slightly faster rgb32tobgr32; avoid one add and one cmp

Originally committed as revision 23012 to svn://svn.mplayerhq.hu/mplayer/trunk/libswscale

diff --git a/libswscale/rgb2rgb_template.c b/libswscale/rgb2rgb_template.c
index 7147855..2053a6e 100644 (file)
--- a/libswscale/rgb2rgb_template.c
+++ b/libswscale/rgb2rgb_template.c
@@ -1364,21 +1364,22 @@ 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;
+       long idx = 15 - src_size;
+       uint8_t *s = (uint8_t *) src-idx, *d = dst-idx;
 #ifdef HAVE_MMX
        __asm __volatile(
-               "       "PREFETCH" (%1)                 \n"
+               "       test %0, %0                     \n"
+               "       jns 2f                          \n"
+               "       "PREFETCH" (%1, %0)             \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"
+               "       "PREFETCH" 32(%1, %0)           \n"
+               "       movq (%1, %0), %%mm0            \n"
+               "       movq 8(%1, %0), %%mm1           \n"
 # ifdef HAVE_MMX2
                "       pshufw $177, %%mm0, %%mm3       \n"
                "       pshufw $177, %%mm1, %%mm5       \n"
@@ -1406,23 +1407,21 @@ static inline void RENAME(rgb32tobgr32)(const uint8_t *src, uint8_t *dst, long s
                "       por %%mm3, %%mm0                \n"
                "       por %%mm5, %%mm1                \n"
 # endif
-               "       "MOVNTQ" %%mm0, (%0)            \n"
-               "       "MOVNTQ" %%mm1, 8(%0)           \n"
+               "       "MOVNTQ" %%mm0, (%2, %0)        \n"
+               "       "MOVNTQ" %%mm1, 8(%2, %0)       \n"
                "       add $16, %0                     \n"
-               "       add $16, %1                     \n"
-               "2:                                     \n"
-               "       cmp %1, %2                      \n"
-               "       ja 1b                           \n"
+               "       js 1b                           \n"
                "       "SFENCE"                        \n"
                "       "EMMS"                          \n"
-               : "+r"(d), "+r"(s)
-               : "r" (end-15), "m" (mask32b), "m" (mask32r), "m" (mmx_one)
+               "2:                                     \n"
+               : "+&r"(idx)
+               : "r" (s), "r" (d), "m" (mask32b), "m" (mask32r), "m" (mmx_one)
                : "memory");
 #endif
-       for (; s<end; s+=4, d+=4) {
-               int v = *(uint32_t *)s, g = v & 0xff00;
+       for (; idx<15; idx+=4) {
+               register int v = *(uint32_t *)&s[idx], g = v & 0xff00;
                v &= 0xff00ff;
-               *(uint32_t *)d = (v>>16) + g + (v<<16);
+               *(uint32_t *)&d[idx] = (v>>16) + g + (v<<16);
        }
 }