0,0 → 1,356 |
/* |
* Common bit i/o utils |
* Copyright (c) 2000, 2001 Fabrice Bellard |
* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
* Copyright (c) 2010 Loren Merritt |
* |
* alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at> |
* |
* This file is part of FFmpeg. |
* |
* FFmpeg is free software; you can redistribute it and/or |
* modify it under the terms of the GNU Lesser General Public |
* License as published by the Free Software Foundation; either |
* version 2.1 of the License, or (at your option) any later version. |
* |
* FFmpeg is distributed in the hope that it will be useful, |
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
* Lesser General Public License for more details. |
* |
* You should have received a copy of the GNU Lesser General Public |
* License along with FFmpeg; if not, write to the Free Software |
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
*/ |
|
/** |
* @file |
* bitstream api. |
*/ |
|
#include "libavutil/atomic.h" |
#include "libavutil/avassert.h" |
#include "avcodec.h" |
#include "mathops.h" |
#include "get_bits.h" |
#include "put_bits.h" |
|
const uint8_t ff_log2_run[41]={ |
0, 0, 0, 0, 1, 1, 1, 1, |
2, 2, 2, 2, 3, 3, 3, 3, |
4, 4, 5, 5, 6, 6, 7, 7, |
8, 9,10,11,12,13,14,15, |
16,17,18,19,20,21,22,23, |
24, |
}; |
|
void avpriv_align_put_bits(PutBitContext *s) |
{ |
put_bits(s, s->bit_left & 7, 0); |
} |
|
void avpriv_put_string(PutBitContext *pb, const char *string, |
int terminate_string) |
{ |
while (*string) { |
put_bits(pb, 8, *string); |
string++; |
} |
if (terminate_string) |
put_bits(pb, 8, 0); |
} |
|
void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length) |
{ |
int words = length >> 4; |
int bits = length & 15; |
int i; |
|
if (length == 0) |
return; |
|
if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) { |
for (i = 0; i < words; i++) |
put_bits(pb, 16, AV_RB16(src + 2 * i)); |
} else { |
for (i = 0; put_bits_count(pb) & 31; i++) |
put_bits(pb, 8, src[i]); |
flush_put_bits(pb); |
memcpy(put_bits_ptr(pb), src + i, 2 * words - i); |
skip_put_bytes(pb, 2 * words - i); |
} |
|
put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits)); |
} |
|
/* VLC decoding */ |
|
#define GET_DATA(v, table, i, wrap, size) \ |
{ \ |
const uint8_t *ptr = (const uint8_t *)table + i * wrap; \ |
switch(size) { \ |
case 1: \ |
v = *(const uint8_t *)ptr; \ |
break; \ |
case 2: \ |
v = *(const uint16_t *)ptr; \ |
break; \ |
default: \ |
v = *(const uint32_t *)ptr; \ |
break; \ |
} \ |
} |
|
|
static int alloc_table(VLC *vlc, int size, int use_static) |
{ |
int index = vlc->table_size; |
|
vlc->table_size += size; |
if (vlc->table_size > vlc->table_allocated) { |
if (use_static) |
abort(); // cannot do anything, init_vlc() is used with too little memory |
vlc->table_allocated += (1 << vlc->bits); |
vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2); |
if (!vlc->table) |
return AVERROR(ENOMEM); |
} |
return index; |
} |
|
static av_always_inline uint32_t bitswap_32(uint32_t x) |
{ |
return (uint32_t)ff_reverse[ x & 0xFF] << 24 | |
(uint32_t)ff_reverse[(x >> 8) & 0xFF] << 16 | |
(uint32_t)ff_reverse[(x >> 16) & 0xFF] << 8 | |
(uint32_t)ff_reverse[ x >> 24]; |
} |
|
typedef struct { |
uint8_t bits; |
uint16_t symbol; |
/** codeword, with the first bit-to-be-read in the msb |
* (even if intended for a little-endian bitstream reader) */ |
uint32_t code; |
} VLCcode; |
|
static int compare_vlcspec(const void *a, const void *b) |
{ |
const VLCcode *sa = a, *sb = b; |
return (sa->code >> 1) - (sb->code >> 1); |
} |
/** |
* Build VLC decoding tables suitable for use with get_vlc(). |
* |
* @param vlc the context to be initted |
* |
* @param table_nb_bits max length of vlc codes to store directly in this table |
* (Longer codes are delegated to subtables.) |
* |
* @param nb_codes number of elements in codes[] |
* |
* @param codes descriptions of the vlc codes |
* These must be ordered such that codes going into the same subtable are contiguous. |
* Sorting by VLCcode.code is sufficient, though not necessary. |
*/ |
static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, |
VLCcode *codes, int flags) |
{ |
int table_size, table_index, index, code_prefix, symbol, subtable_bits; |
int i, j, k, n, nb, inc; |
uint32_t code; |
VLC_TYPE (*table)[2]; |
|
table_size = 1 << table_nb_bits; |
if (table_nb_bits > 30) |
return -1; |
table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC); |
av_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size); |
if (table_index < 0) |
return table_index; |
table = &vlc->table[table_index]; |
|
for (i = 0; i < table_size; i++) { |
table[i][1] = 0; //bits |
table[i][0] = -1; //codes |
} |
|
/* first pass: map codes and compute auxiliary table sizes */ |
for (i = 0; i < nb_codes; i++) { |
n = codes[i].bits; |
code = codes[i].code; |
symbol = codes[i].symbol; |
av_dlog(NULL, "i=%d n=%d code=0x%x\n", i, n, code); |
if (n <= table_nb_bits) { |
/* no need to add another table */ |
j = code >> (32 - table_nb_bits); |
nb = 1 << (table_nb_bits - n); |
inc = 1; |
if (flags & INIT_VLC_LE) { |
j = bitswap_32(code); |
inc = 1 << n; |
} |
for (k = 0; k < nb; k++) { |
av_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n); |
if (table[j][1] /*bits*/ != 0) { |
av_log(NULL, AV_LOG_ERROR, "incorrect codes\n"); |
return AVERROR_INVALIDDATA; |
} |
table[j][1] = n; //bits |
table[j][0] = symbol; |
j += inc; |
} |
} else { |
/* fill auxiliary table recursively */ |
n -= table_nb_bits; |
code_prefix = code >> (32 - table_nb_bits); |
subtable_bits = n; |
codes[i].bits = n; |
codes[i].code = code << table_nb_bits; |
for (k = i+1; k < nb_codes; k++) { |
n = codes[k].bits - table_nb_bits; |
if (n <= 0) |
break; |
code = codes[k].code; |
if (code >> (32 - table_nb_bits) != code_prefix) |
break; |
codes[k].bits = n; |
codes[k].code = code << table_nb_bits; |
subtable_bits = FFMAX(subtable_bits, n); |
} |
subtable_bits = FFMIN(subtable_bits, table_nb_bits); |
j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix; |
table[j][1] = -subtable_bits; |
av_dlog(NULL, "%4x: n=%d (subtable)\n", |
j, codes[i].bits + table_nb_bits); |
index = build_table(vlc, subtable_bits, k-i, codes+i, flags); |
if (index < 0) |
return index; |
/* note: realloc has been done, so reload tables */ |
table = &vlc->table[table_index]; |
table[j][0] = index; //code |
i = k-1; |
} |
} |
return table_index; |
} |
|
|
/* Build VLC decoding tables suitable for use with get_vlc(). |
|
'nb_bits' set thee decoding table size (2^nb_bits) entries. The |
bigger it is, the faster is the decoding. But it should not be too |
big to save memory and L1 cache. '9' is a good compromise. |
|
'nb_codes' : number of vlcs codes |
|
'bits' : table which gives the size (in bits) of each vlc code. |
|
'codes' : table which gives the bit pattern of of each vlc code. |
|
'symbols' : table which gives the values to be returned from get_vlc(). |
|
'xxx_wrap' : give the number of bytes between each entry of the |
'bits' or 'codes' tables. |
|
'xxx_size' : gives the number of bytes of each entry of the 'bits' |
or 'codes' tables. |
|
'wrap' and 'size' allows to use any memory configuration and types |
(byte/word/long) to store the 'bits', 'codes', and 'symbols' tables. |
|
'use_static' should be set to 1 for tables, which should be freed |
with av_free_static(), 0 if ff_free_vlc() will be used. |
*/ |
int ff_init_vlc_sparse(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, |
const void *symbols, int symbols_wrap, int symbols_size, |
int flags) |
{ |
VLCcode *buf; |
int i, j, ret; |
VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34 |
void *state; |
|
vlc->bits = nb_bits; |
if (flags & INIT_VLC_USE_NEW_STATIC) { |
while (state = avpriv_atomic_ptr_cas(&vlc->init_state, NULL, vlc)) { |
if (state == vlc + 1) { |
av_assert0(vlc->table_size && vlc->table_size == vlc->table_allocated); |
return 0; |
} |
} |
av_assert0(!vlc->table_size); |
av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf)); |
buf = localbuf; |
} else { |
vlc->table = NULL; |
vlc->table_allocated = 0; |
vlc->table_size = 0; |
|
buf = av_malloc((nb_codes + 1) * sizeof(VLCcode)); |
if (!buf) |
return AVERROR(ENOMEM); |
} |
|
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av_assert0(symbols_size <= 2 || !symbols); |
j = 0; |
#define COPY(condition)\ |
for (i = 0; i < nb_codes; i++) { \ |
GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size); \ |
if (!(condition)) \ |
continue; \ |
if (buf[j].bits > 3*nb_bits || buf[j].bits>32) { \ |
av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\ |
if (!(flags & INIT_VLC_USE_NEW_STATIC)) \ |
av_free(buf); \ |
return -1; \ |
} \ |
GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \ |
if (buf[j].code >= (1LL<<buf[j].bits)) { \ |
av_log(NULL, AV_LOG_ERROR, "Invalid code in init_vlc\n"); \ |
if (!(flags & INIT_VLC_USE_NEW_STATIC)) \ |
av_free(buf); \ |
return -1; \ |
} \ |
if (flags & INIT_VLC_LE) \ |
buf[j].code = bitswap_32(buf[j].code); \ |
else \ |
buf[j].code <<= 32 - buf[j].bits; \ |
if (symbols) \ |
GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \ |
else \ |
buf[j].symbol = i; \ |
j++; \ |
} |
COPY(buf[j].bits > nb_bits); |
// qsort is the slowest part of init_vlc, and could probably be improved or avoided |
qsort(buf, j, sizeof(VLCcode), compare_vlcspec); |
COPY(buf[j].bits && buf[j].bits <= nb_bits); |
nb_codes = j; |
|
ret = build_table(vlc, nb_bits, nb_codes, buf, flags); |
|
if (flags & INIT_VLC_USE_NEW_STATIC) { |
if(vlc->table_size != vlc->table_allocated) |
av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated); |
state = avpriv_atomic_ptr_cas(&vlc->init_state, vlc, vlc+1); |
av_assert0(state == vlc); |
av_assert0(ret >= 0); |
} else { |
av_free(buf); |
if (ret < 0) { |
av_freep(&vlc->table); |
return ret; |
} |
} |
return 0; |
} |
|
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void ff_free_vlc(VLC *vlc) |
{ |
av_freep(&vlc->table); |
} |