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shift CABACContext.range right, this reduces the number of shifts needed in get_cabac() and is slightly faster on P3 (and should be much faster on P4 as the P4 except the more recent variants lacks an integer shifter and so shifts have ~10 times longer latency then simple operations like adds)

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Originally committed as revision 6702 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Michael Niedermayer 19 years ago
parent aa770811a3
commit f24a515931
2 changed files with 77 additions and 52 deletions
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  1. 35
      libavcodec/cabac.c
  2. 94
      libavcodec/cabac.h

35
libavcodec/cabac.c
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@ -51,7 +51,7 @@ static const uint8_t lps_range[64][4]= {
};
uint8_t ff_h264_mlps_state[4*64];
uint8_t ff_h264_lps_range[2*65][4];
uint8_t ff_h264_lps_range[4][2*64];
uint8_t ff_h264_lps_state[2*64];
uint8_t ff_h264_mps_state[2*64];
@ -76,8 +76,8 @@ static const uint8_t lps_state[64]= {
33,33,34,34,35,35,35,36,
36,36,37,37,37,38,38,63,
};
const uint8_t ff_h264_norm_shift[128]= {
#if 0
const uint8_t ff_h264_norm_shift_old[128]= {
7,6,5,5,4,4,4,4,3,3,3,3,3,3,3,3,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
@ -87,6 +87,29 @@ const uint8_t ff_h264_norm_shift[128]= {
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
};
#endif
const uint8_t ff_h264_norm_shift[512]= {
9,8,7,7,6,6,6,6,5,5,5,5,5,5,5,5,
4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
};
/**
*
@ -121,7 +144,7 @@ void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
c->low = (*c->bytestream++)<<10;
#endif
c->low+= ((*c->bytestream++)<<2) + 2;
c->range= 0x1FE<<(CABAC_BITS + 1);
c->range= 0x1FE;
}
void ff_init_cabac_states(CABACContext *c){
@ -129,8 +152,8 @@ void ff_init_cabac_states(CABACContext *c){
for(i=0; i<64; i++){
for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
ff_h264_lps_range[2*i+0][j+4]=
ff_h264_lps_range[2*i+1][j+4]= lps_range[i][j];
ff_h264_lps_range[j][2*i+0]=
ff_h264_lps_range[j][2*i+1]= lps_range[i][j];
}
ff_h264_mlps_state[128+2*i+0]=

94
libavcodec/cabac.h
Unescape View File

@ -48,10 +48,10 @@ typedef struct CABACContext{
}CABACContext;
extern uint8_t ff_h264_mlps_state[4*64];
extern uint8_t ff_h264_lps_range[2*65][4]; ///< rangeTabLPS
extern uint8_t ff_h264_lps_range[4][2*64]; ///< rangeTabLPS
extern uint8_t ff_h264_mps_state[2*64]; ///< transIdxMPS
extern uint8_t ff_h264_lps_state[2*64]; ///< transIdxLPS
extern const uint8_t ff_h264_norm_shift[128];
extern const uint8_t ff_h264_norm_shift[512];
void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size);
@ -85,7 +85,7 @@ static inline void renorm_cabac_encoder(CABACContext *c){
}
static void put_cabac(CABACContext *c, uint8_t * const state, int bit){
int RangeLPS= ff_h264_lps_range[*state][c->range>>6];
int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state];
if(bit == ((*state)&1)){
c->range -= RangeLPS;
@ -268,7 +268,7 @@ static void refill2(CABACContext *c){
int i, x;
x= c->low ^ (c->low-1);
i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS+1)];
i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)];
x= -CABAC_MASK;
@ -283,7 +283,7 @@ static void refill2(CABACContext *c){
}
static inline void renorm_cabac_decoder(CABACContext *c){
while(c->range < (0x200 << CABAC_BITS)){
while(c->range < 0x100){
c->range+= c->range;
c->low+= c->low;
if(!(c->low & CABAC_MASK))
@ -297,7 +297,7 @@ static inline void renorm_cabac_decoder_once(CABACContext *c){
#if 0
//P3:683 athlon:475
asm(
"lea -0x2000000(%0), %2 \n\t"
"lea -0x100(%0), %2 \n\t"
"shr $31, %2 \n\t" //FIXME 31->63 for x86-64
"shl %%cl, %0 \n\t"
"shl %%cl, %1 \n\t"
@ -306,7 +306,7 @@ static inline void renorm_cabac_decoder_once(CABACContext *c){
#elif 0
//P3:680 athlon:474
asm(
"cmp $0x2000000, %0 \n\t"
"cmp $0x100, %0 \n\t"
"setb %%cl \n\t" //FIXME 31->63 for x86-64
"shl %%cl, %0 \n\t"
"shl %%cl, %1 \n\t"
@ -316,7 +316,7 @@ static inline void renorm_cabac_decoder_once(CABACContext *c){
int temp2;
//P3:665 athlon:517
asm(
"lea -0x2000000(%0), %%eax \n\t"
"lea -0x100(%0), %%eax \n\t"
"cdq \n\t"
"mov %0, %%eax \n\t"
"and %%edx, %0 \n\t"
@ -329,7 +329,7 @@ static inline void renorm_cabac_decoder_once(CABACContext *c){
int temp2;
//P3:673 athlon:509
asm(
"cmp $0x2000000, %0 \n\t"
"cmp $0x100, %0 \n\t"
"sbb %%edx, %%edx \n\t"
"mov %0, %%eax \n\t"
"and %%edx, %0 \n\t"
@ -342,7 +342,7 @@ static inline void renorm_cabac_decoder_once(CABACContext *c){
int temp2;
//P3:677 athlon:511
asm(
"cmp $0x2000000, %0 \n\t"
"cmp $0x100, %0 \n\t"
"lea (%0, %0), %%eax \n\t"
"lea (%1, %1), %%edx \n\t"
"cmovb %%eax, %0 \n\t"
@ -352,7 +352,7 @@ static inline void renorm_cabac_decoder_once(CABACContext *c){
#endif
#else
//P3:675 athlon:476
int shift= (uint32_t)(c->range - (0x200 << CABAC_BITS))>>31;
int shift= (uint32_t)(c->range - 0x100)>>31;
c->range<<= shift;
c->low <<= shift;
#endif
@ -375,24 +375,25 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
"movzbl (%1), %%eax \n\t"
"movl "RANGE "(%2), %%ebx \n\t"
"movl "RANGE "(%2), %%edx \n\t"
"shrl $23, %%ebx \n\t"
"movzbl "MANGLE(ff_h264_lps_range)"(%%ebx, %%eax, 4), %%esi\n\t"
"shll $17, %%esi \n\t"
"andl $0xC0, %%ebx \n\t"
"movzbl "MANGLE(ff_h264_lps_range)"(%%eax, %%ebx, 2), %%esi\n\t"
"movl "LOW "(%2), %%ebx \n\t"
//eax:state ebx:low, edx:range, esi:RangeLPS
"subl %%esi, %%edx \n\t"
"cmpl %%edx, %%ebx \n\t"
"movl %%edx, %%ecx \n\t"
"shll $17, %%ecx \n\t"
"cmpl %%ecx, %%ebx \n\t"
" ja 1f \n\t"
#if 1
//athlon:4067 P3:4110
"lea -0x2000000(%%edx), %%ecx \n\t"
"lea -0x100(%%edx), %%ecx \n\t"
"shr $31, %%ecx \n\t"
"shl %%cl, %%edx \n\t"
"shl %%cl, %%ebx \n\t"
#else
//athlon:4057 P3:4130
"cmp $0x2000000, %%edx \n\t" //FIXME avoidable
"cmp $0x100, %%edx \n\t" //FIXME avoidable
"setb %%cl \n\t"
"shl %%cl, %%edx \n\t"
"shl %%cl, %%ebx \n\t"
@ -413,14 +414,13 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
"jmp 2f \n\t"
"1: \n\t"
//eax:state ebx:low, edx:range, esi:RangeLPS
"subl %%edx, %%ebx \n\t"
"subl %%ecx, %%ebx \n\t"
"movl %%esi, %%edx \n\t"
"shr $19, %%esi \n\t"
"movzbl "MANGLE(ff_h264_lps_state)"(%%eax), %%ecx \n\t"
"movb %%cl, (%1) \n\t"
"movzbl " MANGLE(ff_h264_norm_shift) "(%%esi), %%ecx \n\t"
"shll %%cl, %%ebx \n\t"
"shll %%cl, %%edx \n\t"
"movzbl "MANGLE(ff_h264_lps_state)"(%%eax), %%ecx \n\t"
"movb %%cl, (%1) \n\t"
"addl $1, %%eax \n\t"
"test %%bx, %%bx \n\t"
" jnz 2f \n\t"
@ -435,7 +435,7 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
"leal -1(%%ebx), %%ecx \n\t"
"xorl %%ebx, %%ecx \n\t"
"shrl $17, %%ecx \n\t"
"shrl $15, %%ecx \n\t"
"movzbl " MANGLE(ff_h264_norm_shift) "(%%ecx), %%ecx \n\t"
"neg %%ecx \n\t"
"add $7, %%ecx \n\t"
@ -455,20 +455,22 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
"movzbl (%1), %%eax \n\t"
"movl "RANGE "(%2), %%ebx \n\t"
"movl "RANGE "(%2), %%edx \n\t"
"shrl $23, %%ebx \n\t"
"movzbl "MANGLE(ff_h264_lps_range)"(%%ebx, %%eax, 4), %%esi\n\t"
"shll $17, %%esi \n\t"
"andl $0xC0, %%ebx \n\t"
"movzbl "MANGLE(ff_h264_lps_range)"(%%eax, %%ebx, 2), %%esi\n\t"
"movl "LOW "(%2), %%ebx \n\t"
//eax:state ebx:low, edx:range, esi:RangeLPS
"subl %%esi, %%edx \n\t"
#ifdef CMOV_IS_FAST //FIXME actually define this somewhere
#ifdef CMOV_IS_FAST
"movl %%edx, %%ecx \n\t"
"shl $17, %%edx \n\t"
"cmpl %%ebx, %%edx \n\t"
"cmova %%edx, %%esi \n\t"
"cmova %%ecx, %%esi \n\t"
"sbbl %%ecx, %%ecx \n\t"
"andl %%ecx, %%edx \n\t"
"subl %%edx, %%ebx \n\t"
"xorl %%ecx, %%eax \n\t"
#else /* CMOV_IS_FAST */
FIXTHIS
"movl %%edx, %%ecx \n\t"
"subl %%ebx, %%edx \n\t"
"sarl $31, %%edx \n\t" //lps_mask
@ -481,16 +483,14 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
#endif /* CMOV_IS_FAST */
//eax:state ebx:low edx:mask esi:range
"movzbl "MANGLE(ff_h264_mlps_state)"+128(%%eax), %%ecx \n\t"
"movb %%cl, (%1) \n\t"
"movl %%esi, %%edx \n\t"
//eax:bit ebx:low edx:range esi:range
//eax:bit ebx:low esi:range
"shr $19, %%esi \n\t"
"movzbl " MANGLE(ff_h264_norm_shift) "(%%esi), %%ecx \n\t"
"shll %%cl, %%edx \n\t"
"movl %%edx, "RANGE "(%2) \n\t"
"shll %%cl, %%esi \n\t"
"movzbl "MANGLE(ff_h264_mlps_state)"+128(%%eax), %%edx \n\t"
"movb %%dl, (%1) \n\t"
"movl %%esi, "RANGE "(%2) \n\t"
"shll %%cl, %%ebx \n\t"
"movl %%ebx, "LOW "(%2) \n\t"
"test %%bx, %%bx \n\t"
@ -506,7 +506,7 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
"leal -1(%%ebx), %%ecx \n\t"
"xorl %%ebx, %%ecx \n\t"
"shrl $17, %%ecx \n\t"
"shrl $15, %%ecx \n\t"
"movzbl " MANGLE(ff_h264_norm_shift) "(%%ecx), %%ecx \n\t"
"neg %%ecx \n\t"
"add $7, %%ecx \n\t"
@ -523,18 +523,18 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
#endif /* BRANCHLESS_CABAC_DECODER */
#else /* ARCH_X86 */
int s = *state;
int RangeLPS= ff_h264_lps_range[s][c->range>>(CABAC_BITS+7)]<<(CABAC_BITS+1);
int RangeLPS= ff_h264_lps_range[0][2*(c->range&0xC0) + s];
int bit, lps_mask attribute_unused;
c->range -= RangeLPS;
#ifndef BRANCHLESS_CABAC_DECODER
if(c->low < c->range){
if(c->low < (c->range<<17)){
bit= s&1;
*state= ff_h264_mps_state[s];
renorm_cabac_decoder_once(c);
}else{
bit= ff_h264_norm_shift[RangeLPS>>19];
c->low -= c->range;
bit= ff_h264_norm_shift[RangeLPS];
c->low -= (c->range<<17);
*state= ff_h264_lps_state[s];
c->range = RangeLPS<<bit;
c->low <<= bit;
@ -545,16 +545,16 @@ static int always_inline get_cabac_inline(CABACContext *c, uint8_t * const state
}
}
#else /* BRANCHLESS_CABAC_DECODER */
lps_mask= (c->range - c->low)>>31;
lps_mask= ((c->range<<17) - c->low)>>31;
c->low -= c->range & lps_mask;
c->low -= (c->range<<17) & lps_mask;
c->range += (RangeLPS - c->range) & lps_mask;
s^=lps_mask;
*state= (ff_h264_mlps_state+128)[s];
bit= s&1;
lps_mask= ff_h264_norm_shift[c->range>>(CABAC_BITS+3)];
lps_mask= ff_h264_norm_shift[c->range];
c->range<<= lps_mask;
c->low <<= lps_mask;
if(!(c->low & CABAC_MASK))
@ -573,15 +573,17 @@ static int get_cabac(CABACContext *c, uint8_t * const state){
}
static int get_cabac_bypass(CABACContext *c){
int range;
c->low += c->low;
if(!(c->low & CABAC_MASK))
refill(c);
if(c->low < c->range){
range= c->range<<17;
if(c->low < range){
return 0;
}else{
c->low -= c->range;
c->low -= range;
return 1;
}
}
@ -591,8 +593,8 @@ static int get_cabac_bypass(CABACContext *c){
* @return the number of bytes read or 0 if no end
*/
static int get_cabac_terminate(CABACContext *c){
c->range -= 4<<CABAC_BITS;
if(c->low < c->range){
c->range -= 2;
if(c->low < c->range<<17){
renorm_cabac_decoder_once(c);
return 0;
}else{

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