src/video/SDL_stretch.c
author Sam Lantinga <slouken@libsdl.org>
Sat, 29 Dec 2007 05:18:33 +0000
branchSDL-1.2
changeset 4109 cd2ab40f1219
parent 4108 3feb94233f90
child 4159 a1b03ba2fcd0
permissions -rw-r--r--
Made the mprotect() fix for SDL_SoftStretch() more general for hardened linux, etc.
     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 #ifdef HAVE_MPROTECT
    46 #include <sys/types.h>
    47 #include <sys/mman.h>
    48 #endif
    49 #ifdef __GNUC__
    50 #define PAGE_ALIGNED __attribute__((__aligned__(4096)))
    51 #else
    52 #define PAGE_ALIGNED
    53 #endif
    54 
    55 #if defined(_M_IX86) || defined(i386)
    56 #define PREFIX16	0x66
    57 #define STORE_BYTE	0xAA
    58 #define STORE_WORD	0xAB
    59 #define LOAD_BYTE	0xAC
    60 #define LOAD_WORD	0xAD
    61 #define RETURN		0xC3
    62 #else
    63 #error Need assembly opcodes for this architecture
    64 #endif
    65 
    66 static unsigned char copy_row[4096] PAGE_ALIGNED;
    67 
    68 static int generate_rowbytes(int src_w, int dst_w, int bpp)
    69 {
    70 	static struct {
    71 		int bpp;
    72 		int src_w;
    73 		int dst_w;
    74 		int status;
    75 	} last;
    76 
    77 	int i;
    78 	int pos, inc;
    79 	unsigned char *eip;
    80 	unsigned char load, store;
    81 
    82 	/* See if we need to regenerate the copy buffer */
    83 	if ( (src_w == last.src_w) &&
    84 	     (dst_w == last.dst_w) && (bpp == last.bpp) ) {
    85 		return(last.status);
    86 	}
    87 	last.bpp = bpp;
    88 	last.src_w = src_w;
    89 	last.dst_w = dst_w;
    90 	last.status = -1;
    91 
    92 	switch (bpp) {
    93 	    case 1:
    94 		load = LOAD_BYTE;
    95 		store = STORE_BYTE;
    96 		break;
    97 	    case 2:
    98 	    case 4:
    99 		load = LOAD_WORD;
   100 		store = STORE_WORD;
   101 		break;
   102 	    default:
   103 		SDL_SetError("ASM stretch of %d bytes isn't supported\n", bpp);
   104 		return(-1);
   105 	}
   106 	pos = 0x10000;
   107 	inc = (src_w << 16) / dst_w;
   108 	eip = copy_row;
   109 	for ( i=0; i<dst_w; ++i ) {
   110 		while ( pos >= 0x10000L ) {
   111 			if ( bpp == 2 ) {
   112 				*eip++ = PREFIX16;
   113 			}
   114 			*eip++ = load;
   115 			pos -= 0x10000L;
   116 		}
   117 		if ( bpp == 2 ) {
   118 			*eip++ = PREFIX16;
   119 		}
   120 		*eip++ = store;
   121 		pos += inc;
   122 	}
   123 	*eip++ = RETURN;
   124 
   125 	/* Verify that we didn't overflow (too late!!!) */
   126 	if ( eip > (copy_row+sizeof(copy_row)) ) {
   127 		SDL_SetError("Copy buffer overflow");
   128 		return(-1);
   129 	}
   130 #ifdef HAVE_MPROTECT
   131 	/* Make the code executable */
   132 	if ( mprotect(copy_row, sizeof(copy_row), PROT_READ|PROT_WRITE|PROT_EXEC) < 0 ) {
   133 		SDL_SetError("Couldn't make copy buffer executable");
   134 		return(-1);
   135 	}
   136 #endif
   137 	last.status = 0;
   138 	return(0);
   139 }
   140 
   141 #endif /* USE_ASM_STRETCH */
   142 
   143 #define DEFINE_COPY_ROW(name, type)			\
   144 void name(type *src, int src_w, type *dst, int dst_w)	\
   145 {							\
   146 	int i;						\
   147 	int pos, inc;					\
   148 	type pixel = 0;					\
   149 							\
   150 	pos = 0x10000;					\
   151 	inc = (src_w << 16) / dst_w;			\
   152 	for ( i=dst_w; i>0; --i ) {			\
   153 		while ( pos >= 0x10000L ) {		\
   154 			pixel = *src++;			\
   155 			pos -= 0x10000L;		\
   156 		}					\
   157 		*dst++ = pixel;				\
   158 		pos += inc;				\
   159 	}						\
   160 }
   161 DEFINE_COPY_ROW(copy_row1, Uint8)
   162 DEFINE_COPY_ROW(copy_row2, Uint16)
   163 DEFINE_COPY_ROW(copy_row4, Uint32)
   164 
   165 /* The ASM code doesn't handle 24-bpp stretch blits */
   166 void copy_row3(Uint8 *src, int src_w, Uint8 *dst, int dst_w)
   167 {
   168 	int i;
   169 	int pos, inc;
   170 	Uint8 pixel[3] = { 0, 0, 0 };
   171 
   172 	pos = 0x10000;
   173 	inc = (src_w << 16) / dst_w;
   174 	for ( i=dst_w; i>0; --i ) {
   175 		while ( pos >= 0x10000L ) {
   176 			pixel[0] = *src++;
   177 			pixel[1] = *src++;
   178 			pixel[2] = *src++;
   179 			pos -= 0x10000L;
   180 		}
   181 		*dst++ = pixel[0];
   182 		*dst++ = pixel[1];
   183 		*dst++ = pixel[2];
   184 		pos += inc;
   185 	}
   186 }
   187 
   188 /* Perform a stretch blit between two surfaces of the same format.
   189    NOTE:  This function is not safe to call from multiple threads!
   190 */
   191 int SDL_SoftStretch(SDL_Surface *src, SDL_Rect *srcrect,
   192                     SDL_Surface *dst, SDL_Rect *dstrect)
   193 {
   194 	int src_locked;
   195 	int dst_locked;
   196 	int pos, inc;
   197 	int dst_width;
   198 	int dst_maxrow;
   199 	int src_row, dst_row;
   200 	Uint8 *srcp = NULL;
   201 	Uint8 *dstp;
   202 	SDL_Rect full_src;
   203 	SDL_Rect full_dst;
   204 #ifdef USE_ASM_STRETCH
   205 	SDL_bool use_asm = SDL_TRUE;
   206 #ifdef __GNUC__
   207 	int u1, u2;
   208 #endif
   209 #endif /* USE_ASM_STRETCH */
   210 	const int bpp = dst->format->BytesPerPixel;
   211 
   212 	if ( src->format->BitsPerPixel != dst->format->BitsPerPixel ) {
   213 		SDL_SetError("Only works with same format surfaces");
   214 		return(-1);
   215 	}
   216 
   217 	/* Verify the blit rectangles */
   218 	if ( srcrect ) {
   219 		if ( (srcrect->x < 0) || (srcrect->y < 0) ||
   220 		     ((srcrect->x+srcrect->w) > src->w) ||
   221 		     ((srcrect->y+srcrect->h) > src->h) ) {
   222 			SDL_SetError("Invalid source blit rectangle");
   223 			return(-1);
   224 		}
   225 	} else {
   226 		full_src.x = 0;
   227 		full_src.y = 0;
   228 		full_src.w = src->w;
   229 		full_src.h = src->h;
   230 		srcrect = &full_src;
   231 	}
   232 	if ( dstrect ) {
   233 		if ( (dstrect->x < 0) || (dstrect->y < 0) ||
   234 		     ((dstrect->x+dstrect->w) > dst->w) ||
   235 		     ((dstrect->y+dstrect->h) > dst->h) ) {
   236 			SDL_SetError("Invalid destination blit rectangle");
   237 			return(-1);
   238 		}
   239 	} else {
   240 		full_dst.x = 0;
   241 		full_dst.y = 0;
   242 		full_dst.w = dst->w;
   243 		full_dst.h = dst->h;
   244 		dstrect = &full_dst;
   245 	}
   246 
   247 	/* Lock the destination if it's in hardware */
   248 	dst_locked = 0;
   249 	if ( SDL_MUSTLOCK(dst) ) {
   250 		if ( SDL_LockSurface(dst) < 0 ) {
   251 			SDL_SetError("Unable to lock destination surface");
   252 			return(-1);
   253 		}
   254 		dst_locked = 1;
   255 	}
   256 	/* Lock the source if it's in hardware */
   257 	src_locked = 0;
   258 	if ( SDL_MUSTLOCK(src) ) {
   259 		if ( SDL_LockSurface(src) < 0 ) {
   260 			if ( dst_locked ) {
   261 				SDL_UnlockSurface(dst);
   262 			}
   263 			SDL_SetError("Unable to lock source surface");
   264 			return(-1);
   265 		}
   266 		src_locked = 1;
   267 	}
   268 
   269 	/* Set up the data... */
   270 	pos = 0x10000;
   271 	inc = (srcrect->h << 16) / dstrect->h;
   272 	src_row = srcrect->y;
   273 	dst_row = dstrect->y;
   274 	dst_width = dstrect->w*bpp;
   275 
   276 #ifdef USE_ASM_STRETCH
   277 	/* Write the opcodes for this stretch */
   278 	if ( (bpp == 3) ||
   279 	     (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0) ) {
   280 		use_asm = SDL_FALSE;
   281 	}
   282 #endif
   283 
   284 	/* Perform the stretch blit */
   285 	for ( dst_maxrow = dst_row+dstrect->h; dst_row<dst_maxrow; ++dst_row ) {
   286 		dstp = (Uint8 *)dst->pixels + (dst_row*dst->pitch)
   287 		                            + (dstrect->x*bpp);
   288 		while ( pos >= 0x10000L ) {
   289 			srcp = (Uint8 *)src->pixels + (src_row*src->pitch)
   290 			                            + (srcrect->x*bpp);
   291 			++src_row;
   292 			pos -= 0x10000L;
   293 		}
   294 #ifdef USE_ASM_STRETCH
   295 		if (use_asm) {
   296 #ifdef __GNUC__
   297 			__asm__ __volatile__ (
   298 			"call *%4"
   299 			: "=&D" (u1), "=&S" (u2)
   300 			: "0" (dstp), "1" (srcp), "r" (copy_row)
   301 			: "memory" );
   302 #elif defined(_MSC_VER) || defined(__WATCOMC__)
   303 		{ void *code = copy_row;
   304 			__asm {
   305 				push edi
   306 				push esi
   307 	
   308 				mov edi, dstp
   309 				mov esi, srcp
   310 				call dword ptr code
   311 
   312 				pop esi
   313 				pop edi
   314 			}
   315 		}
   316 #else
   317 #error Need inline assembly for this compiler
   318 #endif
   319 		} else
   320 #endif
   321 		switch (bpp) {
   322 		    case 1:
   323 			copy_row1(srcp, srcrect->w, dstp, dstrect->w);
   324 			break;
   325 		    case 2:
   326 			copy_row2((Uint16 *)srcp, srcrect->w,
   327 			          (Uint16 *)dstp, dstrect->w);
   328 			break;
   329 		    case 3:
   330 			copy_row3(srcp, srcrect->w, dstp, dstrect->w);
   331 			break;
   332 		    case 4:
   333 			copy_row4((Uint32 *)srcp, srcrect->w,
   334 			          (Uint32 *)dstp, dstrect->w);
   335 			break;
   336 		}
   337 		pos += inc;
   338 	}
   339 
   340 	/* We need to unlock the surfaces if they're locked */
   341 	if ( dst_locked ) {
   342 		SDL_UnlockSurface(dst);
   343 	}
   344 	if ( src_locked ) {
   345 		SDL_UnlockSurface(src);
   346 	}
   347 	return(0);
   348 }
   349