Chiebot-Mirror
/
FFmpeg
mirror of https://github.com/FFmpeg/FFmpeg.git
8
0
Fork 0
Code Issues Projects Releases Wiki Activity

x86 branchless cabac decoder

Browse Source 
slightly faster on P3

Originally committed as revision 6608 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Michael Niedermayer 19 years ago
parent 2e1aee80f4
commit ef0090a998
1 changed files with 68 additions and 1 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 69
      libavcodec/cabac.h

69
libavcodec/cabac.h
Unescape View File

@ -31,6 +31,7 @@
#define CABAC_BITS 16
#define CABAC_MASK ((1<<CABAC_BITS)-1)
#define BRANCHLESS_CABAD 1
typedef struct CABACContext{
int low;
@ -374,7 +375,7 @@ static int get_cabac(CABACContext *c, uint8_t * const state){
#define BYTESTART "12+2*66*4+4*65"
#define BYTE "16+2*66*4+4*65"
#define BYTEEND "20+2*66*4+4*65"
#ifndef BRANCHLESS_CABAD
asm volatile(
"movzbl (%1), %%eax \n\t"
"movl "RANGE "(%2), %%ebx \n\t"
@ -446,6 +447,72 @@ static int get_cabac(CABACContext *c, uint8_t * const state){
:"r"(state), "r"(c)
: "%ecx", "%ebx", "%edx", "%esi"
);
#else
asm volatile(
"movzbl (%1), %%eax \n\t"
"movl "RANGE "(%2), %%ebx \n\t"
"movl "RANGE "(%2), %%edx \n\t"
"shrl $23, %%ebx \n\t"
"leal "LPS_RANGE"(%2, %%eax, 4), %%esi \n\t"
"movzbl (%%ebx, %%esi), %%esi \n\t"
"shll $17, %%esi \n\t"
"movl "LOW "(%2), %%ebx \n\t"
//eax:state ebx:low, edx:range, esi:RangeLPS
"subl %%esi, %%edx \n\t"
"movl %%edx, %%ecx \n\t"
"subl %%ebx, %%edx \n\t"
"sarl $31, %%edx \n\t" //lps_mask
"subl %%ecx, %%esi \n\t" //RangeLPS - range
"andl %%edx, %%esi \n\t" //(RangeLPS - range)&lps_mask
"addl %%ecx, %%esi \n\t" //new range
"andl %%edx, %%ecx \n\t"
"subl %%ecx, %%ebx \n\t"
//eax:state ebx:low edx:mask esi:range
"movl $-130, %%ecx \n\t"
"andl %%edx, %%ecx \n\t"
"addl %%eax, %%ecx \n\t"
"xorl %%edx, %%eax \n\t"
"movb "MPS_STATE"(%2, %%eax), %%cl \n\t"
"movb %%cl, (%1) \n\t"
"movl %%esi, %%edx \n\t"
//eax:bit ebx:low edx:range esi:range
"shr $19, %%esi \n\t"
"movb " MANGLE(ff_h264_norm_shift) "(%%esi), %%cl \n\t"
"shll %%cl, %%ebx \n\t"
"shll %%cl, %%edx \n\t"
"test %%bx, %%bx \n\t"
" jnz 1f \n\t"
"movl "BYTE "(%2), %%ecx \n\t"
"movzwl (%%ecx), %%esi \n\t"
"bswap %%esi \n\t"
"shrl $15, %%esi \n\t"
"subl $0xFFFF, %%esi \n\t"
"addl $2, %%ecx \n\t"
"movl %%ecx, "BYTE "(%2) \n\t"
"leal -1(%%ebx), %%ecx \n\t"
"xorl %%ebx, %%ecx \n\t"
"shrl $17, %%ecx \n\t"
"movb " MANGLE(ff_h264_norm_shift) "(%%ecx), %%cl \n\t"
"neg %%cl \n\t"
"add $7, %%cl \n\t"
"shll %%cl , %%esi \n\t"
"addl %%esi, %%ebx \n\t"
"1: \n\t"
"movl %%edx, "RANGE "(%2) \n\t"
"movl %%ebx, "LOW "(%2) \n\t"
"andl $1, %%eax \n\t"
:"=&a"(bit)
:"r"(state), "r"(c)
: "%ecx", "%ebx", "%edx", "%esi"
);
#endif
#else
int s = *state;
int RangeLPS= c->lps_range[s][c->range>>(CABAC_BITS+7)]<<(CABAC_BITS+1);

Write Preview
Loading…
Cancel
Save