src/video/SDL_stretch.c
author Ryan C. Gordon <icculus@icculus.org>
Tue, 01 Nov 2005 04:14:24 +0000
changeset 1164 10b3fb28c86b
parent 894 1d1a823904d8
child 1228 f4a3a4129d04
permissions -rw-r--r--
Date: Mon, 31 Oct 2005 14:23:34 +0100
From: Thomas Omilian <paccy@arcor.de>
To: sdl@libsdl.org
Subject: [SDL] SDL_SoftStretch() fixed!

Ok, after debugging the night I found the error:

in video/SDL_stretch.c in Line 81

/* 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);
}

the second comparison should be (dst_w == last dst_w).
Perhaps someone could apply it to the source...

Regards,
Thomas Omilian
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2004 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Library General Public
     7     License as published by the Free Software Foundation; either
     8     version 2 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Library General Public License for more details.
    14 
    15     You should have received a copy of the GNU Library General Public
    16     License along with this library; if not, write to the Free
    17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 
    23 #ifdef SAVE_RCSID
    24 static char rcsid =
    25  "@(#) $Id$";
    26 #endif
    27 
    28 /* This a stretch blit implementation based on ideas given to me by
    29    Tomasz Cejner - thanks! :)
    30 
    31    April 27, 2000 - Sam Lantinga
    32 */
    33 
    34 #include "SDL_error.h"
    35 #include "SDL_video.h"
    36 #include "SDL_blit.h"
    37 
    38 /* This isn't ready for general consumption yet - it should be folded
    39    into the general blitting mechanism.
    40 */
    41 
    42 #if (defined(WIN32) && !defined(_M_ALPHA) && !defined(_WIN32_WCE) && \
    43      !defined(__WATCOMC__) && !defined(__LCC__) && !defined(__FREEBCC__)) || \
    44     (defined(i386) && defined(__GNUC__) && defined(USE_ASMBLIT))
    45 #define USE_ASM_STRETCH
    46 #endif
    47 
    48 #ifdef USE_ASM_STRETCH
    49 
    50 #if defined(WIN32) || defined(i386)
    51 #define PREFIX16	0x66
    52 #define STORE_BYTE	0xAA
    53 #define STORE_WORD	0xAB
    54 #define LOAD_BYTE	0xAC
    55 #define LOAD_WORD	0xAD
    56 #define RETURN		0xC3
    57 #else
    58 #error Need assembly opcodes for this architecture
    59 #endif
    60 
    61 #if defined(__ELF__) && defined(__GNUC__)
    62 extern unsigned char _copy_row[4096] __attribute__ ((alias ("copy_row")));
    63 #endif
    64 static unsigned char copy_row[4096];
    65 
    66 static int generate_rowbytes(int src_w, int dst_w, int bpp)
    67 {
    68 	static struct {
    69 		int bpp;
    70 		int src_w;
    71 		int dst_w;
    72 	} last;
    73 
    74 	int i;
    75 	int pos, inc;
    76 	unsigned char *eip;
    77 	unsigned char load, store;
    78 
    79 	/* See if we need to regenerate the copy buffer */
    80 	if ( (src_w == last.src_w) &&
    81 	     (dst_w == last.dst_w) && (bpp == last.bpp) ) {
    82 		return(0);
    83 	}
    84 	last.bpp = bpp;
    85 	last.src_w = src_w;
    86 	last.dst_w = dst_w;
    87 
    88 	switch (bpp) {
    89 	    case 1:
    90 		load = LOAD_BYTE;
    91 		store = STORE_BYTE;
    92 		break;
    93 	    case 2:
    94 	    case 4:
    95 		load = LOAD_WORD;
    96 		store = STORE_WORD;
    97 		break;
    98 	    default:
    99 		SDL_SetError("ASM stretch of %d bytes isn't supported\n", bpp);
   100 		return(-1);
   101 	}
   102 	pos = 0x10000;
   103 	inc = (src_w << 16) / dst_w;
   104 	eip = copy_row;
   105 	for ( i=0; i<dst_w; ++i ) {
   106 		while ( pos >= 0x10000L ) {
   107 			if ( bpp == 2 ) {
   108 				*eip++ = PREFIX16;
   109 			}
   110 			*eip++ = load;
   111 			pos -= 0x10000L;
   112 		}
   113 		if ( bpp == 2 ) {
   114 			*eip++ = PREFIX16;
   115 		}
   116 		*eip++ = store;
   117 		pos += inc;
   118 	}
   119 	*eip++ = RETURN;
   120 
   121 	/* Verify that we didn't overflow (too late) */
   122 	if ( eip > (copy_row+sizeof(copy_row)) ) {
   123 		SDL_SetError("Copy buffer overflow");
   124 		return(-1);
   125 	}
   126 	return(0);
   127 }
   128 
   129 #else
   130 
   131 #define DEFINE_COPY_ROW(name, type)			\
   132 void name(type *src, int src_w, type *dst, int dst_w)	\
   133 {							\
   134 	int i;						\
   135 	int pos, inc;					\
   136 	type pixel = 0;					\
   137 							\
   138 	pos = 0x10000;					\
   139 	inc = (src_w << 16) / dst_w;			\
   140 	for ( i=dst_w; i>0; --i ) {			\
   141 		while ( pos >= 0x10000L ) {		\
   142 			pixel = *src++;			\
   143 			pos -= 0x10000L;		\
   144 		}					\
   145 		*dst++ = pixel;				\
   146 		pos += inc;				\
   147 	}						\
   148 }
   149 DEFINE_COPY_ROW(copy_row1, Uint8)
   150 DEFINE_COPY_ROW(copy_row2, Uint16)
   151 DEFINE_COPY_ROW(copy_row4, Uint32)
   152 
   153 #endif /* USE_ASM_STRETCH */
   154 
   155 /* The ASM code doesn't handle 24-bpp stretch blits */
   156 void copy_row3(Uint8 *src, int src_w, Uint8 *dst, int dst_w)
   157 {
   158 	int i;
   159 	int pos, inc;
   160 	Uint8 pixel[3];
   161 
   162 	pos = 0x10000;
   163 	inc = (src_w << 16) / dst_w;
   164 	for ( i=dst_w; i>0; --i ) {
   165 		while ( pos >= 0x10000L ) {
   166 			pixel[0] = *src++;
   167 			pixel[1] = *src++;
   168 			pixel[2] = *src++;
   169 			pos -= 0x10000L;
   170 		}
   171 		*dst++ = pixel[0];
   172 		*dst++ = pixel[1];
   173 		*dst++ = pixel[2];
   174 		pos += inc;
   175 	}
   176 }
   177 
   178 /* Perform a stretch blit between two surfaces of the same format.
   179    NOTE:  This function is not safe to call from multiple threads!
   180 */
   181 int SDL_SoftStretch(SDL_Surface *src, SDL_Rect *srcrect,
   182                     SDL_Surface *dst, SDL_Rect *dstrect)
   183 {
   184 	int src_locked;
   185 	int dst_locked;
   186 	int pos, inc;
   187 	int dst_width;
   188 	int dst_maxrow;
   189 	int src_row, dst_row;
   190 	Uint8 *srcp = NULL;
   191 	Uint8 *dstp;
   192 	SDL_Rect full_src;
   193 	SDL_Rect full_dst;
   194 #if defined(USE_ASM_STRETCH) && defined(__GNUC__)
   195 	int u1, u2;
   196 #endif
   197 	const int bpp = dst->format->BytesPerPixel;
   198 
   199 	if ( src->format->BitsPerPixel != dst->format->BitsPerPixel ) {
   200 		SDL_SetError("Only works with same format surfaces");
   201 		return(-1);
   202 	}
   203 
   204 	/* Verify the blit rectangles */
   205 	if ( srcrect ) {
   206 		if ( (srcrect->x < 0) || (srcrect->y < 0) ||
   207 		     ((srcrect->x+srcrect->w) > src->w) ||
   208 		     ((srcrect->y+srcrect->h) > src->h) ) {
   209 			SDL_SetError("Invalid source blit rectangle");
   210 			return(-1);
   211 		}
   212 	} else {
   213 		full_src.x = 0;
   214 		full_src.y = 0;
   215 		full_src.w = src->w;
   216 		full_src.h = src->h;
   217 		srcrect = &full_src;
   218 	}
   219 	if ( dstrect ) {
   220 		if ( (dstrect->x < 0) || (dstrect->y < 0) ||
   221 		     ((dstrect->x+dstrect->w) > dst->w) ||
   222 		     ((dstrect->y+dstrect->h) > dst->h) ) {
   223 			SDL_SetError("Invalid destination blit rectangle");
   224 			return(-1);
   225 		}
   226 	} else {
   227 		full_dst.x = 0;
   228 		full_dst.y = 0;
   229 		full_dst.w = dst->w;
   230 		full_dst.h = dst->h;
   231 		dstrect = &full_dst;
   232 	}
   233 
   234 	/* Lock the destination if it's in hardware */
   235 	dst_locked = 0;
   236 	if ( SDL_MUSTLOCK(dst) ) {
   237 		if ( SDL_LockSurface(dst) < 0 ) {
   238 			SDL_SetError("Unable to lock destination surface");
   239 			return(-1);
   240 		}
   241 		dst_locked = 1;
   242 	}
   243 	/* Lock the source if it's in hardware */
   244 	src_locked = 0;
   245 	if ( SDL_MUSTLOCK(src) ) {
   246 		if ( SDL_LockSurface(src) < 0 ) {
   247 			if ( dst_locked ) {
   248 				SDL_UnlockSurface(dst);
   249 			}
   250 			SDL_SetError("Unable to lock source surface");
   251 			return(-1);
   252 		}
   253 		src_locked = 1;
   254 	}
   255 
   256 	/* Set up the data... */
   257 	pos = 0x10000;
   258 	inc = (srcrect->h << 16) / dstrect->h;
   259 	src_row = srcrect->y;
   260 	dst_row = dstrect->y;
   261 	dst_width = dstrect->w*bpp;
   262 
   263 #ifdef USE_ASM_STRETCH
   264 	/* Write the opcodes for this stretch */
   265 	if ( (bpp != 3) &&
   266 	     (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0) ) {
   267 		return(-1);
   268 	}
   269 #endif
   270 
   271 	/* Perform the stretch blit */
   272 	for ( dst_maxrow = dst_row+dstrect->h; dst_row<dst_maxrow; ++dst_row ) {
   273 		dstp = (Uint8 *)dst->pixels + (dst_row*dst->pitch)
   274 		                            + (dstrect->x*bpp);
   275 		while ( pos >= 0x10000L ) {
   276 			srcp = (Uint8 *)src->pixels + (src_row*src->pitch)
   277 			                            + (srcrect->x*bpp);
   278 			++src_row;
   279 			pos -= 0x10000L;
   280 		}
   281 #ifdef USE_ASM_STRETCH
   282 		switch (bpp) {
   283 		    case 3:
   284 			copy_row3(srcp, srcrect->w, dstp, dstrect->w);
   285 			break;
   286 		    default:
   287 #ifdef __GNUC__
   288 			__asm__ __volatile__ (
   289 			"call _copy_row"
   290 			: "=&D" (u1), "=&S" (u2)
   291 			: "0" (dstp), "1" (srcp)
   292 			: "memory" );
   293 #else
   294 #ifdef WIN32
   295 		{ void *code = &copy_row;
   296 			__asm {
   297 				push edi
   298 				push esi
   299 	
   300 				mov edi, dstp
   301 				mov esi, srcp
   302 				call dword ptr code
   303 
   304 				pop esi
   305 				pop edi
   306 			}
   307 		}
   308 #else
   309 #error Need inline assembly for this compiler
   310 #endif
   311 #endif /* __GNUC__ */
   312 			break;
   313 		}
   314 #else
   315 		switch (bpp) {
   316 		    case 1:
   317 			copy_row1(srcp, srcrect->w, dstp, dstrect->w);
   318 			break;
   319 		    case 2:
   320 			copy_row2((Uint16 *)srcp, srcrect->w,
   321 			          (Uint16 *)dstp, dstrect->w);
   322 			break;
   323 		    case 3:
   324 			copy_row3(srcp, srcrect->w, dstp, dstrect->w);
   325 			break;
   326 		    case 4:
   327 			copy_row4((Uint32 *)srcp, srcrect->w,
   328 			          (Uint32 *)dstp, dstrect->w);
   329 			break;
   330 		}
   331 #endif
   332 		pos += inc;
   333 	}
   334 
   335 	/* We need to unlock the surfaces if they're locked */
   336 	if ( dst_locked ) {
   337 		SDL_UnlockSurface(dst);
   338 	}
   339 	if ( src_locked ) {
   340 		SDL_UnlockSurface(src);
   341 	}
   342 	return(0);
   343 }
   344