/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

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

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 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

    Lesser General Public License for more details.

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

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

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#include "SDL_config.h"

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

   Tomasz Cejner - thanks! :)

   April 27, 2000 - Sam Lantinga

*/

#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(_MFC_VER) && defined(_M_IX86)/* && !defined(_WIN32_WCE) still needed? */) || \

     defined(__WATCOMC__) || \

     (defined(__GNUC__) && defined(__i386__))) && SDL_ASSEMBLY_ROUTINES

#define USE_ASM_STRETCH

#endif

#ifdef USE_ASM_STRETCH

#ifdef HAVE_MPROTECT

#include <sys/types.h>

#include <sys/mman.h>

#endif

#ifdef __GNUC__

#define PAGE_ALIGNED __attribute__((__aligned__(4096)))

#else

#define PAGE_ALIGNED

#endif

#if defined(_M_IX86) || 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

static unsigned char copy_row[4096] PAGE_ALIGNED;

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

{

	static struct {

		int bpp;

		int src_w;

		int dst_w;

		int status;

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

		return(last.status);

	}

	last.bpp = bpp;

	last.src_w = src_w;

	last.dst_w = dst_w;

	last.status = -1;

	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);

	}

#ifdef HAVE_MPROTECT

	/* Make the code executable */

	if ( mprotect(copy_row, sizeof(copy_row), PROT_READ|PROT_WRITE|PROT_EXEC) < 0 ) {

		SDL_SetError("Couldn't make copy buffer executable");

		return(-1);

	}

#endif

	last.status = 0;

	return(0);

}

#endif /* USE_ASM_STRETCH */

#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)

/* 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] = { 0, 0, 0 };

	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 src_locked;

	int dst_locked;

	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;

#ifdef USE_ASM_STRETCH

	SDL_bool use_asm = SDL_TRUE;

#ifdef __GNUC__

	int u1, u2;

#endif

#endif /* USE_ASM_STRETCH */

	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;

	}

	/* Lock the destination if it's in hardware */

	dst_locked = 0;

	if ( SDL_MUSTLOCK(dst) ) {

		if ( SDL_LockSurface(dst) < 0 ) {

			SDL_SetError("Unable to lock destination surface");

			return(-1);

		}

		dst_locked = 1;

	}

	/* Lock the source if it's in hardware */

	src_locked = 0;

	if ( SDL_MUSTLOCK(src) ) {

		if ( SDL_LockSurface(src) < 0 ) {

			if ( dst_locked ) {

				SDL_UnlockSurface(dst);

			}

			SDL_SetError("Unable to lock source surface");

			return(-1);

		}

		src_locked = 1;

	}

	/* 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) ) {

		use_asm = SDL_FALSE;

	}

#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

		if (use_asm) {

#ifdef __GNUC__

			__asm__ __volatile__ (

			"call *%4"

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

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

			: "memory" );

#elif defined(_MSC_VER) || defined(__WATCOMC__)

		{ 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

		} else

#endif

		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;

		}

		pos += inc;

	}

	/* We need to unlock the surfaces if they're locked */

	if ( dst_locked ) {

		SDL_UnlockSurface(dst);

	}

	if ( src_locked ) {

		SDL_UnlockSurface(src);

	}

	return(0);

}