SDL/SDL_stretch.c

   1 /*
   2     SDL - Simple DirectMedia Layer
   3     Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  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.src_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 pos, inc;
 185         int dst_width;
 186         int dst_maxrow;
 187         int src_row, dst_row;
 188         Uint8 *srcp = NULL;
 189         Uint8 *dstp;
 190         SDL_Rect full_src;
 191         SDL_Rect full_dst;
 192 #if defined(USE_ASM_STRETCH) && defined(__GNUC__)
 193         int u1, u2;
 194 #endif
 195         const int bpp = dst->format->BytesPerPixel;
 196
 197         if ( src->format->BitsPerPixel != dst->format->BitsPerPixel ) {
 198                 SDL_SetError("Only works with same format surfaces");
 199                 return(-1);
 200         }
 201
 202         /* Verify the blit rectangles */
 203         if ( srcrect ) {
 204                 if ( (srcrect->x < 0) || (srcrect->y < 0) ||
 205                      ((srcrect->x+srcrect->w) > src->w) ||
 206                      ((srcrect->y+srcrect->h) > src->h) ) {
 207                         SDL_SetError("Invalid source blit rectangle");
 208                         return(-1);
 209                 }
 210         } else {
 211                 full_src.x = 0;
 212                 full_src.y = 0;
 213                 full_src.w = src->w;
 214                 full_src.h = src->h;
 215                 srcrect = &full_src;
 216         }
 217         if ( dstrect ) {
 218                 if ( (dstrect->x < 0) || (dstrect->y < 0) ||
 219                      ((dstrect->x+dstrect->w) > dst->w) ||
 220                      ((dstrect->y+dstrect->h) > dst->h) ) {
 221                         SDL_SetError("Invalid destination blit rectangle");
 222                         return(-1);
 223                 }
 224         } else {
 225                 full_dst.x = 0;
 226                 full_dst.y = 0;
 227                 full_dst.w = dst->w;
 228                 full_dst.h = dst->h;
 229                 dstrect = &full_dst;
 230         }
 231
 232         /* Set up the data... */
 233         pos = 0x10000;
 234         inc = (srcrect->h << 16) / dstrect->h;
 235         src_row = srcrect->y;
 236         dst_row = dstrect->y;
 237         dst_width = dstrect->w*bpp;
 238
 239 #ifdef USE_ASM_STRETCH
 240         /* Write the opcodes for this stretch */
 241         if ( (bpp != 3) &&
 242              (generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0) ) {
 243                 return(-1);
 244         }
 245 #endif
 246
 247         /* Perform the stretch blit */
 248         for ( dst_maxrow = dst_row+dstrect->h; dst_row<dst_maxrow; ++dst_row ) {
 249                 dstp = (Uint8 *)dst->pixels + (dst_row*dst->pitch)
 250                                             + (dstrect->x*bpp);
 251                 while ( pos >= 0x10000L ) {
 252                         srcp = (Uint8 *)src->pixels + (src_row*src->pitch)
 253                                                     + (srcrect->x*bpp);
 254                         ++src_row;
 255                         pos -= 0x10000L;
 256                 }
 257 #ifdef USE_ASM_STRETCH
 258                 switch (bpp) {
 259                     case 3:
 260                         copy_row3(srcp, srcrect->w, dstp, dstrect->w);
 261                         break;
 262                     default:
 263 #ifdef __GNUC__
 264                         __asm__ __volatile__ (""
 265                                 "call _copy_row"
 266                         ""
 267                         : "=&D" (u1), "=&S" (u2)
 268                         : "0" (dstp), "1" (srcp)
 269                         : "memory" );
 270 #else
 271 #ifdef WIN32
 272                 { void *code = &copy_row;
 273                         __asm {
 274                                 push edi
 275                                 push esi
 276
 277                                 mov edi, dstp
 278                                 mov esi, srcp
 279                                 call dword ptr code
 280
 281                                 pop esi
 282                                 pop edi
 283                         }
 284                 }
 285 #else
 286 #error Need inline assembly for this compiler
 287 #endif
 288 #endif /* __GNUC__ */
 289                         break;
 290                 }
 291 #else
 292                 switch (bpp) {
 293                     case 1:
 294                         copy_row1(srcp, srcrect->w, dstp, dstrect->w);
 295                         break;
 296                     case 2:
 297                         copy_row2((Uint16 *)srcp, srcrect->w,
 298                                   (Uint16 *)dstp, dstrect->w);
 299                         break;
 300                     case 3:
 301                         copy_row3(srcp, srcrect->w, dstp, dstrect->w);
 302                         break;
 303                     case 4:
 304                         copy_row4((Uint32 *)srcp, srcrect->w,
 305                                   (Uint32 *)dstp, dstrect->w);
 306                         break;
 307                 }
 308 #endif
 309                 pos += inc;
 310         }
 311         return(0);
 312 }
 313