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LE bitstream reader based upon a patch by (Balatoni Denes <dbalatoni programozo hu)

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Originally committed as revision 4215 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2005-05-11 01:46:13 +00:00
parent 0de1318a29
commit cea27ac714
2 changed files with 45 additions and 9 deletions
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20
libavcodec/bitstream.c
View File

@ -132,14 +132,14 @@ static int build_table(VLC *vlc, int table_nb_bits,
int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
uint32_t code_prefix, int n_prefix, int use_static)
uint32_t code_prefix, int n_prefix, int flags)
{
int i, j, k, n, table_size, table_index, nb, n1, index;
int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2;
uint32_t code;
VLC_TYPE (*table)[2];
table_size = 1 << table_nb_bits;
table_index = alloc_table(vlc, table_size, use_static);
table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_STATIC);
#ifdef DEBUG_VLC
printf("new table index=%d size=%d code_prefix=%x n=%d\n",
table_index, table_size, code_prefix, n_prefix);
@ -165,12 +165,18 @@ static int build_table(VLC *vlc, int table_nb_bits,
#endif
/* if code matches the prefix, it is in the table */
n -= n_prefix;
if (n > 0 && (code >> n) == code_prefix) {
if(flags & INIT_VLC_LE)
code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (1 << n_prefix)-1);
else
code_prefix2= code >> n;
if (n > 0 && code_prefix2 == code_prefix) {
if (n <= table_nb_bits) {
/* no need to add another table */
j = (code << (table_nb_bits - n)) & (table_size - 1);
nb = 1 << (table_nb_bits - n);
for(k=0;k<nb;k++) {
if(flags & INIT_VLC_LE)
j = (code >> n_prefix) + (k<<n);
#ifdef DEBUG_VLC
av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n",
j, i, n);
@ -185,7 +191,7 @@ static int build_table(VLC *vlc, int table_nb_bits,
}
} else {
n -= table_nb_bits;
j = (code >> n) & ((1 << table_nb_bits) - 1);
j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
#ifdef DEBUG_VLC
printf("%4x: n=%d (subtable)\n",
j, n);
@ -211,8 +217,8 @@ static int build_table(VLC *vlc, int table_nb_bits,
index = build_table(vlc, n, nb_codes,
bits, bits_wrap, bits_size,
codes, codes_wrap, codes_size,
(code_prefix << table_nb_bits) | i,
n_prefix + table_nb_bits, use_static);
(flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
n_prefix + table_nb_bits, flags);
if (index < 0)
return -1;
/* note: realloc has been done, so reload tables */

34
libavcodec/bitstream.h
View File

@ -368,6 +368,16 @@ static inline int unaligned32_be(const void *v)
#endif
}
static inline int unaligned32_le(const void *v)
{
#ifdef CONFIG_ALIGN
const uint8_t *p=v;
return (((p[3]<<8) | p[2])<<16) | (p[1]<<8) | (p[0]);
#else
return le2me_32( unaligned32(v)); //original
#endif
}
#ifdef ALT_BITSTREAM_READER
# define MIN_CACHE_BITS 25
@ -378,11 +388,19 @@ static inline int unaligned32_be(const void *v)
# define CLOSE_READER(name, gb)\
(gb)->index= name##_index;\
# ifdef ALT_BITSTREAM_READER_LE
# define UPDATE_CACHE(name, gb)\
name##_cache= unaligned32_le( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
# define SKIP_CACHE(name, gb, num)\
name##_cache >>= (num);
# else
# define UPDATE_CACHE(name, gb)\
name##_cache= unaligned32_be( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
# define SKIP_CACHE(name, gb, num)\
name##_cache <<= (num);\
name##_cache <<= (num);
# endif
// FIXME name?
# define SKIP_COUNTER(name, gb, num)\
@ -397,8 +415,13 @@ static inline int unaligned32_be(const void *v)
# define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
# define LAST_SKIP_CACHE(name, gb, num) ;
# ifdef ALT_BITSTREAM_READER_LE
# define SHOW_UBITS(name, gb, num)\
((name##_cache) & (NEG_USR32(0xffffffff,num)))
# else
# define SHOW_UBITS(name, gb, num)\
NEG_USR32(name##_cache, num)
# endif
# define SHOW_SBITS(name, gb, num)\
NEG_SSR32(name##_cache, num)
@ -616,8 +639,13 @@ static inline unsigned int get_bits1(GetBitContext *s){
#ifdef ALT_BITSTREAM_READER
int index= s->index;
uint8_t result= s->buffer[ index>>3 ];
#ifdef ALT_BITSTREAM_READER_LE
result>>= (index&0x07);
result&= 1;
#else
result<<= (index&0x07);
result>>= 8 - 1;
#endif
index++;
s->index= index;
@ -687,7 +715,9 @@ void align_get_bits(GetBitContext *s);
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,
int use_static);
int flags);
#define INIT_VLC_USE_STATIC 1
#define INIT_VLC_LE 2
void free_vlc(VLC *vlc);
/**