/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Library General Public

    License as published by the Free Software Foundation; either

    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public

    License along with this library; if not, write to the Free

    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga

    slouken@devolution.com

*/

#ifdef SAVE_RCSID

static char rcsid =

 "@(#) $Id$";

#endif

/* This a stretch blit implementation based on ideas given to me by

   Tomasz Cejner - thanks! :)

   April 27, 2000 - Sam Lantinga

*/

#include "SDL_error.h"

#include "SDL_video.h"

#include "SDL_blit.h"

/* This isn't ready for general consumption yet - it should be folded

   into the general blitting mechanism.

*/

#if (defined(WIN32) && !defined(_M_ALPHA) && !defined(_WIN32_WCE)) || \

    defined(i386) && defined(__GNUC__) && defined(USE_ASMBLIT)

#define USE_ASM_STRETCH

#endif

#ifdef USE_ASM_STRETCH

#if defined(WIN32) || defined(i386)

#define PREFIX16	0x66

#define STORE_BYTE	0xAA

#define STORE_WORD	0xAB

#define LOAD_BYTE	0xAC

#define LOAD_WORD	0xAD

#define RETURN		0xC3

#else

#error Need assembly opcodes for this architecture

#endif

#if defined(__ELF__) && defined(__GNUC__)

extern unsigned char _copy_row[4096] __attribute__ ((alias ("copy_row")));

#endif

static unsigned char copy_row[4096];

static int generate_rowbytes(int src_w, int dst_w, int bpp)

{

	static struct {

		int bpp;

		int src_w;

		int dst_w;

	} last;

	int i;

	int pos, inc;

	unsigned char *eip;

	unsigned char load, store;

	/* See if we need to regenerate the copy buffer */

	if ( (src_w == last.src_w) &&

	     (dst_w == last.src_w) && (bpp == last.bpp) ) {

		return(0);

	}

	last.bpp = bpp;

	last.src_w = src_w;

	last.dst_w = dst_w;

	switch (bpp) {

	    case 1:

		load = LOAD_BYTE;

		store = STORE_BYTE;

		break;

	    case 2:

	    case 4:

		load = LOAD_WORD;

		store = STORE_WORD;

		break;

	    default:

		SDL_SetError("ASM stretch of %d bytes isn't supported\n", bpp);

		return(-1);

	}

	pos = 0x10000;

	inc = (src_w << 16) / dst_w;

	eip = copy_row;

	for ( i=0; i<dst_w; ++i ) {

		while ( pos >= 0x10000L ) {

			if ( bpp == 2 ) {

				*eip++ = PREFIX16;

			}

			*eip++ = load;

			pos -= 0x10000L;

		}

		if ( bpp == 2 ) {

			*eip++ = PREFIX16;

		}

		*eip++ = store;

		pos += inc;

	}

	*eip++ = RETURN;

	/* Verify that we didn't overflow (too late) */

	if ( eip > (copy_row+sizeof(copy_row)) ) {

		SDL_SetError("Copy buffer overflow");

		return(-1);

	}

	return(0);

}

#else

#define DEFINE_COPY_ROW(name, type)			\

void name(type *src, int src_w, type *dst, int dst_w)	\

{							\

	int i;						\

	int pos, inc;					\

	type pixel = 0;					\

							\

	pos = 0x10000;					\

	inc = (src_w << 16) / dst_w;			\

	for ( i=dst_w; i>0; --i ) {			\

		while ( pos >= 0x10000L ) {		\

			pixel = *src++;			\

			pos -= 0x10000L;		\

		}					\

		*dst++ = pixel;				\

		pos += inc;				\

	}						\

}

DEFINE_COPY_ROW(copy_row1, Uint8)

DEFINE_COPY_ROW(copy_row2, Uint16)

DEFINE_COPY_ROW(copy_row4, Uint32)

#endif /* USE_ASM_STRETCH */

/* The ASM code doesn't handle 24-bpp stretch blits */

void copy_row3(Uint8 *src, int src_w, Uint8 *dst, int dst_w)

{

	int i;

	int pos, inc;

	Uint8 pixel[3];

	pos = 0x10000;

	inc = (src_w << 16) / dst_w;

	for ( i=dst_w; i>0; --i ) {

		while ( pos >= 0x10000L ) {

			pixel[0] = *src++;

			pixel[1] = *src++;

			pixel[2] = *src++;

			pos -= 0x10000L;

		}

		*dst++ = pixel[0];

		*dst++ = pixel[1];

		*dst++ = pixel[2];

		pos += inc;

	}

}

/* Perform a stretch blit between two surfaces of the same format.

   NOTE:  This function is not safe to call from multiple threads!

*/

int SDL_SoftStretch(SDL_Surface *src, SDL_Rect *srcrect,

                    SDL_Surface *dst, SDL_Rect *dstrect)

{

	int pos, inc;

	int dst_width;

	int dst_maxrow;

	int src_row, dst_row;

	Uint8 *srcp = NULL;

	Uint8 *dstp;

	SDL_Rect full_src;

	SDL_Rect full_dst;

#if defined(USE_ASM_STRETCH) && defined(__GNUC__)

	int u1, u2;

#endif

	const int bpp = dst->format->BytesPerPixel;

	if ( src->format->BitsPerPixel != dst->format->BitsPerPixel ) {

		SDL_SetError("Only works with same format surfaces");

		return(-1);

	}

	/* Verify the blit rectangles */

	if ( srcrect ) {

		if ( (srcrect->x < 0) || (srcrect->y < 0) ||

		     ((srcrect->x+srcrect->w) > src->w) ||

		     ((srcrect->y+srcrect->h) > src->h) ) {

			SDL_SetError("Invalid source blit rectangle");

			return(-1);

		}

	} else {

		full_src.x = 0;

		full_src.y = 0;

		full_src.w = src->w;

		full_src.h = src->h;

		srcrect = &full_src;

	}

	if ( dstrect ) {

		if ( (dstrect->x < 0) || (dstrect->y < 0) ||

		     ((dstrect->x+dstrect->w) > dst->w) ||

		     ((dstrect->y+dstrect->h) > dst->h) ) {

			SDL_SetError("Invalid destination blit rectangle");

			return(-1);

		}

	} else {

		full_dst.x = 0;

		full_dst.y = 0;

		full_dst.w = dst->w;

		full_dst.h = dst->h;

		dstrect = &full_dst;

	}

	/* Set up the data... */

	pos = 0x10000;

	inc = (srcrect->h << 16) / dstrect->h;

	src_row = srcrect->y;

	dst_row = dstrect->y;

	dst_width = dstrect->w*bpp;

#ifdef USE_ASM_STRETCH

	/* Write the opcodes for this stretch */

	if ( (bpp != 3) &&

	     (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0) ) {

		return(-1);

	}

#endif

	/* Perform the stretch blit */

	for ( dst_maxrow = dst_row+dstrect->h; dst_row<dst_maxrow; ++dst_row ) {

		dstp = (Uint8 *)dst->pixels + (dst_row*dst->pitch)

		                            + (dstrect->x*bpp);

		while ( pos >= 0x10000L ) {

			srcp = (Uint8 *)src->pixels + (src_row*src->pitch)

			                            + (srcrect->x*bpp);

			++src_row;

			pos -= 0x10000L;

		}

#ifdef USE_ASM_STRETCH

		switch (bpp) {

		    case 3:

			copy_row3(srcp, srcrect->w, dstp, dstrect->w);

			break;

		    default:

#ifdef __GNUC__

			__asm__ __volatile__ ("

				call _copy_row

			"

			: "=&D" (u1), "=&S" (u2)

			: "0" (dstp), "1" (srcp)

			: "memory" );

#else

#ifdef WIN32

		{ void *code = &copy_row;

			__asm {

				push edi

				push esi

				mov edi, dstp

				mov esi, srcp

				call dword ptr code

				pop esi

				pop edi

			}

		}

#else

#error Need inline assembly for this compiler

#endif

#endif /* __GNUC__ */

			break;

		}

#else

		switch (bpp) {

		    case 1:

			copy_row1(srcp, srcrect->w, dstp, dstrect->w);

			break;

		    case 2:

			copy_row2((Uint16 *)srcp, srcrect->w,

			          (Uint16 *)dstp, dstrect->w);

			break;

		    case 3:

			copy_row3(srcp, srcrect->w, dstp, dstrect->w);

			break;

		    case 4:

			copy_row4((Uint32 *)srcp, srcrect->w,

			          (Uint32 *)dstp, dstrect->w);

			break;

		}

#endif

		pos += inc;

	}

	return(0);

}