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optimization 

Originally committed as revision 3639 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2004-10-26 03:12:21 +00:00
parent 9297ddd32e
commit ec7eb8966c
2 changed files with 108 additions and 43 deletions
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35
libavcodec/cabac.c
View File

@ -69,6 +69,25 @@ const uint8_t ff_h264_lps_state[64]= {
36,36,37,37,37,38,38,63,
};
const uint8_t ff_h264_norm_shift[256]= {
8,7,6,6,5,5,5,5,4,4,4,4,4,4,4,4,
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,
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,
};
/**
*
* @param buf_size size of buf in bits
@ -95,10 +114,14 @@ void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
c->bytestream= buf;
c->bytestream_end= buf + buf_size;
c->low= *c->bytestream++;
c->low= (c->low<<9) + ((*c->bytestream++)<<1);
c->range= 0x1FE00;
c->bits_left= 7;
#if CABAC_BITS == 16
c->low = (*c->bytestream++)<<18;
c->low+= (*c->bytestream++)<<10;
#else
c->low = (*c->bytestream++)<<10;
#endif
c->low+= ((*c->bytestream++)<<2) + 2;
c->range= 0x1FE<<(CABAC_BITS + 1);
}
void ff_init_cabac_states(CABACContext *c, uint8_t const (*lps_range)[4],
@ -107,8 +130,8 @@ void ff_init_cabac_states(CABACContext *c, uint8_t const (*lps_range)[4],
for(i=0; i<state_count; i++){
for(j=0; j<4; j++){ //FIXME check if this is worth the 1 shift we save
c->lps_range[2*i+0][j]=
c->lps_range[2*i+1][j]= lps_range[i][j];
c->lps_range[2*i+0][j+4]=
c->lps_range[2*i+1][j+4]= lps_range[i][j];
}
c->mps_state[2*i+0]= 2*mps_state[i];

116
libavcodec/cabac.h
View File

@ -27,6 +27,9 @@
#undef NDEBUG
#include <assert.h>
#define CABAC_BITS 8
#define CABAC_MASK ((1<<CABAC_BITS)-1)
typedef struct CABACContext{
int low;
int range;
@ -34,19 +37,20 @@ typedef struct CABACContext{
#ifdef STRICT_LIMITS
int symCount;
#endif
uint8_t lps_range[2*64][4]; ///< rangeTabLPS
uint8_t lps_range[2*65][4]; ///< rangeTabLPS
uint8_t lps_state[2*64]; ///< transIdxLPS
uint8_t mps_state[2*64]; ///< transIdxMPS
const uint8_t *bytestream_start;
const uint8_t *bytestream;
const uint8_t *bytestream_end;
int bits_left; ///<
PutBitContext pb;
}CABACContext;
extern const uint8_t ff_h264_lps_range[64][4];
extern const uint8_t ff_h264_mps_state[64];
extern const uint8_t ff_h264_lps_state[64];
extern const uint8_t ff_h264_norm_shift[256];
void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size);
void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size);
@ -80,7 +84,7 @@ static inline void renorm_cabac_encoder(CABACContext *c){
}
static inline void put_cabac(CABACContext *c, uint8_t * const state, int bit){
int RangeLPS= c->lps_range[*state][((c->range)>>6)&3];
int RangeLPS= c->lps_range[*state][c->range>>6];
if(bit == ((*state)&1)){
c->range -= RangeLPS;
@ -249,63 +253,101 @@ static inline void put_cabac_ueg(CABACContext *c, uint8_t * state, int v, int ma
}
}
static void refill(CABACContext *c){
if(c->bytestream < c->bytestream_end)
#if CABAC_BITS == 16
c->low+= ((c->bytestream[0]<<9) + (c->bytestream[1])<<1);
#else
c->low+= c->bytestream[0]<<1;
#endif
c->low -= CABAC_MASK;
c->bytestream+= CABAC_BITS/8;
}
static void refill2(CABACContext *c){
int i, x;
x= c->low ^ (c->low-1);
i= 8 - ff_h264_norm_shift[x>>(CABAC_BITS+1)];
x= -CABAC_MASK;
if(c->bytestream < c->bytestream_end)
#if CABAC_BITS == 16
x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
#else
x+= c->bytestream[0]<<1;
#endif
c->low += x<<i;
c->bytestream+= CABAC_BITS/8;
}
static inline void renorm_cabac_decoder(CABACContext *c){
while(c->range < 0x10000){
while(c->range < (0x200 << CABAC_BITS)){
c->range+= c->range;
c->low+= c->low;
if(--c->bits_left == 0){
if(c->bytestream < c->bytestream_end)
c->low+= *c->bytestream;
c->bytestream++;
c->bits_left= 8;
}
if(!(c->low & CABAC_MASK))
refill(c);
}
}
static inline void renorm_cabac_decoder_once(CABACContext *c){
int mask= (c->range - (0x200 << CABAC_BITS))>>31;
c->range+= c->range&mask;
c->low += c->low &mask;
if(!(c->low & CABAC_MASK))
refill(c);
}
static inline int get_cabac(CABACContext *c, uint8_t * const state){
int RangeLPS= c->lps_range[*state][((c->range)>>14)&3]<<8;
int bit;
int RangeLPS= c->lps_range[*state][c->range>>(CABAC_BITS+7)]<<(CABAC_BITS+1);
int bit, lps_mask;
c->range -= RangeLPS;
#if 1
if(c->low < c->range){
bit= (*state)&1;
*state= c->mps_state[*state];
renorm_cabac_decoder_once(c);
}else{
// int shift= ff_h264_norm_shift[RangeLPS>>17];
bit= ((*state)&1)^1;
c->low -= c->range;
c->range = RangeLPS;
*state= c->lps_state[*state];
}
renorm_cabac_decoder(c);
return bit;
}
static inline int get_cabac_static(CABACContext *c, int RangeLPS){
int bit;
c->range -= RangeLPS;
if(c->low < c->range){
bit= 0;
}else{
bit= 1;
c->low -= c->range;
c->range = RangeLPS;
renorm_cabac_decoder(c);
/* c->range = RangeLPS<<shift;
c->low <<= shift;
if(!(c->low & 0xFFFF)){
refill2(c);
}*/
}
renorm_cabac_decoder(c);
#else
lps_mask= (c->range - c->low)>>31;
c->low -= c->range & lps_mask;
c->range += (RangeLPS - c->range) & lps_mask;
bit= ((*state)^lps_mask)&1;
*state= c->mps_state[(*state) - (128&lps_mask)];
lps_mask= ff_h264_norm_shift[c->range>>(CABAC_BITS+2)];
c->range<<= lps_mask;
c->low <<= lps_mask;
if(!(c->low & CABAC_MASK))
refill2(c);
#endif
return bit;
}
static inline int get_cabac_bypass(CABACContext *c){
c->low += c->low;
if(--c->bits_left == 0){
if(c->bytestream < c->bytestream_end)
c->low+= *c->bytestream;
c->bytestream++;
c->bits_left= 8;
}
if(!(c->low & CABAC_MASK))
refill(c);
if(c->low < c->range){
return 0;
@ -320,9 +362,9 @@ static inline int get_cabac_bypass(CABACContext *c){
* @return the number of bytes read or 0 if no end
*/
static inline int get_cabac_terminate(CABACContext *c){
c->range -= 2<<8;
c->range -= 4<<CABAC_BITS;
if(c->low < c->range){
renorm_cabac_decoder(c);
renorm_cabac_decoder_once(c);
return 0;
}else{
return c->bytestream - c->bytestream_start;