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ffmpeg.wasm-core
Commit 27a3e2c5 authored by Michael Niedermayer's avatar Michael Niedermayer
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another bitstream reader code (faster on intel cpus) - patch by Michael... 

another bitstream reader code (faster on intel cpus) - patch by Michael Niedermayer <michaelni@gmx.at>

Originally committed as revision 252 to svn://svn.ffmpeg.org/ffmpeg/trunk
parent bff6ecaa
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Showing with 94 additions and 1 deletion
libavcodec/common.c
View file @ 27a3e2c5
......@@ -15,6 +15,8 @@
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* alternative bitstream reader by Michael Niedermayer <michaelni@gmx.at>
*/
#include "common.h"
#include <math.h>
......@@ -174,6 +176,10 @@ void jflush_put_bits(PutBitContext *s)
void init_get_bits(GetBitContext *s,
UINT8 *buffer, int buffer_size)
{
#ifdef ALT_BITSTREAM_READER
s->index=0;
s->buffer= buffer;
#else
s->buf = buffer;
s->buf_ptr = buffer;
s->buf_end = buffer + buffer_size;
......@@ -184,8 +190,10 @@ void init_get_bits(GetBitContext *s,
s->bit_buf |= (*s->buf_ptr++ << (24 - s->bit_cnt));
s->bit_cnt += 8;
}
#endif
}
#ifndef ALT_BITSTREAM_READER
/* n must be >= 1 and <= 32 */
/* also true: n > s->bit_cnt */
unsigned int get_bits_long(GetBitContext *s, int n)
......@@ -241,15 +249,22 @@ unsigned int get_bits_long(GetBitContext *s, int n)
s->bit_cnt = bit_cnt;
return val;
}
#endif
void align_get_bits(GetBitContext *s)
{
#ifdef ALT_BITSTREAM_READER
s->index= (s->index + 7) & (~7);
#else
int n;
n = s->bit_cnt & 7;
if (n > 0) {
get_bits(s, n);
}
#endif
}
#ifndef ALT_BITSTREAM_READER
/* This function is identical to get_bits_long(), the */
/* only diference is that it doesn't touch the buffer */
/* it is usefull to see the buffer. */
......@@ -296,6 +311,7 @@ unsigned int show_bits_long(GetBitContext *s, int n)
return val;
}
#endif
/* VLC decoding */
......
libavcodec/common.h
View file @ 27a3e2c5
......@@ -8,6 +8,8 @@
#define CONFIG_WIN32
#endif
//#define ALT_BITSTREAM_READER
#ifdef HAVE_AV_CONFIG_H
/* only include the following when compiling package */
#include "../config.h"
......@@ -124,6 +126,7 @@ typedef signed long long INT64;
#endif /* !CONFIG_WIN32 */
/* debug stuff */
#ifdef HAVE_AV_CONFIG_H
......@@ -180,9 +183,14 @@ void jflush_put_bits(PutBitContext *s);
/* bit input */
typedef struct GetBitContext {
#ifdef ALT_BITSTREAM_READER
int index;
UINT8 *buffer;
#else
UINT32 bit_buf;
int bit_cnt;
UINT8 *buf, *buf_ptr, *buf_end;
#endif
} GetBitContext;
typedef struct VLC {
......@@ -195,10 +203,23 @@ typedef struct VLC {
void init_get_bits(GetBitContext *s,
UINT8 *buffer, int buffer_size);
#ifndef ALT_BITSTREAM_READER
unsigned int get_bits_long(GetBitContext *s, int n);
unsigned int show_bits_long(GetBitContext *s, int n);
#endif
static inline unsigned int get_bits(GetBitContext *s, int n){
#ifdef ALT_BITSTREAM_READER
int index= s->index;
uint32_t result= be2me_32( *(uint32_t *)(((uint8_t *)s->buffer)+(index>>3)) );
result<<= (index&0x07);
result>>= 32 - n;
index+= n;
s->index= index;
return result;
#else
if(s->bit_cnt>=n){
/* most common case here */
unsigned int val = s->bit_buf >> (32 - n);
......@@ -210,9 +231,21 @@ static inline unsigned int get_bits(GetBitContext *s, int n){
return val;
}
return get_bits_long(s,n);
#endif
}
static inline unsigned int get_bits1(GetBitContext *s){
#ifdef ALT_BITSTREAM_READER
int index= s->index;
uint32_t result= be2me_32( *(uint32_t *)(((uint8_t *)s->buffer)+(index>>3)) );
result<<= (index&0x07);
result>>= 32 - 1;
index++;
s->index= index;
return result;
#else
if(s->bit_cnt>0){
/* most common case here */
unsigned int val = s->bit_buf >> 31;
......@@ -224,6 +257,7 @@ static inline unsigned int get_bits1(GetBitContext *s){
return val;
}
return get_bits_long(s,1);
#endif
}
/* This function is identical to get_bits(), the only */
......@@ -231,15 +265,28 @@ static inline unsigned int get_bits1(GetBitContext *s){
/* it is usefull to see the buffer. */
static inline unsigned int show_bits(GetBitContext *s, int n)
{
#ifdef ALT_BITSTREAM_READER
int index= s->index;
uint32_t result= be2me_32( *(uint32_t *)(((uint8_t *)s->buffer)+(index>>3)) );
result<<= (index&0x07);
result>>= 32 - n;
return result;
#else
if(s->bit_cnt>=n) {
/* most common case here */
unsigned int val = s->bit_buf >> (32 - n);
return val;
}
return show_bits_long(s,n);
#endif
}
static inline void skip_bits(GetBitContext *s, int n){
#ifdef ALT_BITSTREAM_READER
s->index+= n;
#else
if(s->bit_cnt>=n){
/* most common case here */
s->bit_buf <<= n;
......@@ -250,9 +297,13 @@ static inline void skip_bits(GetBitContext *s, int n){
} else {
get_bits_long(s,n);
}
#endif
}
static inline void skip_bits1(GetBitContext *s){
#ifdef ALT_BITSTREAM_READER
s->index++;
#else
if(s->bit_cnt>0){
/* most common case here */
s->bit_buf <<= 1;
......@@ -263,11 +314,16 @@ static inline void skip_bits1(GetBitContext *s){
} else {
get_bits_long(s,1);
}
#endif
}
static inline int get_bits_count(GetBitContext *s)
{
#ifdef ALT_BITSTREAM_READER
return s->index;
#else
return (s->buf_ptr - s->buf) * 8 - s->bit_cnt;
#endif
}
void align_get_bits(GetBitContext *s);
......@@ -277,6 +333,13 @@ int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
void free_vlc(VLC *vlc);
int get_vlc(GetBitContext *s, VLC *vlc);
#ifdef ALT_BITSTREAM_READER
#define SHOW_BITS(s, val, n) val= show_bits(s, n);
#define FLUSH_BITS(n) skip_bits(s, n);
#define SAVE_BITS(s) ;
#define RESTORE_BITS(s) ;
#else
/* macro to go faster */
/* n must be <= 24 */
/* XXX: optimize buffer end test */
......@@ -317,7 +380,7 @@ int get_vlc(GetBitContext *s, VLC *vlc);
(s)->bit_buf = bit_buf;\
(s)->bit_cnt = bit_cnt;\
}
#endif // !ALT_BITSTREAM_READER
/* define it to include statistics code (useful only for optimizing
codec efficiency */
//#define STATS
......
libavcodec/mpegaudiodec.c
View file @ 27a3e2c5
......@@ -1371,7 +1371,11 @@ static void seek_to_maindata(MPADecodeContext *s, long backstep)
UINT8 *ptr;
/* compute current position in stream */
#ifdef ALT_BITSTREAM_READER
ptr = s->gb.buffer + (s->gb.index>>3);
#else
ptr = s->gb.buf_ptr - (s->gb.bit_cnt >> 3);
#endif
/* copy old data before current one */
ptr -= backstep;
memcpy(ptr, s->inbuf1[s->inbuf_index ^ 1] +
......@@ -1528,15 +1532,25 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
/* some encoders generate an incorrect size for this
part. We must go back into the data */
s_index -= 4;
#ifdef ALT_BITSTREAM_READER
s->gb.buffer = last_buf_ptr;
s->gb.index = last_bit_cnt;
#else
s->gb.buf_ptr = last_buf_ptr;
s->gb.bit_buf = last_bit_buf;
s->gb.bit_cnt = last_bit_cnt;
#endif
}
break;
}
#ifdef ALT_BITSTREAM_READER
last_buf_ptr = s->gb.buffer;
last_bit_cnt = s->gb.index;
#else
last_buf_ptr = s->gb.buf_ptr;
last_bit_buf = s->gb.bit_buf;
last_bit_cnt = s->gb.bit_cnt;
#endif
code = get_vlc(&s->gb, vlc);
dprintf("t=%d code=%d\n", g->count1table_select, code);
......
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