/*

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@libsdl.org

*/

#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(__WATCOMC__) && !defined(__LCC__) && !defined(__FREEBCC__)) || \

(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);

}