src/video/SDL_blit.h
author Ryan C. Gordon <icculus@icculus.org>
Tue, 23 Oct 2018 01:34:03 -0400
branchSDL-ryan-batching-renderer
changeset 12352 2b1707cc57fc
parent 11811 5d94cb6b24d3
child 12273 c522b61334f1
permissions -rw-r--r--
render: Add floating point versions of various draw APIs.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2018 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 (*SDL_BlitFunc) (SDL_BlitInfo *info);
    74 
    75 
    76 typedef struct
    77 {
    78     Uint32 src_format;
    79     Uint32 dst_format;
    80     int flags;
    81     int cpu;
    82     SDL_BlitFunc func;
    83 } SDL_BlitFuncEntry;
    84 
    85 /* Blit mapping definition */
    86 typedef struct SDL_BlitMap
    87 {
    88     SDL_Surface *dst;
    89     int identity;
    90     SDL_blit blit;
    91     void *data;
    92     SDL_BlitInfo info;
    93 
    94     /* the version count matches the destination; mismatch indicates
    95        an invalid mapping */
    96     Uint32 dst_palette_version;
    97     Uint32 src_palette_version;
    98 } SDL_BlitMap;
    99 
   100 /* Functions found in SDL_blit.c */
   101 extern int SDL_CalculateBlit(SDL_Surface * surface);
   102 
   103 /* Functions found in SDL_blit_*.c */
   104 extern SDL_BlitFunc SDL_CalculateBlit0(SDL_Surface * surface);
   105 extern SDL_BlitFunc SDL_CalculateBlit1(SDL_Surface * surface);
   106 extern SDL_BlitFunc SDL_CalculateBlitN(SDL_Surface * surface);
   107 extern SDL_BlitFunc SDL_CalculateBlitA(SDL_Surface * surface);
   108 
   109 /*
   110  * Useful macros for blitting routines
   111  */
   112 
   113 #if defined(__GNUC__)
   114 #define DECLARE_ALIGNED(t,v,a)  t __attribute__((aligned(a))) v
   115 #elif defined(_MSC_VER)
   116 #define DECLARE_ALIGNED(t,v,a)  __declspec(align(a)) t v
   117 #else
   118 #define DECLARE_ALIGNED(t,v,a)  t v
   119 #endif
   120 
   121 /* Load pixel of the specified format from a buffer and get its R-G-B values */
   122 #define RGB_FROM_PIXEL(Pixel, fmt, r, g, b)                             \
   123 {                                                                       \
   124     r = SDL_expand_byte[fmt->Rloss][((Pixel&fmt->Rmask)>>fmt->Rshift)]; \
   125     g = SDL_expand_byte[fmt->Gloss][((Pixel&fmt->Gmask)>>fmt->Gshift)]; \
   126     b = SDL_expand_byte[fmt->Bloss][((Pixel&fmt->Bmask)>>fmt->Bshift)]; \
   127 }
   128 #define RGB_FROM_RGB565(Pixel, r, g, b)                                 \
   129     {                                                                   \
   130     r = SDL_expand_byte[3][((Pixel&0xF800)>>11)];                       \
   131     g = SDL_expand_byte[2][((Pixel&0x07E0)>>5)];                        \
   132     b = SDL_expand_byte[3][(Pixel&0x001F)];                             \
   133 }
   134 #define RGB_FROM_RGB555(Pixel, r, g, b)                                 \
   135 {                                                                       \
   136     r = SDL_expand_byte[3][((Pixel&0x7C00)>>10)];                       \
   137     g = SDL_expand_byte[3][((Pixel&0x03E0)>>5)];                        \
   138     b = SDL_expand_byte[3][(Pixel&0x001F)];                             \
   139 }
   140 #define RGB_FROM_RGB888(Pixel, r, g, b)                                 \
   141 {                                                                       \
   142     r = ((Pixel&0xFF0000)>>16);                                         \
   143     g = ((Pixel&0xFF00)>>8);                                            \
   144     b = (Pixel&0xFF);                                                   \
   145 }
   146 #define RETRIEVE_RGB_PIXEL(buf, bpp, Pixel)                             \
   147 do {                                                                    \
   148     switch (bpp) {                                                      \
   149         case 1:                                                         \
   150             Pixel = *((Uint8 *)(buf));                                  \
   151         break;                                                          \
   152                                                                         \
   153         case 2:                                                         \
   154             Pixel = *((Uint16 *)(buf));                                 \
   155         break;                                                          \
   156                                                                         \
   157         case 3: {                                                       \
   158             Uint8 *B = (Uint8 *)(buf);                                  \
   159             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   160                 Pixel = B[0] + (B[1] << 8) + (B[2] << 16);              \
   161             } else {                                                    \
   162                 Pixel = (B[0] << 16) + (B[1] << 8) + B[2];              \
   163             }                                                           \
   164         }                                                               \
   165         break;                                                          \
   166                                                                         \
   167         case 4:                                                         \
   168             Pixel = *((Uint32 *)(buf));                                 \
   169         break;                                                          \
   170                                                                         \
   171         default:                                                        \
   172                 Pixel = 0; /* stop gcc complaints */                    \
   173         break;                                                          \
   174     }                                                                   \
   175 } while (0)
   176 
   177 #define DISEMBLE_RGB(buf, bpp, fmt, Pixel, r, g, b)                     \
   178 do {                                                                    \
   179     switch (bpp) {                                                      \
   180         case 1:                                                         \
   181             Pixel = *((Uint8 *)(buf));                                  \
   182             RGB_FROM_PIXEL(Pixel, fmt, r, g, b);                        \
   183         break;                                                          \
   184                                                                         \
   185         case 2:                                                         \
   186             Pixel = *((Uint16 *)(buf));                                 \
   187             RGB_FROM_PIXEL(Pixel, fmt, r, g, b);                        \
   188         break;                                                          \
   189                                                                         \
   190         case 3: {                                                       \
   191             Pixel = 0;                                                  \
   192             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   193                 r = *((buf)+fmt->Rshift/8);                             \
   194                 g = *((buf)+fmt->Gshift/8);                             \
   195                 b = *((buf)+fmt->Bshift/8);                             \
   196             } else {                                                    \
   197                 r = *((buf)+2-fmt->Rshift/8);                           \
   198                 g = *((buf)+2-fmt->Gshift/8);                           \
   199                 b = *((buf)+2-fmt->Bshift/8);                           \
   200             }                                                           \
   201         }                                                               \
   202         break;                                                          \
   203                                                                         \
   204         case 4:                                                         \
   205             Pixel = *((Uint32 *)(buf));                                 \
   206             RGB_FROM_PIXEL(Pixel, fmt, r, g, b);                        \
   207         break;                                                          \
   208                                                                         \
   209         default:                                                        \
   210                 /* stop gcc complaints */                               \
   211                 Pixel = 0;                                              \
   212                 r = g = b = 0;                                          \
   213         break;                                                          \
   214     }                                                                   \
   215 } while (0)
   216 
   217 /* Assemble R-G-B values into a specified pixel format and store them */
   218 #define PIXEL_FROM_RGB(Pixel, fmt, r, g, b)                             \
   219 {                                                                       \
   220     Pixel = ((r>>fmt->Rloss)<<fmt->Rshift)|                             \
   221         ((g>>fmt->Gloss)<<fmt->Gshift)|                                 \
   222         ((b>>fmt->Bloss)<<fmt->Bshift)|                                 \
   223         fmt->Amask;                                                     \
   224 }
   225 #define RGB565_FROM_RGB(Pixel, r, g, b)                                 \
   226 {                                                                       \
   227     Pixel = ((r>>3)<<11)|((g>>2)<<5)|(b>>3);                            \
   228 }
   229 #define RGB555_FROM_RGB(Pixel, r, g, b)                                 \
   230 {                                                                       \
   231     Pixel = ((r>>3)<<10)|((g>>3)<<5)|(b>>3);                            \
   232 }
   233 #define RGB888_FROM_RGB(Pixel, r, g, b)                                 \
   234 {                                                                       \
   235     Pixel = (r<<16)|(g<<8)|b;                                           \
   236 }
   237 #define ARGB8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   238 {                                                                       \
   239     Pixel = (a<<24)|(r<<16)|(g<<8)|b;                                   \
   240 }
   241 #define RGBA8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   242 {                                                                       \
   243     Pixel = (r<<24)|(g<<16)|(b<<8)|a;                                   \
   244 }
   245 #define ABGR8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   246 {                                                                       \
   247     Pixel = (a<<24)|(b<<16)|(g<<8)|r;                                   \
   248 }
   249 #define BGRA8888_FROM_RGBA(Pixel, r, g, b, a)                           \
   250 {                                                                       \
   251     Pixel = (b<<24)|(g<<16)|(r<<8)|a;                                   \
   252 }
   253 #define ARGB2101010_FROM_RGBA(Pixel, r, g, b, a)                        \
   254 {                                                                       \
   255     r = r ? ((r << 2) | 0x3) : 0;                                       \
   256     g = g ? ((g << 2) | 0x3) : 0;                                       \
   257     b = b ? ((b << 2) | 0x3) : 0;                                       \
   258     a = (a * 3) / 255;                                                  \
   259     Pixel = (a<<30)|(r<<20)|(g<<10)|b;                                  \
   260 }
   261 #define ASSEMBLE_RGB(buf, bpp, fmt, r, g, b)                            \
   262 {                                                                       \
   263     switch (bpp) {                                                      \
   264         case 1: {                                                       \
   265             Uint8 Pixel;                                                \
   266                                                                         \
   267             PIXEL_FROM_RGB(Pixel, fmt, r, g, b);                        \
   268             *((Uint8 *)(buf)) = Pixel;                                  \
   269         }                                                               \
   270         break;                                                          \
   271                                                                         \
   272         case 2: {                                                       \
   273             Uint16 Pixel;                                               \
   274                                                                         \
   275             PIXEL_FROM_RGB(Pixel, fmt, r, g, b);                        \
   276             *((Uint16 *)(buf)) = Pixel;                                 \
   277         }                                                               \
   278         break;                                                          \
   279                                                                         \
   280         case 3: {                                                       \
   281             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   282                 *((buf)+fmt->Rshift/8) = r;                             \
   283                 *((buf)+fmt->Gshift/8) = g;                             \
   284                 *((buf)+fmt->Bshift/8) = b;                             \
   285             } else {                                                    \
   286                 *((buf)+2-fmt->Rshift/8) = r;                           \
   287                 *((buf)+2-fmt->Gshift/8) = g;                           \
   288                 *((buf)+2-fmt->Bshift/8) = b;                           \
   289             }                                                           \
   290         }                                                               \
   291         break;                                                          \
   292                                                                         \
   293         case 4: {                                                       \
   294             Uint32 Pixel;                                               \
   295                                                                         \
   296             PIXEL_FROM_RGB(Pixel, fmt, r, g, b);                        \
   297             *((Uint32 *)(buf)) = Pixel;                                 \
   298         }                                                               \
   299         break;                                                          \
   300     }                                                                   \
   301 }
   302 
   303 /* FIXME: Should we rescale alpha into 0..255 here? */
   304 #define RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a)                         \
   305 {                                                                       \
   306     r = SDL_expand_byte[fmt->Rloss][((Pixel&fmt->Rmask)>>fmt->Rshift)]; \
   307     g = SDL_expand_byte[fmt->Gloss][((Pixel&fmt->Gmask)>>fmt->Gshift)]; \
   308     b = SDL_expand_byte[fmt->Bloss][((Pixel&fmt->Bmask)>>fmt->Bshift)]; \
   309     a = SDL_expand_byte[fmt->Aloss][((Pixel&fmt->Amask)>>fmt->Ashift)]; \
   310 }
   311 #define RGBA_FROM_8888(Pixel, fmt, r, g, b, a)                          \
   312 {                                                                       \
   313     r = (Pixel&fmt->Rmask)>>fmt->Rshift;                                \
   314     g = (Pixel&fmt->Gmask)>>fmt->Gshift;                                \
   315     b = (Pixel&fmt->Bmask)>>fmt->Bshift;                                \
   316     a = (Pixel&fmt->Amask)>>fmt->Ashift;                                \
   317 }
   318 #define RGBA_FROM_RGBA8888(Pixel, r, g, b, a)                           \
   319 {                                                                       \
   320     r = (Pixel>>24);                                                    \
   321     g = ((Pixel>>16)&0xFF);                                             \
   322     b = ((Pixel>>8)&0xFF);                                              \
   323     a = (Pixel&0xFF);                                                   \
   324 }
   325 #define RGBA_FROM_ARGB8888(Pixel, r, g, b, a)                           \
   326 {                                                                       \
   327     r = ((Pixel>>16)&0xFF);                                             \
   328     g = ((Pixel>>8)&0xFF);                                              \
   329     b = (Pixel&0xFF);                                                   \
   330     a = (Pixel>>24);                                                    \
   331 }
   332 #define RGBA_FROM_ABGR8888(Pixel, r, g, b, a)                           \
   333 {                                                                       \
   334     r = (Pixel&0xFF);                                                   \
   335     g = ((Pixel>>8)&0xFF);                                              \
   336     b = ((Pixel>>16)&0xFF);                                             \
   337     a = (Pixel>>24);                                                    \
   338 }
   339 #define RGBA_FROM_BGRA8888(Pixel, r, g, b, a)                           \
   340 {                                                                       \
   341     r = ((Pixel>>8)&0xFF);                                              \
   342     g = ((Pixel>>16)&0xFF);                                             \
   343     b = (Pixel>>24);                                                    \
   344     a = (Pixel&0xFF);                                                   \
   345 }
   346 #define RGBA_FROM_ARGB2101010(Pixel, r, g, b, a)                        \
   347 {                                                                       \
   348     r = ((Pixel>>22)&0xFF);                                             \
   349     g = ((Pixel>>12)&0xFF);                                             \
   350     b = ((Pixel>>2)&0xFF);                                              \
   351     a = SDL_expand_byte[6][(Pixel>>30)];                                \
   352 }
   353 #define DISEMBLE_RGBA(buf, bpp, fmt, Pixel, r, g, b, a)                 \
   354 do {                                                                    \
   355     switch (bpp) {                                                      \
   356         case 1:                                                         \
   357             Pixel = *((Uint8 *)(buf));                                  \
   358             RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a);                    \
   359         break;                                                          \
   360                                                                         \
   361         case 2:                                                         \
   362             Pixel = *((Uint16 *)(buf));                                 \
   363             RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a);                    \
   364         break;                                                          \
   365                                                                         \
   366         case 3: {                                                       \
   367             Pixel = 0;                                                  \
   368             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   369                 r = *((buf)+fmt->Rshift/8);                             \
   370                 g = *((buf)+fmt->Gshift/8);                             \
   371                 b = *((buf)+fmt->Bshift/8);                             \
   372             } else {                                                    \
   373                 r = *((buf)+2-fmt->Rshift/8);                           \
   374                 g = *((buf)+2-fmt->Gshift/8);                           \
   375                 b = *((buf)+2-fmt->Bshift/8);                           \
   376             }                                                           \
   377             a = 0xFF;                                                   \
   378         }                                                               \
   379         break;                                                          \
   380                                                                         \
   381         case 4:                                                         \
   382             Pixel = *((Uint32 *)(buf));                                 \
   383             RGBA_FROM_PIXEL(Pixel, fmt, r, g, b, a);                    \
   384         break;                                                          \
   385                                                                         \
   386         default:                                                        \
   387             /* stop gcc complaints */                                   \
   388             Pixel = 0;                                                  \
   389             r = g = b = a = 0;                                          \
   390         break;                                                          \
   391     }                                                                   \
   392 } while (0)
   393 
   394 /* FIXME: this isn't correct, especially for Alpha (maximum != 255) */
   395 #define PIXEL_FROM_RGBA(Pixel, fmt, r, g, b, a)                         \
   396 {                                                                       \
   397     Pixel = ((r>>fmt->Rloss)<<fmt->Rshift)|                             \
   398         ((g>>fmt->Gloss)<<fmt->Gshift)|                                 \
   399         ((b>>fmt->Bloss)<<fmt->Bshift)|                                 \
   400         ((a>>fmt->Aloss)<<fmt->Ashift);                                 \
   401 }
   402 #define ASSEMBLE_RGBA(buf, bpp, fmt, r, g, b, a)                        \
   403 {                                                                       \
   404     switch (bpp) {                                                      \
   405         case 1: {                                                       \
   406             Uint8 _pixel;                                               \
   407                                                                         \
   408             PIXEL_FROM_RGBA(_pixel, fmt, r, g, b, a);                   \
   409             *((Uint8 *)(buf)) = _pixel;                                 \
   410         }                                                               \
   411         break;                                                          \
   412                                                                         \
   413         case 2: {                                                       \
   414             Uint16 _pixel;                                              \
   415                                                                         \
   416             PIXEL_FROM_RGBA(_pixel, fmt, r, g, b, a);                   \
   417             *((Uint16 *)(buf)) = _pixel;                                \
   418         }                                                               \
   419         break;                                                          \
   420                                                                         \
   421         case 3: {                                                       \
   422             if (SDL_BYTEORDER == SDL_LIL_ENDIAN) {                      \
   423                 *((buf)+fmt->Rshift/8) = r;                             \
   424                 *((buf)+fmt->Gshift/8) = g;                             \
   425                 *((buf)+fmt->Bshift/8) = b;                             \
   426             } else {                                                    \
   427                 *((buf)+2-fmt->Rshift/8) = r;                           \
   428                 *((buf)+2-fmt->Gshift/8) = g;                           \
   429                 *((buf)+2-fmt->Bshift/8) = b;                           \
   430             }                                                           \
   431         }                                                               \
   432         break;                                                          \
   433                                                                         \
   434         case 4: {                                                       \
   435             Uint32 _pixel;                                              \
   436                                                                         \
   437             PIXEL_FROM_RGBA(_pixel, fmt, r, g, b, a);                   \
   438             *((Uint32 *)(buf)) = _pixel;                                \
   439         }                                                               \
   440         break;                                                          \
   441     }                                                                   \
   442 }
   443 
   444 /* Blend the RGB values of two pixels with an alpha value */
   445 #define ALPHA_BLEND_RGB(sR, sG, sB, A, dR, dG, dB)                      \
   446 do {                                                                    \
   447     dR = (Uint8)((((int)(sR-dR)*(int)A)/255)+dR);                       \
   448     dG = (Uint8)((((int)(sG-dG)*(int)A)/255)+dG);                       \
   449     dB = (Uint8)((((int)(sB-dB)*(int)A)/255)+dB);                       \
   450 } while(0)
   451 
   452 
   453 /* Blend the RGBA values of two pixels */
   454 #define ALPHA_BLEND_RGBA(sR, sG, sB, sA, dR, dG, dB, dA)                \
   455 do {                                                                    \
   456     dR = (Uint8)((((int)(sR-dR)*(int)sA)/255)+dR);                      \
   457     dG = (Uint8)((((int)(sG-dG)*(int)sA)/255)+dG);                      \
   458     dB = (Uint8)((((int)(sB-dB)*(int)sA)/255)+dB);                      \
   459     dA = (Uint8)((int)sA+dA-((int)sA*dA)/255);                          \
   460 } while(0)
   461 
   462 
   463 /* This is a very useful loop for optimizing blitters */
   464 #if defined(_MSC_VER) && (_MSC_VER == 1300)
   465 /* There's a bug in the Visual C++ 7 optimizer when compiling this code */
   466 #else
   467 #define USE_DUFFS_LOOP
   468 #endif
   469 #ifdef USE_DUFFS_LOOP
   470 
   471 /* 8-times unrolled loop */
   472 #define DUFFS_LOOP8(pixel_copy_increment, width)                        \
   473 { int n = (width+7)/8;                                                  \
   474     switch (width & 7) {                                                \
   475     case 0: do {    pixel_copy_increment; /* fallthrough */             \
   476     case 7:     pixel_copy_increment;     /* fallthrough */             \
   477     case 6:     pixel_copy_increment;     /* fallthrough */             \
   478     case 5:     pixel_copy_increment;     /* fallthrough */             \
   479     case 4:     pixel_copy_increment;     /* fallthrough */             \
   480     case 3:     pixel_copy_increment;     /* fallthrough */             \
   481     case 2:     pixel_copy_increment;     /* fallthrough */             \
   482     case 1:     pixel_copy_increment;     /* fallthrough */             \
   483         } while ( --n > 0 );                                            \
   484     }                                                                   \
   485 }
   486 
   487 /* 4-times unrolled loop */
   488 #define DUFFS_LOOP4(pixel_copy_increment, width)                        \
   489 { int n = (width+3)/4;                                                  \
   490     switch (width & 3) {                                                \
   491     case 0: do {    pixel_copy_increment;   /* fallthrough */           \
   492     case 3:     pixel_copy_increment;       /* fallthrough */           \
   493     case 2:     pixel_copy_increment;       /* fallthrough */           \
   494     case 1:     pixel_copy_increment;       /* fallthrough */           \
   495         } while (--n > 0);                                              \
   496     }                                                                   \
   497 }
   498 
   499 /* Use the 8-times version of the loop by default */
   500 #define DUFFS_LOOP(pixel_copy_increment, width)                         \
   501     DUFFS_LOOP8(pixel_copy_increment, width)
   502 
   503 /* Special version of Duff's device for even more optimization */
   504 #define DUFFS_LOOP_124(pixel_copy_increment1,                           \
   505                        pixel_copy_increment2,                           \
   506                        pixel_copy_increment4, width)                    \
   507 { int n = width;                                                        \
   508     if (n & 1) {                                                        \
   509         pixel_copy_increment1; n -= 1;                                  \
   510     }                                                                   \
   511     if (n & 2) {                                                        \
   512         pixel_copy_increment2; n -= 2;                                  \
   513     }                                                                   \
   514     if (n & 4) {                                                        \
   515         pixel_copy_increment4; n -= 4;                                  \
   516     }                                                                   \
   517     if (n) {                                                            \
   518         n /= 8;                                                         \
   519         do {                                                            \
   520             pixel_copy_increment4;                                      \
   521             pixel_copy_increment4;                                      \
   522         } while (--n > 0);                                              \
   523     }                                                                   \
   524 }
   525 
   526 #else
   527 
   528 /* Don't use Duff's device to unroll loops */
   529 #define DUFFS_LOOP(pixel_copy_increment, width)                         \
   530 { int n;                                                                \
   531     for ( n=width; n > 0; --n ) {                                       \
   532         pixel_copy_increment;                                           \
   533     }                                                                   \
   534 }
   535 #define DUFFS_LOOP8(pixel_copy_increment, width)                        \
   536     DUFFS_LOOP(pixel_copy_increment, width)
   537 #define DUFFS_LOOP4(pixel_copy_increment, width)                        \
   538     DUFFS_LOOP(pixel_copy_increment, width)
   539 #define DUFFS_LOOP_124(pixel_copy_increment1,                           \
   540                        pixel_copy_increment2,                           \
   541                        pixel_copy_increment4, width)                    \
   542     DUFFS_LOOP(pixel_copy_increment1, width)
   543 
   544 #endif /* USE_DUFFS_LOOP */
   545 
   546 /* Prevent Visual C++ 6.0 from printing out stupid warnings */
   547 #if defined(_MSC_VER) && (_MSC_VER >= 600)
   548 #pragma warning(disable: 4550)
   549 #endif
   550 
   551 #endif /* SDL_blit_h_ */
   552 
   553 /* vi: set ts=4 sw=4 expandtab: */