src/video/SDL_blit.h
author Sam Lantinga <slouken@libsdl.org>
Sun, 01 Jan 2017 18:33:28 -0800
changeset 10737 3406a0f8b041
parent 10638 d11daa346140
child 10754 6285a56f6729
permissions -rw-r--r--
Updated copyright for 2017
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2017 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 #include "../SDL_internal.h"
    22 
    23 #ifndef SDL_blit_h_
    24 #define SDL_blit_h_
    25 
    26 #include "SDL_cpuinfo.h"
    27 #include "SDL_endian.h"
    28 #include "SDL_surface.h"
    29 
    30 /* Table to do pixel byte expansion */
    31 extern Uint8* SDL_expand_byte[9];
    32 
    33 /* SDL blit copy flags */
    34 #define SDL_COPY_MODULATE_COLOR     0x00000001
    35 #define SDL_COPY_MODULATE_ALPHA     0x00000002
    36 #define SDL_COPY_BLEND              0x00000010
    37 #define SDL_COPY_ADD                0x00000020
    38 #define SDL_COPY_MOD                0x00000040
    39 #define SDL_COPY_COLORKEY           0x00000100
    40 #define SDL_COPY_NEAREST            0x00000200
    41 #define SDL_COPY_RLE_DESIRED        0x00001000
    42 #define SDL_COPY_RLE_COLORKEY       0x00002000
    43 #define SDL_COPY_RLE_ALPHAKEY       0x00004000
    44 #define SDL_COPY_RLE_MASK           (SDL_COPY_RLE_DESIRED|SDL_COPY_RLE_COLORKEY|SDL_COPY_RLE_ALPHAKEY)
    45 
    46 /* SDL blit CPU flags */
    47 #define SDL_CPU_ANY                 0x00000000
    48 #define SDL_CPU_MMX                 0x00000001
    49 #define SDL_CPU_3DNOW               0x00000002
    50 #define SDL_CPU_SSE                 0x00000004
    51 #define SDL_CPU_SSE2                0x00000008
    52 #define SDL_CPU_ALTIVEC_PREFETCH    0x00000010
    53 #define SDL_CPU_ALTIVEC_NOPREFETCH  0x00000020
    54 
    55 typedef struct
    56 {
    57     Uint8 *src;
    58     int src_w, src_h;
    59     int src_pitch;
    60     int src_skip;
    61     Uint8 *dst;
    62     int dst_w, dst_h;
    63     int dst_pitch;
    64     int dst_skip;
    65     SDL_PixelFormat *src_fmt;
    66     SDL_PixelFormat *dst_fmt;
    67     Uint8 *table;
    68     int flags;
    69     Uint32 colorkey;
    70     Uint8 r, g, b, a;
    71 } SDL_BlitInfo;
    72 
    73 typedef void (SDLCALL * SDL_BlitFunc) (SDL_BlitInfo * info);
    74 
    75 typedef struct
    76 {
    77     Uint32 src_format;
    78     Uint32 dst_format;
    79     int flags;
    80     int cpu;
    81     SDL_BlitFunc func;
    82 } SDL_BlitFuncEntry;
    83 
    84 /* Blit mapping definition */
    85 typedef struct SDL_BlitMap
    86 {
    87     SDL_Surface *dst;
    88     int identity;
    89     SDL_blit blit;
    90     void *data;
    91     SDL_BlitInfo info;
    92 
    93     /* the version count matches the destination; mismatch indicates
    94        an invalid mapping */
    95     Uint32 dst_palette_version;
    96     Uint32 src_palette_version;
    97 } SDL_BlitMap;
    98 
    99 /* Functions found in SDL_blit.c */
   100 extern int SDL_CalculateBlit(SDL_Surface * surface);
   101 
   102 /* Functions found in SDL_blit_*.c */
   103 extern SDL_BlitFunc SDL_CalculateBlit0(SDL_Surface * surface);
   104 extern SDL_BlitFunc SDL_CalculateBlit1(SDL_Surface * surface);
   105 extern SDL_BlitFunc SDL_CalculateBlitN(SDL_Surface * surface);
   106 extern SDL_BlitFunc SDL_CalculateBlitA(SDL_Surface * surface);
   107 
   108 /*
   109  * Useful macros for blitting routines
   110  */
   111 
   112 #if defined(__GNUC__)
   113 #define DECLARE_ALIGNED(t,v,a)  t __attribute__((aligned(a))) v
   114 #elif defined(_MSC_VER)
   115 #define DECLARE_ALIGNED(t,v,a)  __declspec(align(a)) t v
   116 #else
   117 #define DECLARE_ALIGNED(t,v,a)  t v
   118 #endif
   119 
   120 /* Load pixel of the specified format from a buffer and get its R-G-B values */
   121 #define RGB_FROM_PIXEL(Pixel, fmt, r, g, b)                             \
   122 {                                                                       \
   123     r = SDL_expand_byte[fmt->Rloss][((Pixel&fmt->Rmask)>>fmt->Rshift)]; \
   124     g = SDL_expand_byte[fmt->Gloss][((Pixel&fmt->Gmask)>>fmt->Gshift)]; \
   125     b = SDL_expand_byte[fmt->Bloss][((Pixel&fmt->Bmask)>>fmt->Bshift)]; \
   126 }
   127 #define RGB_FROM_RGB565(Pixel, r, g, b)                                 \
   128     {                                                                   \
   129     r = SDL_expand_byte[3][((Pixel&0xF800)>>11)];                       \
   130     g = SDL_expand_byte[2][((Pixel&0x07E0)>>5)];                        \
   131     b = SDL_expand_byte[3][(Pixel&0x001F)];                             \
   132 }
   133 #define RGB_FROM_RGB555(Pixel, r, g, b)                                 \
   134 {                                                                       \
   135     r = SDL_expand_byte[3][((Pixel&0x7C00)>>10)];                       \
   136     g = SDL_expand_byte[3][((Pixel&0x03E0)>>5)];                        \
   137     b = SDL_expand_byte[3][(Pixel&0x001F)];                             \
   138 }
   139 #define RGB_FROM_RGB888(Pixel, r, g, b)                                 \
   140 {                                                                       \
   141     r = ((Pixel&0xFF0000)>>16);                                         \
   142     g = ((Pixel&0xFF00)>>8);                                            \
   143     b = (Pixel&0xFF);                                                   \
   144 }
   145 #define RETRIEVE_RGB_PIXEL(buf, bpp, Pixel)                             \
   146 do {                                                                    \
   147     switch (bpp) {                                                      \
   148         case 1:                                                         \
   149             Pixel = *((Uint8 *)(buf));                                  \
   150         break;                                                          \
   151                                                                         \
   152         case 2:                                                         \
   153             Pixel = *((Uint16 *)(buf));                                 \
   154         break;                                                          \
   155                                                                         \
   156         case 3: {                                                       \
   157             Uint8 *B = (Uint8 *)(buf);                                  \
   158             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   159                 Pixel = B[0] + (B[1] << 8) + (B[2] << 16);              \
   160             } else {                                                    \
   161                 Pixel = (B[0] << 16) + (B[1] << 8) + B[2];              \
   162             }                                                           \
   163         }                                                               \
   164         break;                                                          \
   165                                                                         \
   166         case 4:                                                         \
   167             Pixel = *((Uint32 *)(buf));                                 \
   168         break;                                                          \
   169                                                                         \
   170         default:                                                        \
   171                 Pixel = 0; /* stop gcc complaints */                    \
   172         break;                                                          \
   173     }                                                                   \
   174 } while (0)
   175 
   176 #define DISEMBLE_RGB(buf, bpp, fmt, Pixel, r, g, b)                     \
   177 do {                                                                    \
   178     switch (bpp) {                                                      \
   179         case 1:                                                         \
   180             Pixel = *((Uint8 *)(buf));                                  \
   181             RGB_FROM_PIXEL(Pixel, fmt, r, g, b);                        \
   182         break;                                                          \
   183                                                                         \
   184         case 2:                                                         \
   185             Pixel = *((Uint16 *)(buf));                                 \
   186             RGB_FROM_PIXEL(Pixel, fmt, r, g, b);                        \
   187         break;                                                          \
   188                                                                         \
   189         case 3: {                                                       \
   190             Pixel = 0;                                                  \
   191             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   192                 r = *((buf)+fmt->Rshift/8);                             \
   193                 g = *((buf)+fmt->Gshift/8);                             \
   194                 b = *((buf)+fmt->Bshift/8);                             \
   195             } else {                                                    \
   196                 r = *((buf)+2-fmt->Rshift/8);                           \
   197                 g = *((buf)+2-fmt->Gshift/8);                           \
   198                 b = *((buf)+2-fmt->Bshift/8);                           \
   199             }                                                           \
   200         }                                                               \
   201         break;                                                          \
   202                                                                         \
   203         case 4:                                                         \
   204             Pixel = *((Uint32 *)(buf));                                 \
   205             RGB_FROM_PIXEL(Pixel, fmt, r, g, b);                        \
   206         break;                                                          \
   207                                                                         \
   208         default:                                                        \
   209                 /* stop gcc complaints */                               \
   210                 Pixel = 0;                                              \
   211                 r = g = b = 0;                                          \
   212         break;                                                          \
   213     }                                                                   \
   214 } while (0)
   215 
   216 /* Assemble R-G-B values into a specified pixel format and store them */
   217 #define PIXEL_FROM_RGB(Pixel, fmt, r, g, b)                             \
   218 {                                                                       \
   219     Pixel = ((r>>fmt->Rloss)<<fmt->Rshift)|                             \
   220         ((g>>fmt->Gloss)<<fmt->Gshift)|                                 \
   221         ((b>>fmt->Bloss)<<fmt->Bshift)|                                 \
   222         fmt->Amask;                                                     \
   223 }
   224 #define RGB565_FROM_RGB(Pixel, r, g, b)                                 \
   225 {                                                                       \
   226     Pixel = ((r>>3)<<11)|((g>>2)<<5)|(b>>3);                            \
   227 }
   228 #define RGB555_FROM_RGB(Pixel, r, g, b)                                 \
   229 {                                                                       \
   230     Pixel = ((r>>3)<<10)|((g>>3)<<5)|(b>>3);                            \
   231 }
   232 #define RGB888_FROM_RGB(Pixel, r, g, b)                                 \
   233 {                                                                       \
   234     Pixel = (r<<16)|(g<<8)|b;                                           \
   235 }
   236 #define ARGB8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   237 {                                                                       \
   238     Pixel = (a<<24)|(r<<16)|(g<<8)|b;                                   \
   239 }
   240 #define RGBA8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   241 {                                                                       \
   242     Pixel = (r<<24)|(g<<16)|(b<<8)|a;                                   \
   243 }
   244 #define ABGR8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   245 {                                                                       \
   246     Pixel = (a<<24)|(b<<16)|(g<<8)|r;                                   \
   247 }
   248 #define BGRA8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   249 {                                                                       \
   250     Pixel = (b<<24)|(g<<16)|(r<<8)|a;                                   \
   251 }
   252 #define ARGB2101010_FROM_RGBA(Pixel, r, g, b, a)                        \
   253 {                                                                       \
   254     r = r ? ((r << 2) | 0x3) : 0;                                       \
   255     g = g ? ((g << 2) | 0x3) : 0;                                       \
   256     b = b ? ((b << 2) | 0x3) : 0;                                       \
   257     a = (a * 3) / 255;                                                  \
   258     Pixel = (a<<30)|(r<<20)|(g<<10)|b;                                  \
   259 }
   260 #define ASSEMBLE_RGB(buf, bpp, fmt, r, g, b)                            \
   261 {                                                                       \
   262     switch (bpp) {                                                      \
   263         case 1: {                                                       \
   264             Uint8 Pixel;                                                \
   265                                                                         \
   266             PIXEL_FROM_RGB(Pixel, fmt, r, g, b);                        \
   267             *((Uint8 *)(buf)) = Pixel;                                  \
   268         }                                                               \
   269         break;                                                          \
   270                                                                         \
   271         case 2: {                                                       \
   272             Uint16 Pixel;                                               \
   273                                                                         \
   274             PIXEL_FROM_RGB(Pixel, fmt, r, g, b);                        \
   275             *((Uint16 *)(buf)) = Pixel;                                 \
   276         }                                                               \
   277         break;                                                          \
   278                                                                         \
   279         case 3: {                                                       \
   280             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   281                 *((buf)+fmt->Rshift/8) = r;                             \
   282                 *((buf)+fmt->Gshift/8) = g;                             \
   283                 *((buf)+fmt->Bshift/8) = b;                             \
   284             } else {                                                    \
   285                 *((buf)+2-fmt->Rshift/8) = r;                           \
   286                 *((buf)+2-fmt->Gshift/8) = g;                           \
   287                 *((buf)+2-fmt->Bshift/8) = b;                           \
   288             }                                                           \
   289         }                                                               \
   290         break;                                                          \
   291                                                                         \
   292         case 4: {                                                       \
   293             Uint32 Pixel;                                               \
   294                                                                         \
   295             PIXEL_FROM_RGB(Pixel, fmt, r, g, b);                        \
   296             *((Uint32 *)(buf)) = Pixel;                                 \
   297         }                                                               \
   298         break;                                                          \
   299     }                                                                   \
   300 }
   301 
   302 /* FIXME: Should we rescale alpha into 0..255 here? */
   303 #define RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a)                         \
   304 {                                                                       \
   305     r = SDL_expand_byte[fmt->Rloss][((Pixel&fmt->Rmask)>>fmt->Rshift)]; \
   306     g = SDL_expand_byte[fmt->Gloss][((Pixel&fmt->Gmask)>>fmt->Gshift)]; \
   307     b = SDL_expand_byte[fmt->Bloss][((Pixel&fmt->Bmask)>>fmt->Bshift)]; \
   308     a = SDL_expand_byte[fmt->Aloss][((Pixel&fmt->Amask)>>fmt->Ashift)]; \
   309 }
   310 #define RGBA_FROM_8888(Pixel, fmt, r, g, b, a)                          \
   311 {                                                                       \
   312     r = (Pixel&fmt->Rmask)>>fmt->Rshift;                                \
   313     g = (Pixel&fmt->Gmask)>>fmt->Gshift;                                \
   314     b = (Pixel&fmt->Bmask)>>fmt->Bshift;                                \
   315     a = (Pixel&fmt->Amask)>>fmt->Ashift;                                \
   316 }
   317 #define RGBA_FROM_RGBA8888(Pixel, r, g, b, a)                           \
   318 {                                                                       \
   319     r = (Pixel>>24);                                                    \
   320     g = ((Pixel>>16)&0xFF);                                             \
   321     b = ((Pixel>>8)&0xFF);                                              \
   322     a = (Pixel&0xFF);                                                   \
   323 }
   324 #define RGBA_FROM_ARGB8888(Pixel, r, g, b, a)                           \
   325 {                                                                       \
   326     r = ((Pixel>>16)&0xFF);                                             \
   327     g = ((Pixel>>8)&0xFF);                                              \
   328     b = (Pixel&0xFF);                                                   \
   329     a = (Pixel>>24);                                                    \
   330 }
   331 #define RGBA_FROM_ABGR8888(Pixel, r, g, b, a)                           \
   332 {                                                                       \
   333     r = (Pixel&0xFF);                                                   \
   334     g = ((Pixel>>8)&0xFF);                                              \
   335     b = ((Pixel>>16)&0xFF);                                             \
   336     a = (Pixel>>24);                                                    \
   337 }
   338 #define RGBA_FROM_BGRA8888(Pixel, r, g, b, a)                           \
   339 {                                                                       \
   340     r = ((Pixel>>8)&0xFF);                                              \
   341     g = ((Pixel>>16)&0xFF);                                             \
   342     b = (Pixel>>24);                                                    \
   343     a = (Pixel&0xFF);                                                   \
   344 }
   345 #define RGBA_FROM_ARGB2101010(Pixel, r, g, b, a)                        \
   346 {                                                                       \
   347     r = ((Pixel>>22)&0xFF);                                             \
   348     g = ((Pixel>>12)&0xFF);                                             \
   349     b = ((Pixel>>2)&0xFF);                                              \
   350     a = SDL_expand_byte[6][(Pixel>>30)];                                \
   351 }
   352 #define DISEMBLE_RGBA(buf, bpp, fmt, Pixel, r, g, b, a)                 \
   353 do {                                                                    \
   354     switch (bpp) {                                                      \
   355         case 1:                                                         \
   356             Pixel = *((Uint8 *)(buf));                                  \
   357             RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a);                    \
   358         break;                                                          \
   359                                                                         \
   360         case 2:                                                         \
   361             Pixel = *((Uint16 *)(buf));                                 \
   362             RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a);                    \
   363         break;                                                          \
   364                                                                         \
   365         case 3: {                                                       \
   366             Pixel = 0;                                                  \
   367             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   368                 r = *((buf)+fmt->Rshift/8);                             \
   369                 g = *((buf)+fmt->Gshift/8);                             \
   370                 b = *((buf)+fmt->Bshift/8);                             \
   371             } else {                                                    \
   372                 r = *((buf)+2-fmt->Rshift/8);                           \
   373                 g = *((buf)+2-fmt->Gshift/8);                           \
   374                 b = *((buf)+2-fmt->Bshift/8);                           \
   375             }                                                           \
   376             a = 0xFF;                                                   \
   377         }                                                               \
   378         break;                                                          \
   379                                                                         \
   380         case 4:                                                         \
   381             Pixel = *((Uint32 *)(buf));                                 \
   382             RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a);                    \
   383         break;                                                          \
   384                                                                         \
   385         default:                                                        \
   386             /* stop gcc complaints */                                   \
   387             Pixel = 0;                                                  \
   388             r = g = b = a = 0;                                          \
   389         break;                                                          \
   390     }                                                                   \
   391 } while (0)
   392 
   393 /* FIXME: this isn't correct, especially for Alpha (maximum != 255) */
   394 #define PIXEL_FROM_RGBA(Pixel, fmt, r, g, b, a)                         \
   395 {                                                                       \
   396     Pixel = ((r>>fmt->Rloss)<<fmt->Rshift)|                             \
   397         ((g>>fmt->Gloss)<<fmt->Gshift)|                                 \
   398         ((b>>fmt->Bloss)<<fmt->Bshift)|                                 \
   399         ((a>>fmt->Aloss)<<fmt->Ashift);                                 \
   400 }
   401 #define ASSEMBLE_RGBA(buf, bpp, fmt, r, g, b, a)                        \
   402 {                                                                       \
   403     switch (bpp) {                                                      \
   404         case 1: {                                                       \
   405             Uint8 _pixel;                                               \
   406                                                                         \
   407             PIXEL_FROM_RGBA(_pixel, fmt, r, g, b, a);                   \
   408             *((Uint8 *)(buf)) = _pixel;                                 \
   409         }                                                               \
   410         break;                                                          \
   411                                                                         \
   412         case 2: {                                                       \
   413             Uint16 _pixel;                                              \
   414                                                                         \
   415             PIXEL_FROM_RGBA(_pixel, fmt, r, g, b, a);                   \
   416             *((Uint16 *)(buf)) = _pixel;                                \
   417         }                                                               \
   418         break;                                                          \
   419                                                                         \
   420         case 3: {                                                       \
   421             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   422                 *((buf)+fmt->Rshift/8) = r;                             \
   423                 *((buf)+fmt->Gshift/8) = g;                             \
   424                 *((buf)+fmt->Bshift/8) = b;                             \
   425             } else {                                                    \
   426                 *((buf)+2-fmt->Rshift/8) = r;                           \
   427                 *((buf)+2-fmt->Gshift/8) = g;                           \
   428                 *((buf)+2-fmt->Bshift/8) = b;                           \
   429             }                                                           \
   430         }                                                               \
   431         break;                                                          \
   432                                                                         \
   433         case 4: {                                                       \
   434             Uint32 _pixel;                                              \
   435                                                                         \
   436             PIXEL_FROM_RGBA(_pixel, fmt, r, g, b, a);                   \
   437             *((Uint32 *)(buf)) = _pixel;                                \
   438         }                                                               \
   439         break;                                                          \
   440     }                                                                   \
   441 }
   442 
   443 /* Blend the RGB values of two pixels with an alpha value */
   444 #define ALPHA_BLEND_RGB(sR, sG, sB, A, dR, dG, dB)                      \
   445 do {                                                                    \
   446     dR = ((((unsigned)(sR-dR)*(unsigned)A)/255)+dR);                    \
   447     dG = ((((unsigned)(sG-dG)*(unsigned)A)/255)+dG);                    \
   448     dB = ((((unsigned)(sB-dB)*(unsigned)A)/255)+dB);                    \
   449 } while(0)
   450 
   451 
   452 /* Blend the RGBA values of two pixels */
   453 #define ALPHA_BLEND_RGBA(sR, sG, sB, sA, dR, dG, dB, dA)                \
   454 do {                                                                    \
   455     dR = ((((unsigned)(sR-dR)*(unsigned)sA)/255)+dR);                   \
   456     dG = ((((unsigned)(sG-dG)*(unsigned)sA)/255)+dG);                   \
   457     dB = ((((unsigned)(sB-dB)*(unsigned)sA)/255)+dB);                   \
   458     dA = ((unsigned)sA+(unsigned)dA-((unsigned)sA*dA)/255);             \
   459 } while(0)
   460 
   461 
   462 /* This is a very useful loop for optimizing blitters */
   463 #if defined(_MSC_VER) && (_MSC_VER == 1300)
   464 /* There's a bug in the Visual C++ 7 optimizer when compiling this code */
   465 #else
   466 #define USE_DUFFS_LOOP
   467 #endif
   468 #ifdef USE_DUFFS_LOOP
   469 
   470 /* 8-times unrolled loop */
   471 #define DUFFS_LOOP8(pixel_copy_increment, width)                        \
   472 { int n = (width+7)/8;                                                  \
   473     switch (width & 7) {                                                \
   474     case 0: do {    pixel_copy_increment;                               \
   475     case 7:     pixel_copy_increment;                                   \
   476     case 6:     pixel_copy_increment;                                   \
   477     case 5:     pixel_copy_increment;                                   \
   478     case 4:     pixel_copy_increment;                                   \
   479     case 3:     pixel_copy_increment;                                   \
   480     case 2:     pixel_copy_increment;                                   \
   481     case 1:     pixel_copy_increment;                                   \
   482         } while ( --n > 0 );                                            \
   483     }                                                                   \
   484 }
   485 
   486 /* 4-times unrolled loop */
   487 #define DUFFS_LOOP4(pixel_copy_increment, width)                        \
   488 { int n = (width+3)/4;                                                  \
   489     switch (width & 3) {                                                \
   490     case 0: do {    pixel_copy_increment;                               \
   491     case 3:     pixel_copy_increment;                                   \
   492     case 2:     pixel_copy_increment;                                   \
   493     case 1:     pixel_copy_increment;                                   \
   494         } while (--n > 0);                                              \
   495     }                                                                   \
   496 }
   497 
   498 /* Use the 8-times version of the loop by default */
   499 #define DUFFS_LOOP(pixel_copy_increment, width)                         \
   500     DUFFS_LOOP8(pixel_copy_increment, width)
   501 
   502 /* Special version of Duff's device for even more optimization */
   503 #define DUFFS_LOOP_124(pixel_copy_increment1,                           \
   504                        pixel_copy_increment2,                           \
   505                        pixel_copy_increment4, width)                    \
   506 { int n = width;                                                        \
   507     if (n & 1) {                                                        \
   508         pixel_copy_increment1; n -= 1;                                  \
   509     }                                                                   \
   510     if (n & 2) {                                                        \
   511         pixel_copy_increment2; n -= 2;                                  \
   512     }                                                                   \
   513     if (n & 4) {                                                        \
   514         pixel_copy_increment4; n -= 4;                                  \
   515     }                                                                   \
   516     if (n) {                                                            \
   517         n /= 8;                                                         \
   518         do {                                                            \
   519             pixel_copy_increment4;                                      \
   520             pixel_copy_increment4;                                      \
   521         } while (--n > 0);                                              \
   522     }                                                                   \
   523 }
   524 
   525 #else
   526 
   527 /* Don't use Duff's device to unroll loops */
   528 #define DUFFS_LOOP(pixel_copy_increment, width)                         \
   529 { int n;                                                                \
   530     for ( n=width; n > 0; --n ) {                                       \
   531         pixel_copy_increment;                                           \
   532     }                                                                   \
   533 }
   534 #define DUFFS_LOOP8(pixel_copy_increment, width)                        \
   535     DUFFS_LOOP(pixel_copy_increment, width)
   536 #define DUFFS_LOOP4(pixel_copy_increment, width)                        \
   537     DUFFS_LOOP(pixel_copy_increment, width)
   538 #define DUFFS_LOOP_124(pixel_copy_increment1,                           \
   539                        pixel_copy_increment2,                           \
   540                        pixel_copy_increment4, width)                    \
   541     DUFFS_LOOP(pixel_copy_increment1, width)
   542 
   543 #endif /* USE_DUFFS_LOOP */
   544 
   545 /* Prevent Visual C++ 6.0 from printing out stupid warnings */
   546 #if defined(_MSC_VER) && (_MSC_VER >= 600)
   547 #pragma warning(disable: 4550)
   548 #endif
   549 
   550 #endif /* SDL_blit_h_ */
   551 
   552 /* vi: set ts=4 sw=4 expandtab: */