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SDL_stretch.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2009 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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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
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Lesser General Public License for more details.
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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
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Sam Lantinga
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slouken@libsdl.org
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*/
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#include "SDL_config.h"
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/* 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.
*/
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#if ((defined(_MFC_VER) && defined(_M_IX86)/* && !defined(_WIN32_WCE) still needed? */) || \
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defined(__WATCOMC__) || \
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(defined(__GNUC__) && defined(__i386__))) && SDL_ASSEMBLY_ROUTINES
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/* There's a bug with gcc 4.4.1 and -O2 where srcp doesn't get the correct
* value after the first scanline. FIXME? */
/*#define USE_ASM_STRETCH*/
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#endif
#ifdef USE_ASM_STRETCH
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#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
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#if defined(_M_IX86) || defined(i386)
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#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
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static unsigned char copy_row[4096] PAGE_ALIGNED;
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static int
generate_rowbytes(int src_w, int dst_w, int bpp)
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static struct
{
int bpp;
int src_w;
int dst_w;
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int status;
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} 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)) {
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return (last.status);
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}
last.bpp = bpp;
last.src_w = src_w;
last.dst_w = dst_w;
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last.status = -1;
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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);
}
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#ifdef HAVE_MPROTECT
/* Make the code writeable */
if (mprotect(copy_row, sizeof(copy_row), PROT_READ | PROT_WRITE) < 0) {
SDL_SetError("Couldn't make copy buffer writeable");
return (-1);
}
#endif
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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;
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/* Verify that we didn't overflow (too late!!!) */
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if (eip > (copy_row + sizeof(copy_row))) {
SDL_SetError("Copy buffer overflow");
return (-1);
}
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#ifdef HAVE_MPROTECT
/* Make the code executable but not writeable */
if (mprotect(copy_row, sizeof(copy_row), PROT_READ | PROT_EXEC) < 0) {
SDL_SetError("Couldn't make copy buffer executable");
return (-1);
}
#endif
last.status = 0;
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}
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#endif /* USE_ASM_STRETCH */
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#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; \
} \
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}
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/* *INDENT-OFF* */
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DEFINE_COPY_ROW(copy_row1, Uint8)
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DEFINE_COPY_ROW(copy_row2, Uint16)
DEFINE_COPY_ROW(copy_row4, Uint32)
/* *INDENT-ON* */
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/* The ASM code doesn't handle 24-bpp stretch blits */
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void
copy_row3(Uint8 * src, int src_w, Uint8 * dst, int dst_w)
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{
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int i;
int pos, inc;
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Uint8 pixel[3] = { 0, 0, 0 };
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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;
}
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}
/* Perform a stretch blit between two surfaces of the same format.
NOTE: This function is not safe to call from multiple threads!
*/
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SDL_SoftStretch(SDL_Surface * src, const SDL_Rect * srcrect,
SDL_Surface * dst, const SDL_Rect * dstrect)
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{
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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;
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#ifdef USE_ASM_STRETCH
SDL_bool use_asm = SDL_TRUE;
#ifdef __GNUC__
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#endif
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#endif /* USE_ASM_STRETCH */
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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;
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#ifdef USE_ASM_STRETCH
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/* Write the opcodes for this stretch */
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if ((bpp == 3) || (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0)) {
use_asm = SDL_FALSE;
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#endif
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/* 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;
}
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#ifdef USE_ASM_STRETCH
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if (use_asm) {
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#ifdef __GNUC__
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__asm__ __volatile__("call *%4":"=&D"(u1), "=&S"(u2)
:"0"(dstp), "1"(srcp), "r"(copy_row)
:"memory");
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#elif defined(_MSC_VER) || defined(__WATCOMC__)
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/* *INDENT-OFF* */
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{
void *code = copy_row;
__asm {
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push edi
push esi
mov edi, dstp
mov esi, srcp
call dword ptr code
pop esi
pop edi
}
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/* *INDENT-ON* */
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#else
#error Need inline assembly for this compiler
#endif
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#endif
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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;
}
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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);
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}
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/* vi: set ts=4 sw=4 expandtab: */