view src/video/SDL_stretch.c @ 4168:69bcba65c388 SDL-1.2

Fixed bug #526 Comment #1 From Simon Howard 2009-03-20 16:50:56 Hi, I'm the author of Chocolate Doom, one of the other source ports that James mentioned. This is a patch against the current SVN version of SDL 1.2 that fixes the bug. It has been tested and hopefully should be obviously correct from examining the changes. I'll give a brief explanation. When the palette is set with SDL_SetPalette, the IDirectDrawPalette_SetEntries DirectX function is invoked. However, when this happens, a WM_PALETTECHANGED message is sent to the window. A WM_PALETTECHANGED message can also be received if the palette is changed for some other reason, like if the system palette is changed. Therefore, the palette change handler (DX5_PaletteChanged) has code to deal with this case. It distinguishes "expected" palette changes (set with SDL_SetPalette) from "unexpected" palette changes using the colorchange_expected variable, which is set before calling IDirectDrawPalette_SetEntries. However, the code to set this variable is missing in the fullscreen code path. By setting this variable, the palette change is handled properly and the freezes go away.
author Sam Lantinga <slouken@libsdl.org>
date Mon, 13 Apr 2009 00:53:12 +0000
parents a1b03ba2fcd0
children 9b464226e541
line wrap: on
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 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);
}