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Optimize 0 0 0-3 search, 45% faster on pentium dual. 

Originally committed as revision 16284 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2008-12-23 00:38:45 +00:00
parent f496ab12e4
commit e08715d391
1 changed files with 17 additions and 0 deletions
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17
libavcodec/h264.c
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@ -1375,9 +1375,26 @@ static const uint8_t *decode_nal(H264Context *h, const uint8_t *src, int *dst_le
for(i=0; i<length; i++)
printf("%2X ", src[i]);
#endif
#ifdef HAVE_FAST_UNALIGNED
# ifdef HAVE_FAST_64BIT
# define RS 7
for(i=0; i+1<length; i+=9){
if(!((~*(uint64_t*)(src+i) & (*(uint64_t*)(src+i) - 0x0100010001000101ULL)) & 0x8000800080008080ULL))
# else
# define RS 3
for(i=0; i+1<length; i+=5){
if(!((~*(uint32_t*)(src+i) & (*(uint32_t*)(src+i) - 0x01000101U)) & 0x80008080U))
# endif
continue;
if(i>0 && !src[i]) i--;
while(src[i]) i++;
#else
# define RS 0
for(i=0; i+1<length; i+=2){
if(src[i]) continue;
if(i>0 && src[i-1]==0) i--;
#endif
if(i+2<length && src[i+1]==0 && src[i+2]<=3){
if(src[i+2]!=3){
/* startcode, so we must be past the end */