_TYPE_CONST;
    else if (strcasecmp(t, "i") == 0)
        regtype = REG_TYPE_CONSTINT;
    else if (strcasecmp(t, "b") == 0)
        regtype = REG_TYPE_CONSTBOOL;
    else if (strcasecmp(t, "oC") == 0)
        regtype = REG_TYPE_COLOROUT;
    else if (strcasecmp(t, "s") == 0)
        regtype = REG_TYPE_SAMPLER;
    else if (strcasecmp(t, "oD") == 0)
        regtype = REG_TYPE_ATTROUT;
    else if (strcasecmp(t, "l") == 0)
        regtype = REG_TYPE_LABEL;
    else if (strcasecmp(t, "p") == 0)
        regtype = REG_TYPE_PREDICATE;
    else if (strcasecmp(t, "oDepth") == 0)
    {
        regtype = REG_TYPE_DEPTHOUT;
        neednum = 0;
    } // else if
    else if (strcasecmp(t, "aL") == 0)
    {
        regtype = REG_TYPE_LOOP;
        neednum = 0;
    } // else if
    else if (strcasecmp(t, "o") == 0)
    {
        if (!shader_is_vertex(ctx) || !shader_version_atleast(ctx, 3, 0))
            return fail(ctx, "Output register not valid in this shader type");
        regtype = REG_TYPE_OUTPUT;
    } // else if
    else if (strcasecmp(t, "oT") == 0)
    {
        if (shader_is_vertex(ctx) && shader_version_atleast(ctx, 3, 0))
            return fail(ctx, "Output register not valid in this shader type");
        regtype = REG_TYPE_OUTPUT;
    } // else if
    else if (strcasecmp(t, "a") == 0)
    {
        if (!shader_is_vertex(ctx))
            return fail(ctx, "Address register only valid in vertex shaders.");
        regtype = REG_TYPE_ADDRESS;
    } // else if
    else if (strcasecmp(t, "t") == 0)
    {
        if (!shader_is_pixel(ctx))
            return fail(ctx, "Address register only valid in pixel shaders.");
        regtype = REG_TYPE_ADDRESS;
    } // else if
    else if (strcasecmp(t, "vPos") == 0)
    {
        regtype = REG_TYPE_MISCTYPE;
        regnum = (int) MISCTYPE_TYPE_POSITION;
        neednum = 0;
    } // else if
    else if (strcasecmp(t, "vFace") == 0)
    {
        regtype = REG_TYPE_MISCTYPE;
        regnum = (int) MISCTYPE_TYPE_FACE;
        neednum = 0;
    } // else if
    else if (strcasecmp(t, "oPos") == 0)
    {
        regtype = REG_TYPE_RASTOUT;
        regnum = (int) RASTOUT_TYPE_POSITION;
        neednum = 0;
    } // else if
    else if (strcasecmp(t, "oFog") == 0)
    {
        regtype = REG_TYPE_RASTOUT;
        regnum = (int) RASTOUT_TYPE_FOG;
        neednum = 0;
    } // else if
    else if (strcasecmp(t, "oPts") == 0)
    {
        regtype = REG_TYPE_RASTOUT;
        regnum = (int) RASTOUT_TYPE_POINT_SIZE;
        neednum = 0;
    } // else if
        
    //case REG_TYPE_TEMPFLOAT16:  // !!! FIXME: don't know this asm string

    else
    {
        return fail(ctx, "expected register type");
    } // else

    if (neednum)
    {
        // cheat the pushback.
        const char *origsrc = ctx->source;
        const int origonendline = ctx->on_endline;
        const int origlinenum = ctx->linenum;
        const int origprevchar = ctx->prevchar;

        if (nexttoken(ctx, 0, 1, 1, 1) == FAIL)
            return FAIL;
        else if (strcmp(ctx->token, "[") == 0)
            neednum = 0;

        ctx->source = origsrc;
        ctx->on_endline = origonendline;
        ctx->linenum = origlinenum;
        ctx->prevchar = origprevchar;
    } // if

    if (neednum)
    {
        if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
            return FAIL;

        uint32 ui32 = 0;
        if (!ui32fromstr(ctx->token, &ui32))
            return fail(ctx, "Invalid register index");
        regnum = (int) ui32;
    } // if

    // split up REG_TYPE_CONST
    if (regtype == REG_TYPE_CONST)
    {
        if (regnum < 2048)
        {
            regtype = REG_TYPE_CONST;
            regnum -= 0;
        } // if
        else if (regnum < 4096)
        {
            regtype = REG_TYPE_CONST2;
            regnum -= 2048;
        } // if
        else if (regnum < 6144)
        {
            regtype = REG_TYPE_CONST3;
            regnum -= 4096;
        } // if
        else if (regnum < 8192)
        {
            regtype = REG_TYPE_CONST4;
            regnum -= 6144;
        } // if
        else
        {
            return fail(ctx, "Invalid const register index");
        } // else
    } // if

    *rtype = regtype;
    *rnum = regnum;

    return NOFAIL;
} // parse_register_name


static int set_result_shift(Context *ctx, DestArgInfo *info, const int val)
{
    if (info->result_shift != 0)
        return fail(ctx, "Multiple result shift modifiers");
    info->result_shift = val;
    return NOFAIL;
} // set_result_shift


static int parse_destination_token(Context *ctx, DestArgInfo *info)
{
    memset(info, '\0', sizeof (DestArgInfo));

    // See if there are destination modifiers on the instruction itself...
    while (1)
    {
        if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
            return FAIL;
        else if (strcmp(ctx->token, " ") == 0)
            break;  // done with modifiers.
        else if (strcmp(ctx->token, "_") != 0)
            return fail(ctx, "Expected modifier or whitespace");
        else if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
            return FAIL;
        // !!! FIXME: this can be cleaned up when tokenizer is fixed.
        else if (strcasecmp(ctx->token, "x") == 0)
        {
            if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
                return FAIL;
            else if (strcmp(ctx->token, "2") == 0)
                set_result_shift(ctx, info, 0x1);
            else if (strcmp(ctx->token, "4") == 0)
                set_result_shift(ctx, info, 0x2);
            else if (strcmp(ctx->token, "8") == 0)
                set_result_shift(ctx, info, 0x3);
            else
                return fail(ctx, "Expected modifier");
        } // else if
        // !!! FIXME: this can be cleaned up when tokenizer is fixed.
        else if (strcasecmp(ctx->token, "d") == 0)
        {
            if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
                return FAIL;
            else if (strcmp(ctx->token, "8") == 0)
                set_result_shift(ctx, info, 0xD);
            else if (strcmp(ctx->token, "4") == 0)
                set_result_shift(ctx, info, 0xE);
            else if (strcmp(ctx->token, "2") == 0)
                set_result_shift(ctx, info, 0xF);
            else
                return fail(ctx, "Expected modifier");
        } // else if
        else if (strcasecmp(ctx->token, "sat") == 0)
            info->result_mod |= MOD_SATURATE;
        else if (strcasecmp(ctx->token, "pp") == 0)
            info->result_mod |= MOD_PP;
        else if (strcasecmp(ctx->token, "centroid") == 0)
            info->result_mod |= MOD_CENTROID;
        else
            return fail(ctx, "Expected modifier");
    } // while

    if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;

    // !!! FIXME: predicates.
    if (strcmp(ctx->token, "(") == 0)
        return fail(ctx, "Predicates unsupported at this time");
    pushback(ctx);  // parse_register_name calls nexttoken().

    if (parse_register_name(ctx, &info->regtype, &info->regnum) == FAIL)
        return FAIL;

    if (nexttoken(ctx, 0, 1, 1, 1) == FAIL)
        return FAIL;

    // !!! FIXME: can dest registers do relative addressing?

    if (strcmp(ctx->token, ".") != 0)
    {
        info->writemask = 0xF;
        info->writemask0 = info->writemask1 = info->writemask2 = info->writemask3 = 1;
        pushback(ctx);  // no explicit writemask; do full mask.
    } // if
    else if (scalar_register(ctx->shader_type, info->regtype, info->regnum))
        return fail(ctx, "Writemask specified for scalar register");
    else if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (ctx->token[0] == '\0')
        return fail(ctx, "Invalid writemask");
    else
    {
        char *ptr = ctx->token;
        info->writemask0 = info->writemask1 = info->writemask2 = info->writemask3 = 0;
        if (*ptr == 'x') { info->writemask0 = 1; ptr++; }
        if (*ptr == 'y') { info->writemask1 = 1; ptr++; }
        if (*ptr == 'z') { info->writemask2 = 1; ptr++; }
        if (*ptr == 'w') { info->writemask3 = 1; ptr++; }
        if ((ptr == ctx->token) && (shader_is_pixel(ctx)))
        {
            if (*ptr == 'r') { info->writemask0 = 1; ptr++; }
            if (*ptr == 'g') { info->writemask1 = 1; ptr++; }
            if (*ptr == 'b') { info->writemask2 = 1; ptr++; }
            if (*ptr == 'a') { info->writemask3 = 1; ptr++; }
        } // if

        if (*ptr != '\0')
            return fail(ctx, "Invalid writemask");

        info->writemask = ( ((info->writemask0 & 0x1) << 0) |
                            ((info->writemask1 & 0x1) << 1) |
                            ((info->writemask2 & 0x1) << 2) |
                            ((info->writemask3 & 0x1) << 3) );
    } // else

    info->orig_writemask = info->writemask;

    if (ctx->tokenbufpos >= STATICARRAYLEN(ctx->tokenbuf))
        return fail(ctx, "Too many tokens");

    ctx->tokenbuf[ctx->tokenbufpos++] =
            ( ((((uint32) 1)) << 31) |
              ((((uint32) info->regnum) & 0x7ff) << 0) |
              ((((uint32) info->relative) & 0x1) << 13) |
              ((((uint32) info->result_mod) & 0xF) << 20) |
              ((((uint32) info->result_shift) & 0xF) << 24) |
              ((((uint32) info->writemask) & 0xF) << 16) |
              ((((uint32) info->regtype) & 0x7) << 28) |
              ((((uint32) info->regtype) & 0x18) << 8) );

    return 1;
} // parse_destination_token


static void set_source_mod(Context *ctx, const int negate,
                           const SourceMod norm, const SourceMod negated,
                           SourceMod *srcmod)
{
    if ( (*srcmod != SRCMOD_NONE) || (negate && (negated == SRCMOD_NONE)) )
        fail(ctx, "Incompatible source modifiers");
    else
        *srcmod = ((negate) ? negated : norm);
} // set_source_mod


static int parse_source_token_maybe_relative(Context *ctx, const int relok)
{
    int retval = 1;

    if (ctx->tokenbufpos >= STATICARRAYLEN(ctx->tokenbuf))
        return fail(ctx, "Too many tokens");

    // mark this now, so optional relative addressing token is placed second.
    uint32 *token = &ctx->tokenbuf[ctx->tokenbufpos++];

    SourceMod srcmod = SRCMOD_NONE;
    int negate = 0;
    if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, "1") == 0)
    {
        if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
            return FAIL;
        else if (strcmp(ctx->token, "-") != 0)
            return fail(ctx, "Unexpected value");
        else
            srcmod = SRCMOD_COMPLEMENT;
    } // else
    else if (strcmp(ctx->token, "!") == 0)
        srcmod = SRCMOD_NOT;
    else if (strcmp(ctx->token, "-") == 0)
        negate = 1;
    else
        pushback(ctx);

    RegisterType regtype;
    int regnum;
    if (parse_register_name(ctx, &regtype, &regnum) == FAIL)
        return FAIL;
    else if (nexttoken(ctx, 0, 1, 1, 1) == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, "_") != 0)
        pushback(ctx);
    else if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if (strcasecmp(ctx->token, "bias") == 0)
        set_source_mod(ctx, negate, SRCMOD_BIAS, SRCMOD_BIASNEGATE, &srcmod);
    else if (strcasecmp(ctx->token, "bx2") == 0)
        set_source_mod(ctx, negate, SRCMOD_SIGN, SRCMOD_SIGNNEGATE, &srcmod);
    else if (strcasecmp(ctx->token, "x2") == 0)
        set_source_mod(ctx, negate, SRCMOD_X2, SRCMOD_X2NEGATE, &srcmod);
    else if (strcasecmp(ctx->token, "dz") == 0)
        set_source_mod(ctx, negate, SRCMOD_DZ, SRCMOD_NONE, &srcmod);
    else if (strcasecmp(ctx->token, "dw") == 0)
        set_source_mod(ctx, negate, SRCMOD_DW, SRCMOD_NONE, &srcmod);
    else if (strcasecmp(ctx->token, "abs") == 0)
        set_source_mod(ctx, negate, SRCMOD_ABS, SRCMOD_ABSNEGATE, &srcmod);
    else
        return fail(ctx, "Invalid source modifier");

    if (nexttoken(ctx, 0, 1, 1, 1) == FAIL)
        return FAIL;

    uint32 relative = 0;
    if (strcmp(ctx->token, "[") != 0)
        pushback(ctx);  // not relative addressing?
    else if (!relok)
        return fail(ctx, "Relative addressing not permitted here.");
    else
    {
        const int rc = parse_source_token_maybe_relative(ctx, 0);
        if (rc == FAIL)
            return FAIL;
        retval += rc;
        relative = 1;
        if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
            return FAIL;
        else if (strcmp(ctx->token, "+") != 0)
            pushback(ctx);
        else if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
            return FAIL;
        else
        {
            if (regnum != 0)  // !!! FIXME: maybe c3[a0.x + 5] is legal and becomes c[a0.x + 8] ?
                fail(ctx, "Relative addressing with explicit register number.");
            uint32 ui32 = 0;
            if (!ui32fromstr(ctx->token, &ui32))
                return fail(ctx, "Invalid relative addressing offset");
            regnum += (int) ui32;
        } // else

        if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
            return FAIL;
        else if (strcmp(ctx->token, "]") != 0)
            return fail(ctx, "Expected ']'");
    } // else

    if (nexttoken(ctx, 0, 1, 1, 1) == FAIL)
        return FAIL;

    uint32 swizzle = 0;
    if (strcmp(ctx->token, ".") != 0)
    {
        swizzle = 0xE4;  // 0xE4 == 11100100 ... 0 1 2 3. No swizzle.
        pushback(ctx);  // no explicit writemask; do full mask.
    } // if
    else if (scalar_register(ctx->shader_type, regtype, regnum))
        return fail(ctx, "Swizzle specified for scalar register");
    else if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (ctx->token[0] == '\0')
        return fail(ctx, "Invalid swizzle");
    else
    {
        // deal with shortened form (.x = .xxxx, etc).
        if (ctx->token[1] == '\0')
            ctx->token[1] = ctx->token[2] = ctx->token[3] = ctx->token[0];
        else if (ctx->token[2] == '\0')
            ctx->token[2] = ctx->token[3] = ctx->token[1];
        else if (ctx->token[3] == '\0')
            ctx->token[3] = ctx->token[2];
        else if (ctx->token[4] != '\0')
            return fail(ctx, "Invalid swizzle");
        ctx->token[4] = '\0';

        uint32 val;
        int saw_xyzw = 0;
        int saw_rgba = 0;
        int i;
        for (i = 0; i < 4; i++)
        {
            const int component = (int) ctx->token[i];
            switch (component)
            {
                case 'x': val = 0; saw_xyzw = 1; break;
                case 'y': val = 1; saw_xyzw = 1; break;
                case 'z': val = 2; saw_xyzw = 1; break;
                case 'w': val = 3; saw_xyzw = 1; break;
                case 'r': val = 0; saw_rgba = 1; break;
                case 'g': val = 1; saw_rgba = 1; break;
                case 'b': val = 2; saw_rgba = 1; break;
                case 'a': val = 3; saw_rgba = 1; break;
                default: return fail(ctx, "Invalid swizzle");
            } // switch
            swizzle |= (val << (i * 2));
        } // for

        if (saw_xyzw && saw_rgba)
            return fail(ctx, "Invalid swizzle");
    } // else

    *token = ( ((((uint32) 1)) << 31) |
               ((((uint32) regnum) & 0x7ff) << 0) |
               ((((uint32) relative) & 0x1) << 13) |
               ((((uint32) swizzle) & 0xFF) << 16) |
               ((((uint32) srcmod) & 0xF) << 24) |
               ((((uint32) regtype) & 0x7) << 28) |
               ((((uint32) regtype) & 0x18) << 8) );

    return retval;
} // parse_source_token_maybe_relative


static inline int parse_source_token(Context *ctx)
{
    return parse_source_token_maybe_relative(ctx, 1);
} // parse_source_token


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


static int parse_num(Context *ctx, const int floatok, uint32 *token)
{
    int32 negative = 1;
    union { float f; int32 si32; uint32 ui32; } cvt;
    cvt.si32 = 0;

    if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, "-") == 0)
        negative = -1;
    else
        pushback(ctx);

    uint32 val = 0;
    if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (!ui32fromstr(ctx->token, &val))
        return fail(ctx, "Expected number");

    uint32 fraction = 0;
    if (nexttoken(ctx, 0, 1, 1, 1) == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, ".") != 0)
        pushback(ctx);  // whole number
    else if (!floatok)
        return fail(ctx, "Expected whole number");
    else if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (!ui32fromstr(ctx->token, &fraction))
        return fail(ctx, "Expected number");

    uint32 exponent = 0;
    int negexp = 0;
    if (nexttoken(ctx, 0, 1, 1, 1) == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, "e") != 0)
        pushback(ctx);
    else if (!floatok)
        return fail(ctx, "Exponent on whole number");  // !!! FIXME: illegal?
    else if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else
    {
        if (strcmp(ctx->token, "-") != 0)
            pushback(ctx);
        else
            negexp = 1;

        if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
            return FAIL;
        else if (!ui32fromstr(ctx->token, &exponent))
            return fail(ctx, "Expected exponent");
    } // else

    if (!floatok)
        cvt.si32 = ((int32) val) * negative;
    else
    {
        // !!! FIXME: this is lame.
        char buf[128];
        snprintf(buf, sizeof (buf), "%s%u.%u", (negative < 0) ? "-" : "",
                 (uint) val, (uint) fraction);
        sscanf(buf, "%f", &cvt.f);
        cvt.f *= (float) negative;

        if (exponent)
        {
            int i;
            if (negexp)
            {
                for (i = 0; i > exponent; i--)
                    cvt.f /= 10.0f;
            } // if
            else
            {
                for (i = 0; i < exponent; i++)
                    cvt.f *= 10.0f;
            } // else
        } // if
    } // else

    *token = cvt.ui32;
    return NOFAIL;
} // parse_num


static int parse_args_DEFx(Context *ctx, const int isflt)
{
    if (parse_destination_token(ctx, &ctx->dest_arg) == FAIL)
        return FAIL;
    else if (require_comma(ctx) == FAIL)
        return FAIL;
    else if (parse_num(ctx, isflt, &ctx->tokenbuf[ctx->tokenbufpos++]) == FAIL)
        return FAIL;
    else if (require_comma(ctx) == FAIL)
        return FAIL;
    else if (parse_num(ctx, isflt, &ctx->tokenbuf[ctx->tokenbufpos++]) == FAIL)
        return FAIL;
    else if (require_comma(ctx) == FAIL)
        return FAIL;
    else if (parse_num(ctx, isflt, &ctx->tokenbuf[ctx->tokenbufpos++]) == FAIL)
        return FAIL;
    else if (require_comma(ctx) == FAIL)
        return FAIL;
    else if (parse_num(ctx, isflt, &ctx->tokenbuf[ctx->tokenbufpos++]) == FAIL)
        return FAIL;
    return 6;
} // parse_args_DEFx


static int parse_args_DEF(Context *ctx)
{
    return parse_args_DEFx(ctx, 1);
} // parse_args_DEF


static int parse_args_DEFI(Context *ctx)
{
    return parse_args_DEFx(ctx, 0);
} // parse_args_DEFI


static int parse_args_DEFB(Context *ctx)
{
    if (parse_destination_token(ctx, &ctx->dest_arg) == FAIL)
        return FAIL;
    else if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, ",") != 0)
        return fail(ctx, "Expected ','");
    else if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
        return FAIL;
    else if (strcasecmp(ctx->token, "true") == 0)
        ctx->tokenbuf[ctx->tokenbufpos++] = 1;
    else if (strcasecmp(ctx->token, "false") == 0)
        ctx->tokenbuf[ctx->tokenbufpos++] = 0;
    else
        return fail(ctx, "Expected 'true' or 'false'");
    return 3;
} // parse_args_DEFB


static int parse_dcl_usage(Context *ctx, uint32 *val, int *issampler)
{
    int i;
    static const char *samplerusagestrs[] = { "2d", "cube", "volume" };
    static const char *usagestrs[] = {
        "position", "blendweight", "blendindices", "normal", "psize",
        "texcoord", "tangent", "binormal", "tessfactor", "positiont",
        "color", "fog", "depth", "sample"
    };
    static const char *ignorestrs[] = { "pp", "centroid", "saturate" };

    // !!! FIXME: we need to clean this out in the tokenizer.
    char token[sizeof (ctx->token)];
    strcpy(token, ctx->token);
    if (strcmp(token, "2") == 0)  // "2d" is two tokens.
    {
        if (nexttoken(ctx, 0, 0, 1, 1) == FAIL)
            return FAIL;
        else if (strcasecmp(ctx->token, "d") != 0)
            pushback(ctx);
        else
            strcpy(token, "2d");
    } // if

    for (i = 0; i < STATICARRAYLEN(usagestrs); i++)
    {
        if (strcasecmp(usagestrs[i], token) == 0)
        {
            *issampler = 0;
            *val = i;
            return NOFAIL;
        } // if
    } // for

    for (i = 0; i < STATICARRAYLEN(samplerusagestrs); i++)
    {
        if (strcasecmp(samplerusagestrs[i], token) == 0)
        {
            *issampler = 1;
            *val = i + 2;
            return NOFAIL;
        } // if
    } // for

    // !!! FIXME: this probably isn't the smartest way to handle this.
    *issampler = 0;
    *val = 0;
    for (i = 0; i < STATICARRAYLEN(ignorestrs); i++)
    {
        if (strcasecmp(ignorestrs[i], token) == 0)
        {
            ctx->source -= strlen(token);  // !!! FIXME: hack to move back
            strcpy(ctx->token, "_");  // !!! FIXME: hack to move back
            pushback(ctx);  // !!! FIXME: hack to move back
            return NOFAIL;  // if you have "dcl_pp", then "_pp" isn't a usage.
        } // if
    } // for

    return FAIL;
} // parse_dcl_usage


static int parse_args_DCL(Context *ctx)
{
    int issampler = 0;
    uint32 usage = 0;
    uint32 index = 0;

    ctx->tokenbufpos++;  // save a spot for the usage/index token.

    if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if (strcmp(ctx->token, " ") == 0)
        pushback(ctx);
    else if (strcmp(ctx->token, "_") != 0)
        return fail(ctx, "Expected register or usage");
    else if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if (parse_dcl_usage(ctx, &usage, &issampler) == FAIL)
        return FAIL;

    if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if ((strcmp(ctx->token, " ") == 0) || (strcmp(ctx->token, "_") == 0))
        pushback(ctx);  // parse_destination_token() wants these.
    else if (!ui32fromstr(ctx->token, &index))
        return fail(ctx, "Expected usage index or register");

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

    const int samplerreg = (ctx->dest_arg.regtype == REG_TYPE_SAMPLER);
    if (issampler != samplerreg)
        return fail(ctx, "Invalid usage");
    else if (samplerreg)
        ctx->tokenbuf[0] = (usage << 27) | 0x80000000;
    else
        ctx->tokenbuf[0] = usage | (index << 16) | 0x80000000;

    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);
    return isfail(ctx) ? FAIL : retval;
} // parse_args_S


static int parse_args_SS(Context *ctx)
{
    int retval = 1;
    retval += parse_source_token(ctx);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    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);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    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);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    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);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    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);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    if (require_comma(ctx) == FAIL) return FAIL;
    retval += parse_source_token(ctx);
    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


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

// Lookup table for instruction opcodes...
typedef struct
{
    const char *opcode_string;
    args_function parse_args;
} Instruction;


static const Instruction instructions[] =
{
    #define INSTRUCTION_STATE(op, opstr, s, a, t) { opstr, parse_args_##a },
    #define INSTRUCTION(op, opstr, slots, a, t) { opstr, parse_args_##a },
    #define MOJOSHADER_DO_INSTRUCTION_TABLE 1
    #include "mojoshader_internal.h"
    #undef MOJOSHADER_DO_INSTRUCTION_TABLE
    #undef INSTRUCTION
    #undef INSTRUCTION_STATE
};

static int parse_condition(Context *ctx, uint32 *controls)
{
    if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return 0;
    else if (strcmp(ctx->token, "_") != 0)
    {
        pushback(ctx);
        return 0;
    } // else if

    if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return 0;
    else
    {
        int i;
        static const char *comps[] = {"", "gt", "eq", "ge", "lt", "ne", "le"};
        for (i = 1; i < STATICARRAYLEN(comps); i++)
        {
            if (strcasecmp(ctx->token, comps[i]) == 0)
            {
                *controls = i;
                return 1;
            }
        } // for

        fail(ctx, "Expected comparison token");
        return 0;
    } // else if

    return 0;
} // parse_condition


static inline int valid_instruction_char(const char ch)
{
    return ( ((ch >= 'A') && (ch <= 'Z')) ||
             ((ch >= 'a') && (ch <= 'z')) ||
             ((ch >= '0') && (ch <= '9')) );
} // valid_instruction_char


static int parse_instruction_token(Context *ctx)
{
    int coissue = 0;
    int predicated = 0;
    char opstr[32];

    if (strcmp(ctx->token, "+") == 0)
    {
        if (nexttoken(ctx, 0, 1, 0, 0) == FAIL)
            return FAIL;
        coissue = 1;
    } // if

    // All this tapdance is because some instructions mix letters and numbers,
    //  like "dp4" or "texm3x2depth" and the tokenizer splits words and digits
    //  into separate tokens, which makes parsing registers ("c31") easier.
    opstr[0] = '\0';
    while (1)
    {
        if ( (strlen(opstr) + strlen(ctx->token)) >= (sizeof (opstr)-1) )
            return fail(ctx, "Expected instruction");

        char *ptr;
        for (ptr = ctx->token; *ptr != '\0'; ptr++)
        {
            if (!valid_instruction_char(*ptr))
                break;
        } // for

        if ((ptr == ctx->token) || (*ptr != '\0'))
        {
            pushback(ctx);  // an invalid char or EOS in this token.
            break;
        } // if

        strcat(opstr, ctx->token);

        if (nexttoken(ctx, 0, 0, 1, 1) == FAIL)
            return FAIL;
    } // while

    int i;
    int valid_opcode = 0;
    const Instruction *instruction = NULL;
    for (i = 0; i < STATICARRAYLEN(instructions); i++)
    {
        instruction = &instructions[i];
        if (instruction->opcode_string == NULL)
            continue;  // skip this.
        else if (strcasecmp(opstr, instruction->opcode_string) != 0)
            continue;  // not us.
        valid_opcode = 1;
        break;
    } // for

    uint32 opcode = (uint32) i;
    uint32 controls = 0;

    if (!valid_opcode)
        return failf(ctx, "Unknown instruction '%s'", opstr);

    // This might need to be IFC instead of IF.
    if (strcmp(instruction->opcode_string, "IF") == 0)
    {
        if (parse_condition(ctx, &controls))
            opcode = OPCODE_IFC;
    } // if

    // This might need to be BREAKC instead of BREAK.
    else if (strcmp(instruction->opcode_string, "BREAK") == 0)
    {
        if (parse_condition(ctx, &controls))
            opcode = OPCODE_BREAKC;
    } // else if

    // SETP has a conditional code, always.
    else if (strcmp(instruction->opcode_string, "SETP") == 0)
    {
        if (!parse_condition(ctx, &controls))
            return fail(ctx, "SETP requires a condition");
    } // else if

    instruction = &instructions[opcode];  // ...in case this changed.

    // !!! FIXME: predicated instructions

    ctx->tokenbufpos = 0;

    const int tokcount = instruction->parse_args(ctx);
    if (require_endline(ctx) == FAIL)
        return FAIL;

    // insttoks bits are reserved and should be zero if < SM2.
    const uint32 insttoks = shader_version_atleast(ctx, 2, 0) ? tokcount-1 : 0;

    // write out the instruction token.
    output_token(ctx, ((opcode & 0xFFFF) << 0) |
                      ((controls & 0xFF) << 16) |
                      ((insttoks & 0xF) << 24) |
                      ((coissue) ? 0x40000000 : 0x00000000) |
                      ((predicated) ? 0x10000000 : 0x00000000) );

    // write out the argument tokens.
    for (i = 0; i < (tokcount-1); i++)
        output_token(ctx, ctx->tokenbuf[i]);

    return NOFAIL;
} // parse_instruction_token


static int parse_version_token(Context *ctx)
{
    if (nexttoken(ctx, 1, 1, 0, 0) == FAIL)
        return FAIL;

    uint32 shader_type = 0;
    if (strcasecmp(ctx->token, "vs") == 0)
    {
        ctx->shader_type = MOJOSHADER_TYPE_VERTEX;
        shader_type = 0xFFFE;
    } // if
    else if (strcasecmp(ctx->token, "ps") == 0)
    {
        ctx->shader_type = MOJOSHADER_TYPE_PIXEL;
        shader_type = 0xFFFF;
    } // if
    else
    {
        // !!! FIXME: geometry shaders?
        return fail(ctx, "Expected version string");
    } // else

    uint32 major = 0;
    if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if ((strcmp(ctx->token, "_") != 0) && (strcmp(ctx->token, ".") != 0))
        return fail(ctx, "Expected version string");
    else if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if (!ui32fromstr(ctx->token, &major))
        return fail(ctx, "Expected version string");

    uint32 minor = 0;
    if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if ((strcmp(ctx->token, "_") != 0) && (strcmp(ctx->token, ".") != 0))
        return fail(ctx, "Expected version string");
    else if (nexttoken(ctx, 0, 0, 0, 0) == FAIL)
        return FAIL;
    else if (strcasecmp(ctx->token, "x") == 0)
        minor = 1;
    else if (strcasecmp(ctx->token, "sw") == 0)
        minor = 255;
    else if (!ui32fromstr(ctx->token, &minor))
        return fail(ctx, "Expected version string");

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

    if (require_endline(ctx) == FAIL)
        return FAIL;

    output_token(ctx, (shader_type << 16) | (major << 8) | (minor << 0) );
    return NOFAIL;
} // parse_version_token


static int parse_phase_token(Context *ctx)
{
    if (require_endline(ctx) == FAIL)
        return FAIL;
    output_token(ctx, 0x0000FFFD); // phase token always 0x0000FFFD.
    return NOFAIL;
} // parse_phase_token


static int parse_end_token(Context *ctx)
{
    if (require_endline(ctx) == FAIL)
        return FAIL;
    // We don't emit the end token bits here, since it's valid for a shader
    //  to not specify an "end" string at all; it's implicit, in that case.
    // Instead, we make sure if we see "end" that it's the last thing we see.
    if (nexttoken(ctx, 1, 1, 0, 1) != END_OF_STREAM)
        return fail(ctx, "Content after END");
    return NOFAIL;
} // parse_end_token


static int parse_token(Context *ctx)
{
    const char *t = ctx->token;
    if (strcasecmp(t, "end") == 0)
        return parse_end_token(ctx);
    else if (strcasecmp(t, "phase") == 0)
        return parse_phase_token(ctx);
    return parse_instruction_token(ctx);
} // parse_token


static Context *build_context(const char *source, 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->source = source;
    ctx->linenum = 1;

    return ctx;
} // build_context


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->failstr != NULL) && (ctx->failstr != out_of_mem_str))
            f((void *) ctx->failstr, d);
        if (ctx->output != NULL)
            f(ctx->output, d);
        if (ctx->token_to_line != NULL)
            f(ctx->token_to_line, d);
        f(ctx, d);
    } // if
} // destroy_context


static const MOJOSHADER_parseData *build_failed_assembly(Context *ctx)
{
    MOJOSHADER_parseData *retval = NULL;
    if (!isfail(ctx))
        return NULL;

    retval = (MOJOSHADER_parseData*) Malloc(ctx, sizeof(MOJOSHADER_parseData));
    if (retval == NULL)
        return &out_of_mem_data;

    memset(retval, '\0', sizeof (MOJOSHADER_parseData));
    retval->malloc = (ctx->malloc == internal_malloc) ? NULL : ctx->malloc;
    retval->free = (ctx->free == internal_free) ? NULL : ctx->free;
    retval->malloc_data = ctx->malloc_data;
    retval->error = ctx->failstr;  // we recycle.  :)
    ctx->failstr = NULL;  // don't let this get free()'d too soon.

    if (ctx->started_parsing)
        retval->error_position = ctx->linenum;
    else
        retval->error_position = -1;

    return retval;
} // build_failed_assembly


// API entry point...

const MOJOSHADER_parseData *MOJOSHADER_assemble(const char *source,
                            MOJOSHADER_malloc m, MOJOSHADER_free f, void *d)
{
    MOJOSHADER_parseData *retval = NULL;
    Context *ctx = NULL;

    if ( ((m == NULL) && (f != NULL)) || ((m != NULL) && (f == NULL)) )
        return &out_of_mem_data;  // supply both or neither.

    ctx = build_context(source, m, f, d);
    if (ctx == NULL)
        return &out_of_mem_data;

    // Version token always comes first.
    ctx->started_parsing = 1;
    parse_version_token(ctx);

    ctx->started_parsing = 0;  // make error messages sane if CTAB fails, etc.
    const char *credit = "Generated by MojoShader assembler revision "
                         MOJOSHADER_CHANGESET
                         ", http://icculus.org/mojoshader/";
    output_comment_string(ctx, credit);

    // !!! FIXME: insert CTAB here.

    ctx->started_parsing = 1;

    // parse out the rest of the tokens after the version token...
    while (nexttoken(ctx, 1, 1, 0, 1) == NOFAIL)
        parse_token(ctx);

    output_token(ctx, 0x0000FFFF);   // end token always 0x0000FFFF.

    if (isfail(ctx))
        retval = (MOJOSHADER_parseData *) build_failed_assembly(ctx);
    else
    {
        // This validates the shader; there are lots of things that are
        //  invalid, but will successfully parse in the assembler, generating
        //  bad bytecode; this will catch them without us having to
        //  duplicate most of the validation here.
        // It also saves us the trouble of duplicating all the other work,
        //  like setting up the uniforms list, etc.
        retval = (MOJOSHADER_parseData *)
                        MOJOSHADER_parse(MOJOSHADER_PROFILE_BYTECODE,
                                      (const unsigned char *) ctx->output,
                                      ctx->output_len * sizeof (uint32),
                                      NULL, 0, m, f, d);

        // on error, map the bytecode back to a line number.
        if (retval->error_position >= 0)
        {
            assert(retval != &out_of_mem_data);
            const int pos = retval->error_position / sizeof (uint32);
            if (pos < ctx->output_len)
                retval->error_position = ctx->token_to_line[pos];
            else
                retval->error_position = -1;  // oh well.
        } // if
    } // if

    destroy_context(ctx);
    return retval;
} // MOJOSHADER_assemble


// end of mojoshader_assembler.c ...