src/video/SDL_stretch.c
changeset 0 74212992fb08
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     1 /*
       
     2     SDL - Simple DirectMedia Layer
       
     3     Copyright (C) 1997, 1998, 1999, 2000, 2001  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@devolution.com
       
    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(i386) && defined(__GNUC__) && defined(USE_ASMBLIT)
       
    44 #define USE_ASM_STRETCH
       
    45 #endif
       
    46 
       
    47 #ifdef USE_ASM_STRETCH
       
    48 
       
    49 #if defined(WIN32) || defined(i386)
       
    50 #define PREFIX16	0x66
       
    51 #define STORE_BYTE	0xAA
       
    52 #define STORE_WORD	0xAB
       
    53 #define LOAD_BYTE	0xAC
       
    54 #define LOAD_WORD	0xAD
       
    55 #define RETURN		0xC3
       
    56 #else
       
    57 #error Need assembly opcodes for this architecture
       
    58 #endif
       
    59 
       
    60 #if defined(__ELF__) && defined(__GNUC__)
       
    61 extern unsigned char _copy_row[4096] __attribute__ ((alias ("copy_row")));
       
    62 #endif
       
    63 static unsigned char copy_row[4096];
       
    64 
       
    65 static int generate_rowbytes(int src_w, int dst_w, int bpp)
       
    66 {
       
    67 	static struct {
       
    68 		int bpp;
       
    69 		int src_w;
       
    70 		int dst_w;
       
    71 	} last;
       
    72 
       
    73 	int i;
       
    74 	int pos, inc;
       
    75 	unsigned char *eip;
       
    76 	unsigned char load, store;
       
    77 
       
    78 	/* See if we need to regenerate the copy buffer */
       
    79 	if ( (src_w == last.src_w) &&
       
    80 	     (dst_w == last.src_w) && (bpp == last.bpp) ) {
       
    81 		return(0);
       
    82 	}
       
    83 	last.bpp = bpp;
       
    84 	last.src_w = src_w;
       
    85 	last.dst_w = dst_w;
       
    86 
       
    87 	switch (bpp) {
       
    88 	    case 1:
       
    89 		load = LOAD_BYTE;
       
    90 		store = STORE_BYTE;
       
    91 		break;
       
    92 	    case 2:
       
    93 	    case 4:
       
    94 		load = LOAD_WORD;
       
    95 		store = STORE_WORD;
       
    96 		break;
       
    97 	    default:
       
    98 		SDL_SetError("ASM stretch of %d bytes isn't supported\n", bpp);
       
    99 		return(-1);
       
   100 	}
       
   101 	pos = 0x10000;
       
   102 	inc = (src_w << 16) / dst_w;
       
   103 	eip = copy_row;
       
   104 	for ( i=0; i<dst_w; ++i ) {
       
   105 		while ( pos >= 0x10000L ) {
       
   106 			if ( bpp == 2 ) {
       
   107 				*eip++ = PREFIX16;
       
   108 			}
       
   109 			*eip++ = load;
       
   110 			pos -= 0x10000L;
       
   111 		}
       
   112 		if ( bpp == 2 ) {
       
   113 			*eip++ = PREFIX16;
       
   114 		}
       
   115 		*eip++ = store;
       
   116 		pos += inc;
       
   117 	}
       
   118 	*eip++ = RETURN;
       
   119 
       
   120 	/* Verify that we didn't overflow (too late) */
       
   121 	if ( eip > (copy_row+sizeof(copy_row)) ) {
       
   122 		SDL_SetError("Copy buffer overflow");
       
   123 		return(-1);
       
   124 	}
       
   125 	return(0);
       
   126 }
       
   127 
       
   128 #else
       
   129 
       
   130 #define DEFINE_COPY_ROW(name, type)			\
       
   131 void name(type *src, int src_w, type *dst, int dst_w)	\
       
   132 {							\
       
   133 	int i;						\
       
   134 	int pos, inc;					\
       
   135 	type pixel = 0;					\
       
   136 							\
       
   137 	pos = 0x10000;					\
       
   138 	inc = (src_w << 16) / dst_w;			\
       
   139 	for ( i=dst_w; i>0; --i ) {			\
       
   140 		while ( pos >= 0x10000L ) {		\
       
   141 			pixel = *src++;			\
       
   142 			pos -= 0x10000L;		\
       
   143 		}					\
       
   144 		*dst++ = pixel;				\
       
   145 		pos += inc;				\
       
   146 	}						\
       
   147 }
       
   148 DEFINE_COPY_ROW(copy_row1, Uint8)
       
   149 DEFINE_COPY_ROW(copy_row2, Uint16)
       
   150 DEFINE_COPY_ROW(copy_row4, Uint32)
       
   151 
       
   152 #endif /* USE_ASM_STRETCH */
       
   153 
       
   154 /* The ASM code doesn't handle 24-bpp stretch blits */
       
   155 void copy_row3(Uint8 *src, int src_w, Uint8 *dst, int dst_w)
       
   156 {
       
   157 	int i;
       
   158 	int pos, inc;
       
   159 	Uint8 pixel[3];
       
   160 
       
   161 	pos = 0x10000;
       
   162 	inc = (src_w << 16) / dst_w;
       
   163 	for ( i=dst_w; i>0; --i ) {
       
   164 		while ( pos >= 0x10000L ) {
       
   165 			pixel[0] = *src++;
       
   166 			pixel[1] = *src++;
       
   167 			pixel[2] = *src++;
       
   168 			pos -= 0x10000L;
       
   169 		}
       
   170 		*dst++ = pixel[0];
       
   171 		*dst++ = pixel[1];
       
   172 		*dst++ = pixel[2];
       
   173 		pos += inc;
       
   174 	}
       
   175 }
       
   176 
       
   177 /* Perform a stretch blit between two surfaces of the same format.
       
   178    NOTE:  This function is not safe to call from multiple threads!
       
   179 */
       
   180 int SDL_SoftStretch(SDL_Surface *src, SDL_Rect *srcrect,
       
   181                     SDL_Surface *dst, SDL_Rect *dstrect)
       
   182 {
       
   183 	int pos, inc;
       
   184 	int dst_width;
       
   185 	int dst_maxrow;
       
   186 	int src_row, dst_row;
       
   187 	Uint8 *srcp = NULL;
       
   188 	Uint8 *dstp;
       
   189 	SDL_Rect full_src;
       
   190 	SDL_Rect full_dst;
       
   191 #if defined(USE_ASM_STRETCH) && defined(__GNUC__)
       
   192 	int u1, u2;
       
   193 #endif
       
   194 	const int bpp = dst->format->BytesPerPixel;
       
   195 
       
   196 	if ( src->format->BitsPerPixel != dst->format->BitsPerPixel ) {
       
   197 		SDL_SetError("Only works with same format surfaces");
       
   198 		return(-1);
       
   199 	}
       
   200 
       
   201 	/* Verify the blit rectangles */
       
   202 	if ( srcrect ) {
       
   203 		if ( (srcrect->x < 0) || (srcrect->y < 0) ||
       
   204 		     ((srcrect->x+srcrect->w) > src->w) ||
       
   205 		     ((srcrect->y+srcrect->h) > src->h) ) {
       
   206 			SDL_SetError("Invalid source blit rectangle");
       
   207 			return(-1);
       
   208 		}
       
   209 	} else {
       
   210 		full_src.x = 0;
       
   211 		full_src.y = 0;
       
   212 		full_src.w = src->w;
       
   213 		full_src.h = src->h;
       
   214 		srcrect = &full_src;
       
   215 	}
       
   216 	if ( dstrect ) {
       
   217 		if ( (dstrect->x < 0) || (dstrect->y < 0) ||
       
   218 		     ((dstrect->x+dstrect->w) > dst->w) ||
       
   219 		     ((dstrect->y+dstrect->h) > dst->h) ) {
       
   220 			SDL_SetError("Invalid destination blit rectangle");
       
   221 			return(-1);
       
   222 		}
       
   223 	} else {
       
   224 		full_dst.x = 0;
       
   225 		full_dst.y = 0;
       
   226 		full_dst.w = dst->w;
       
   227 		full_dst.h = dst->h;
       
   228 		dstrect = &full_dst;
       
   229 	}
       
   230 
       
   231 	/* Set up the data... */
       
   232 	pos = 0x10000;
       
   233 	inc = (srcrect->h << 16) / dstrect->h;
       
   234 	src_row = srcrect->y;
       
   235 	dst_row = dstrect->y;
       
   236 	dst_width = dstrect->w*bpp;
       
   237 
       
   238 #ifdef USE_ASM_STRETCH
       
   239 	/* Write the opcodes for this stretch */
       
   240 	if ( (bpp != 3) &&
       
   241 	     (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0) ) {
       
   242 		return(-1);
       
   243 	}
       
   244 #endif
       
   245 
       
   246 	/* Perform the stretch blit */
       
   247 	for ( dst_maxrow = dst_row+dstrect->h; dst_row<dst_maxrow; ++dst_row ) {
       
   248 		dstp = (Uint8 *)dst->pixels + (dst_row*dst->pitch)
       
   249 		                            + (dstrect->x*bpp);
       
   250 		while ( pos >= 0x10000L ) {
       
   251 			srcp = (Uint8 *)src->pixels + (src_row*src->pitch)
       
   252 			                            + (srcrect->x*bpp);
       
   253 			++src_row;
       
   254 			pos -= 0x10000L;
       
   255 		}
       
   256 #ifdef USE_ASM_STRETCH
       
   257 		switch (bpp) {
       
   258 		    case 3:
       
   259 			copy_row3(srcp, srcrect->w, dstp, dstrect->w);
       
   260 			break;
       
   261 		    default:
       
   262 #ifdef __GNUC__
       
   263 			__asm__ __volatile__ ("
       
   264 				call _copy_row
       
   265 			"
       
   266 			: "=&D" (u1), "=&S" (u2)
       
   267 			: "0" (dstp), "1" (srcp)
       
   268 			: "memory" );
       
   269 #else
       
   270 #ifdef WIN32
       
   271 		{ void *code = &copy_row;
       
   272 			__asm {
       
   273 				push edi
       
   274 				push esi
       
   275 	
       
   276 				mov edi, dstp
       
   277 				mov esi, srcp
       
   278 				call dword ptr code
       
   279 
       
   280 				pop esi
       
   281 				pop edi
       
   282 			}
       
   283 		}
       
   284 #else
       
   285 #error Need inline assembly for this compiler
       
   286 #endif
       
   287 #endif /* __GNUC__ */
       
   288 			break;
       
   289 		}
       
   290 #else
       
   291 		switch (bpp) {
       
   292 		    case 1:
       
   293 			copy_row1(srcp, srcrect->w, dstp, dstrect->w);
       
   294 			break;
       
   295 		    case 2:
       
   296 			copy_row2((Uint16 *)srcp, srcrect->w,
       
   297 			          (Uint16 *)dstp, dstrect->w);
       
   298 			break;
       
   299 		    case 3:
       
   300 			copy_row3(srcp, srcrect->w, dstp, dstrect->w);
       
   301 			break;
       
   302 		    case 4:
       
   303 			copy_row4((Uint32 *)srcp, srcrect->w,
       
   304 			          (Uint32 *)dstp, dstrect->w);
       
   305 			break;
       
   306 		}
       
   307 #endif
       
   308 		pos += inc;
       
   309 	}
       
   310 	return(0);
       
   311 }
       
   312