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aligned bitstream support (optional) - patch by ichael Niedermayer <michaelni@gmx.at>

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Originally committed as revision 253 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Michael Niedermayer 23 years ago committed by Arpi
parent 27a3e2c5e0
commit 3587d501a3
2 changed files with 132 additions and 49 deletions
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  1. 38
      libavcodec/common.c
  2. 143
      libavcodec/common.h

38
libavcodec/common.c
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@ -505,41 +505,3 @@ void free_vlc(VLC *vlc)
free(vlc->table_codes);
}
int get_vlc(GetBitContext *s, VLC *vlc)
{
int bit_cnt, code, n, nb_bits, index;
UINT32 bit_buf;
INT16 *table_codes;
INT8 *table_bits;
UINT8 *buf_ptr;
SAVE_BITS(s);
nb_bits = vlc->bits;
table_codes = vlc->table_codes;
table_bits = vlc->table_bits;
for(;;) {
SHOW_BITS(s, index, nb_bits);
code = table_codes[index];
n = table_bits[index];
if (n > 0) {
/* most common case */
FLUSH_BITS(n);
#ifdef STATS
st_bit_counts[st_current_index] += n;
#endif
break;
} else if (n == 0) {
return -1;
} else {
FLUSH_BITS(nb_bits);
#ifdef STATS
st_bit_counts[st_current_index] += nb_bits;
#endif
nb_bits = -n;
table_codes = vlc->table_codes + code;
table_bits = vlc->table_bits + code;
}
}
RESTORE_BITS(s);
return code;
}

143
libavcodec/common.h
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@ -9,6 +9,7 @@
#endif
//#define ALT_BITSTREAM_READER
//#define ALIGNED_BITSTREAM
#ifdef HAVE_AV_CONFIG_H
/* only include the following when compiling package */
@ -200,6 +201,29 @@ typedef struct VLC {
int table_size, table_allocated;
} VLC;
/* used to avoid missaligned exceptions on some archs (alpha, ...) */
#ifdef ARCH_X86
#define unaligned32(a) (*(UINT32*)(a))
#else
#ifdef __GNUC__
static inline uint32_t unaligned32(const void *v) {
struct Unaligned {
uint32_t i;
} __attribute__((packed));
return ((const struct Unaligned *) v)->i;
}
#elif defined(__DECC)
static inline uint32_t unaligned32(const void *v) {
return *(const __unaligned uint32_t *) v;
}
#else
static inline uint32_t unaligned32(const void *v) {
return *(const uint32_t *) v;
}
#endif
#endif //!ARCH_X86
void init_get_bits(GetBitContext *s,
UINT8 *buffer, int buffer_size);
@ -210,8 +234,27 @@ unsigned int show_bits_long(GetBitContext *s, int n);
static inline unsigned int get_bits(GetBitContext *s, int n){
#ifdef ALT_BITSTREAM_READER
#ifdef ALIGNED_BITSTREAM
int index= s->index;
uint32_t result1= be2me_32( ((uint32_t *)s->buffer)[index>>5] );
uint32_t result2= be2me_32( ((uint32_t *)s->buffer)[(index>>5) + 1] );
#ifdef ARCH_X86
asm ("shldl %%cl, %2, %0\n\t"
: "=r" (result1)
: "0" (result1), "r" (result2), "c" (index));
#else
result1<<= (index&0x1F);
result2>>= 32-(index&0x1F);
if((index&0x1F)!=0) result1|= result2;
#endif
result1>>= 32 - n;
index+= n;
s->index= index;
return result1;
#else //ALIGNED_BITSTREAM
int index= s->index;
uint32_t result= be2me_32( *(uint32_t *)(((uint8_t *)s->buffer)+(index>>3)) );
uint32_t result= be2me_32( unaligned32( ((uint8_t *)s->buffer)+(index>>3) ) );
result<<= (index&0x07);
result>>= 32 - n;
@ -219,7 +262,8 @@ static inline unsigned int get_bits(GetBitContext *s, int n){
s->index= index;
return result;
#else
#endif //!ALIGNED_BITSTREAM
#else //ALT_BITSTREAM_READER
if(s->bit_cnt>=n){
/* most common case here */
unsigned int val = s->bit_buf >> (32 - n);
@ -231,16 +275,15 @@ static inline unsigned int get_bits(GetBitContext *s, int n){
return val;
}
return get_bits_long(s,n);
#endif
#endif //!ALT_BITSTREAM_READER
}
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;
uint8_t result= s->buffer[ index>>3 ];
result>>= 7-(index&0x07);
result&=1;
index++;
s->index= index;
@ -266,21 +309,39 @@ static inline unsigned int get_bits1(GetBitContext *s){
static inline unsigned int show_bits(GetBitContext *s, int n)
{
#ifdef ALT_BITSTREAM_READER
#ifdef ALIGNED_BITSTREAM
int index= s->index;
uint32_t result1= be2me_32( ((uint32_t *)s->buffer)[index>>5] );
uint32_t result2= be2me_32( ((uint32_t *)s->buffer)[(index>>5) + 1] );
#ifdef ARCH_X86
asm ("shldl %%cl, %2, %0\n\t"
: "=r" (result1)
: "0" (result1), "r" (result2), "c" (index));
#else
result1<<= (index&0x1F);
result2>>= 32-(index&0x1F);
if((index&0x1F)!=0) result1|= result2;
#endif
result1>>= 32 - n;
return result1;
#else //ALIGNED_BITSTREAM
int index= s->index;
uint32_t result= be2me_32( *(uint32_t *)(((uint8_t *)s->buffer)+(index>>3)) );
uint32_t result= be2me_32( unaligned32( ((uint8_t *)s->buffer)+(index>>3) ) );
result<<= (index&0x07);
result>>= 32 - n;
return result;
#else
#endif //!ALIGNED_BITSTREAM
#else //ALT_BITSTREAM_READER
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
#endif //!ALT_BITSTREAM_READER
}
static inline void skip_bits(GetBitContext *s, int n){
@ -331,7 +392,6 @@ int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size);
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);
@ -381,6 +441,67 @@ int get_vlc(GetBitContext *s, VLC *vlc);
(s)->bit_cnt = bit_cnt;\
}
#endif // !ALT_BITSTREAM_READER
static inline int get_vlc(GetBitContext *s, VLC *vlc)
{
int code, n, nb_bits, index;
INT16 *table_codes;
INT8 *table_bits;
#ifndef ALT_BITSTREAM_READER
int bit_cnt;
UINT32 bit_buf;
UINT8 *buf_ptr;
#endif
SAVE_BITS(s);
nb_bits = vlc->bits;
table_codes = vlc->table_codes;
table_bits = vlc->table_bits;
SHOW_BITS(s, index, nb_bits);
code = table_codes[index];
n = table_bits[index];
if (n > 0) {
/* most common case (90%)*/
FLUSH_BITS(n);
RESTORE_BITS(s);
return code;
} else if (n == 0) {
return -1;
} else {
FLUSH_BITS(nb_bits);
nb_bits = -n;
table_codes = vlc->table_codes + code;
table_bits = vlc->table_bits + code;
}
for(;;) {
SHOW_BITS(s, index, nb_bits);
code = table_codes[index];
n = table_bits[index];
if (n > 0) {
/* most common case */
FLUSH_BITS(n);
#ifdef STATS
st_bit_counts[st_current_index] += n;
#endif
break;
} else if (n == 0) {
return -1;
} else {
FLUSH_BITS(nb_bits);
#ifdef STATS
st_bit_counts[st_current_index] += nb_bits;
#endif
nb_bits = -n;
table_codes = vlc->table_codes + code;
table_bits = vlc->table_bits + code;
}
}
RESTORE_BITS(s);
return code;
}
/* define it to include statistics code (useful only for optimizing
codec efficiency */
//#define STATS

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