New implementation of rgb32tobgr32

The previous implementation segfaulted with MMX enabled when fed an image
smaller than the size of the units the MMX code processed. The new code:
- is faster for MMX, MMX2 and plain C
- processes small images correctly
- is LGPL

Originally committed as revision 23009 to svn://svn.mplayerhq.hu/mplayer/trunk/libswscale

diff --git a/libswscale/rgb2rgb_template.c b/libswscale/rgb2rgb_template.c
index 6489a4d..7147855 100644 (file)
--- a/libswscale/rgb2rgb_template.c
+++ b/libswscale/rgb2rgb_template.c
@@ -1364,49 +1364,66 @@ static inline void RENAME(rgb16to32)(const uint8_t *src, uint8_t *dst, long src_
 
 static inline void RENAME(rgb32tobgr32)(const uint8_t *src, uint8_t *dst, long src_size)
 {
+    uint8_t *d = dst, *s = (uint8_t *) src;
+    const uint8_t *end = s + src_size;
 #ifdef HAVE_MMX
-/* TODO: unroll this loop */
-       asm volatile (
-               "xor %%"REG_a", %%"REG_a"       \n\t"
-               ASMALIGN(4)
-               "1:                             \n\t"
-               PREFETCH" 32(%0, %%"REG_a")     \n\t"
-               "movq (%0, %%"REG_a"), %%mm0    \n\t"
-               "movq %%mm0, %%mm1              \n\t"
-               "movq %%mm0, %%mm2              \n\t"
-               "pslld $16, %%mm0               \n\t"
-               "psrld $16, %%mm1               \n\t"
-               "pand "MANGLE(mask32r)", %%mm0  \n\t"
-               "pand "MANGLE(mask32g)", %%mm2  \n\t"
-               "pand "MANGLE(mask32b)", %%mm1  \n\t"
-               "por %%mm0, %%mm2               \n\t"
-               "por %%mm1, %%mm2               \n\t"
-               MOVNTQ" %%mm2, (%1, %%"REG_a")  \n\t"
-               "add $8, %%"REG_a"              \n\t"
-               "cmp %2, %%"REG_a"              \n\t"
-               " jb 1b                         \n\t"
-               :: "r" (src), "r"(dst), "r" (src_size-7)
-               : "%"REG_a
-       );
-
-       __asm __volatile(SFENCE:::"memory");
-       __asm __volatile(EMMS:::"memory");
-#else
-       unsigned i;
-       unsigned num_pixels = src_size >> 2;
-       for(i=0; i<num_pixels; i++)
-       {
-#ifdef WORDS_BIGENDIAN  
-         dst[4*i + 1] = src[4*i + 3];
-         dst[4*i + 2] = src[4*i + 2];
-         dst[4*i + 3] = src[4*i + 1];
-#else
-         dst[4*i + 0] = src[4*i + 2];
-         dst[4*i + 1] = src[4*i + 1];
-         dst[4*i + 2] = src[4*i + 0];
-#endif
+       __asm __volatile(
+               "       "PREFETCH" (%1)                 \n"
+               "       movq %3, %%mm7                  \n"
+               "       pxor %4, %%mm7                  \n"
+               "       movq %%mm7, %%mm6               \n"
+               "       pxor %5, %%mm7                  \n"
+               "       jmp 2f                          \n"
+                       ASMALIGN(4)
+               "1:                                     \n"
+               "       "PREFETCH" 32(%1)               \n"
+               "       movq (%1), %%mm0                \n"
+               "       movq 8(%1), %%mm1               \n"
+# ifdef HAVE_MMX2
+               "       pshufw $177, %%mm0, %%mm3       \n"
+               "       pshufw $177, %%mm1, %%mm5       \n"
+               "       pand %%mm7, %%mm0               \n"
+               "       pand %%mm6, %%mm3               \n"
+               "       pand %%mm7, %%mm1               \n"
+               "       pand %%mm6, %%mm5               \n"
+               "       por %%mm3, %%mm0                \n"
+               "       por %%mm5, %%mm1                \n"
+# else
+               "       movq %%mm0, %%mm2               \n"
+               "       movq %%mm1, %%mm4               \n"
+               "       pand %%mm7, %%mm0               \n"
+               "       pand %%mm6, %%mm2               \n"
+               "       pand %%mm7, %%mm1               \n"
+               "       pand %%mm6, %%mm4               \n"
+               "       movq %%mm2, %%mm3               \n"
+               "       movq %%mm4, %%mm5               \n"
+               "       pslld $16, %%mm2                \n"
+               "       psrld $16, %%mm3                \n"
+               "       pslld $16, %%mm4                \n"
+               "       psrld $16, %%mm5                \n"
+               "       por %%mm2, %%mm0                \n"
+               "       por %%mm4, %%mm1                \n"
+               "       por %%mm3, %%mm0                \n"
+               "       por %%mm5, %%mm1                \n"
+# endif
+               "       "MOVNTQ" %%mm0, (%0)            \n"
+               "       "MOVNTQ" %%mm1, 8(%0)           \n"
+               "       add $16, %0                     \n"
+               "       add $16, %1                     \n"
+               "2:                                     \n"
+               "       cmp %1, %2                      \n"
+               "       ja 1b                           \n"
+               "       "SFENCE"                        \n"
+               "       "EMMS"                          \n"
+               : "+r"(d), "+r"(s)
+               : "r" (end-15), "m" (mask32b), "m" (mask32r), "m" (mmx_one)
+               : "memory");
+#endif
+       for (; s<end; s+=4, d+=4) {
+               int v = *(uint32_t *)s, g = v & 0xff00;
+               v &= 0xff00ff;
+               *(uint32_t *)d = (v>>16) + g + (v<<16);
        }
-#endif
 }
 
 static inline void RENAME(rgb24tobgr24)(const uint8_t *src, uint8_t *dst, long src_size)