src/video/SDL_stretch.c
author Sam Lantinga <slouken@libsdl.org>
Wed, 17 May 2006 15:08:46 +0000
changeset 1849 b5a4ac87b98c
parent 1442 e3242177fe4a
child 1895 c121d94672cb
child 4108 3feb94233f90
permissions -rw-r--r--
Fixed uninitialized variable warnings
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2006 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 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     Lesser General Public License for more details.
    14 
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 #include "SDL_config.h"
    23 
    24 /* This a stretch blit implementation based on ideas given to me by
    25    Tomasz Cejner - thanks! :)
    26 
    27    April 27, 2000 - Sam Lantinga
    28 */
    29 
    30 #include "SDL_video.h"
    31 #include "SDL_blit.h"
    32 
    33 /* This isn't ready for general consumption yet - it should be folded
    34    into the general blitting mechanism.
    35 */
    36 
    37 #if ((defined(_MFC_VER) && defined(_M_IX86)/* && !defined(_WIN32_WCE) still needed? */) || \
    38      defined(__WATCOMC__) || \
    39      (defined(__GNUC__) && defined(__i386__))) && SDL_ASSEMBLY_ROUTINES
    40 #define USE_ASM_STRETCH
    41 #endif
    42 
    43 #ifdef USE_ASM_STRETCH
    44 
    45 #if defined(_M_IX86) || defined(i386)
    46 #define PREFIX16	0x66
    47 #define STORE_BYTE	0xAA
    48 #define STORE_WORD	0xAB
    49 #define LOAD_BYTE	0xAC
    50 #define LOAD_WORD	0xAD
    51 #define RETURN		0xC3
    52 #else
    53 #error Need assembly opcodes for this architecture
    54 #endif
    55 
    56 static unsigned char copy_row[4096];
    57 
    58 static int generate_rowbytes(int src_w, int dst_w, int bpp)
    59 {
    60 	static struct {
    61 		int bpp;
    62 		int src_w;
    63 		int dst_w;
    64 	} last;
    65 
    66 	int i;
    67 	int pos, inc;
    68 	unsigned char *eip;
    69 	unsigned char load, store;
    70 
    71 	/* See if we need to regenerate the copy buffer */
    72 	if ( (src_w == last.src_w) &&
    73 	     (dst_w == last.dst_w) && (bpp == last.bpp) ) {
    74 		return(0);
    75 	}
    76 	last.bpp = bpp;
    77 	last.src_w = src_w;
    78 	last.dst_w = dst_w;
    79 
    80 	switch (bpp) {
    81 	    case 1:
    82 		load = LOAD_BYTE;
    83 		store = STORE_BYTE;
    84 		break;
    85 	    case 2:
    86 	    case 4:
    87 		load = LOAD_WORD;
    88 		store = STORE_WORD;
    89 		break;
    90 	    default:
    91 		SDL_SetError("ASM stretch of %d bytes isn't supported\n", bpp);
    92 		return(-1);
    93 	}
    94 	pos = 0x10000;
    95 	inc = (src_w << 16) / dst_w;
    96 	eip = copy_row;
    97 	for ( i=0; i<dst_w; ++i ) {
    98 		while ( pos >= 0x10000L ) {
    99 			if ( bpp == 2 ) {
   100 				*eip++ = PREFIX16;
   101 			}
   102 			*eip++ = load;
   103 			pos -= 0x10000L;
   104 		}
   105 		if ( bpp == 2 ) {
   106 			*eip++ = PREFIX16;
   107 		}
   108 		*eip++ = store;
   109 		pos += inc;
   110 	}
   111 	*eip++ = RETURN;
   112 
   113 	/* Verify that we didn't overflow (too late) */
   114 	if ( eip > (copy_row+sizeof(copy_row)) ) {
   115 		SDL_SetError("Copy buffer overflow");
   116 		return(-1);
   117 	}
   118 	return(0);
   119 }
   120 
   121 #else
   122 
   123 #define DEFINE_COPY_ROW(name, type)			\
   124 void name(type *src, int src_w, type *dst, int dst_w)	\
   125 {							\
   126 	int i;						\
   127 	int pos, inc;					\
   128 	type pixel = 0;					\
   129 							\
   130 	pos = 0x10000;					\
   131 	inc = (src_w << 16) / dst_w;			\
   132 	for ( i=dst_w; i>0; --i ) {			\
   133 		while ( pos >= 0x10000L ) {		\
   134 			pixel = *src++;			\
   135 			pos -= 0x10000L;		\
   136 		}					\
   137 		*dst++ = pixel;				\
   138 		pos += inc;				\
   139 	}						\
   140 }
   141 DEFINE_COPY_ROW(copy_row1, Uint8)
   142 DEFINE_COPY_ROW(copy_row2, Uint16)
   143 DEFINE_COPY_ROW(copy_row4, Uint32)
   144 
   145 #endif /* USE_ASM_STRETCH */
   146 
   147 /* The ASM code doesn't handle 24-bpp stretch blits */
   148 void copy_row3(Uint8 *src, int src_w, Uint8 *dst, int dst_w)
   149 {
   150 	int i;
   151 	int pos, inc;
   152 	Uint8 pixel[3] = { 0, 0, 0 };
   153 
   154 	pos = 0x10000;
   155 	inc = (src_w << 16) / dst_w;
   156 	for ( i=dst_w; i>0; --i ) {
   157 		while ( pos >= 0x10000L ) {
   158 			pixel[0] = *src++;
   159 			pixel[1] = *src++;
   160 			pixel[2] = *src++;
   161 			pos -= 0x10000L;
   162 		}
   163 		*dst++ = pixel[0];
   164 		*dst++ = pixel[1];
   165 		*dst++ = pixel[2];
   166 		pos += inc;
   167 	}
   168 }
   169 
   170 /* Perform a stretch blit between two surfaces of the same format.
   171    NOTE:  This function is not safe to call from multiple threads!
   172 */
   173 int SDL_SoftStretch(SDL_Surface *src, SDL_Rect *srcrect,
   174                     SDL_Surface *dst, SDL_Rect *dstrect)
   175 {
   176 	int src_locked;
   177 	int dst_locked;
   178 	int pos, inc;
   179 	int dst_width;
   180 	int dst_maxrow;
   181 	int src_row, dst_row;
   182 	Uint8 *srcp = NULL;
   183 	Uint8 *dstp;
   184 	SDL_Rect full_src;
   185 	SDL_Rect full_dst;
   186 #if defined(USE_ASM_STRETCH) && defined(__GNUC__)
   187 	int u1, u2;
   188 #endif
   189 	const int bpp = dst->format->BytesPerPixel;
   190 
   191 	if ( src->format->BitsPerPixel != dst->format->BitsPerPixel ) {
   192 		SDL_SetError("Only works with same format surfaces");
   193 		return(-1);
   194 	}
   195 
   196 	/* Verify the blit rectangles */
   197 	if ( srcrect ) {
   198 		if ( (srcrect->x < 0) || (srcrect->y < 0) ||
   199 		     ((srcrect->x+srcrect->w) > src->w) ||
   200 		     ((srcrect->y+srcrect->h) > src->h) ) {
   201 			SDL_SetError("Invalid source blit rectangle");
   202 			return(-1);
   203 		}
   204 	} else {
   205 		full_src.x = 0;
   206 		full_src.y = 0;
   207 		full_src.w = src->w;
   208 		full_src.h = src->h;
   209 		srcrect = &full_src;
   210 	}
   211 	if ( dstrect ) {
   212 		if ( (dstrect->x < 0) || (dstrect->y < 0) ||
   213 		     ((dstrect->x+dstrect->w) > dst->w) ||
   214 		     ((dstrect->y+dstrect->h) > dst->h) ) {
   215 			SDL_SetError("Invalid destination blit rectangle");
   216 			return(-1);
   217 		}
   218 	} else {
   219 		full_dst.x = 0;
   220 		full_dst.y = 0;
   221 		full_dst.w = dst->w;
   222 		full_dst.h = dst->h;
   223 		dstrect = &full_dst;
   224 	}
   225 
   226 	/* Lock the destination if it's in hardware */
   227 	dst_locked = 0;
   228 	if ( SDL_MUSTLOCK(dst) ) {
   229 		if ( SDL_LockSurface(dst) < 0 ) {
   230 			SDL_SetError("Unable to lock destination surface");
   231 			return(-1);
   232 		}
   233 		dst_locked = 1;
   234 	}
   235 	/* Lock the source if it's in hardware */
   236 	src_locked = 0;
   237 	if ( SDL_MUSTLOCK(src) ) {
   238 		if ( SDL_LockSurface(src) < 0 ) {
   239 			if ( dst_locked ) {
   240 				SDL_UnlockSurface(dst);
   241 			}
   242 			SDL_SetError("Unable to lock source surface");
   243 			return(-1);
   244 		}
   245 		src_locked = 1;
   246 	}
   247 
   248 	/* Set up the data... */
   249 	pos = 0x10000;
   250 	inc = (srcrect->h << 16) / dstrect->h;
   251 	src_row = srcrect->y;
   252 	dst_row = dstrect->y;
   253 	dst_width = dstrect->w*bpp;
   254 
   255 #ifdef USE_ASM_STRETCH
   256 	/* Write the opcodes for this stretch */
   257 	if ( (bpp != 3) &&
   258 	     (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0) ) {
   259 		return(-1);
   260 	}
   261 #endif
   262 
   263 	/* Perform the stretch blit */
   264 	for ( dst_maxrow = dst_row+dstrect->h; dst_row<dst_maxrow; ++dst_row ) {
   265 		dstp = (Uint8 *)dst->pixels + (dst_row*dst->pitch)
   266 		                            + (dstrect->x*bpp);
   267 		while ( pos >= 0x10000L ) {
   268 			srcp = (Uint8 *)src->pixels + (src_row*src->pitch)
   269 			                            + (srcrect->x*bpp);
   270 			++src_row;
   271 			pos -= 0x10000L;
   272 		}
   273 #ifdef USE_ASM_STRETCH
   274 		switch (bpp) {
   275 		    case 3:
   276 			copy_row3(srcp, srcrect->w, dstp, dstrect->w);
   277 			break;
   278 		    default:
   279 #ifdef __GNUC__
   280 			__asm__ __volatile__ (
   281 			"call *%4"
   282 			: "=&D" (u1), "=&S" (u2)
   283 			: "0" (dstp), "1" (srcp), "r" (copy_row)
   284 			: "memory" );
   285 #elif defined(_MSC_VER) || defined(__WATCOMC__)
   286 		{ void *code = copy_row;
   287 			__asm {
   288 				push edi
   289 				push esi
   290 	
   291 				mov edi, dstp
   292 				mov esi, srcp
   293 				call dword ptr code
   294 
   295 				pop esi
   296 				pop edi
   297 			}
   298 		}
   299 #else
   300 #error Need inline assembly for this compiler
   301 #endif
   302 			break;
   303 		}
   304 #else
   305 		switch (bpp) {
   306 		    case 1:
   307 			copy_row1(srcp, srcrect->w, dstp, dstrect->w);
   308 			break;
   309 		    case 2:
   310 			copy_row2((Uint16 *)srcp, srcrect->w,
   311 			          (Uint16 *)dstp, dstrect->w);
   312 			break;
   313 		    case 3:
   314 			copy_row3(srcp, srcrect->w, dstp, dstrect->w);
   315 			break;
   316 		    case 4:
   317 			copy_row4((Uint32 *)srcp, srcrect->w,
   318 			          (Uint32 *)dstp, dstrect->w);
   319 			break;
   320 		}
   321 #endif
   322 		pos += inc;
   323 	}
   324 
   325 	/* We need to unlock the surfaces if they're locked */
   326 	if ( dst_locked ) {
   327 		SDL_UnlockSurface(dst);
   328 	}
   329 	if ( src_locked ) {
   330 		SDL_UnlockSurface(src);
   331 	}
   332 	return(0);
   333 }
   334