bitstream.c
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上传日期:2022-07-11
资源大小:334k
文件大小:11k
- /*
- * Common bit i/o utils
- * Copyright (c) 2000, 2001 Fabrice Bellard.
- * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
- *
- * 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.c
- * bitstream api.
- */
- #include "dsputil.h"
- //#include "internal.h"
- //#include "integer.h"
- //#include "avcodec.h"
- #include "bitstream.h"
- const uint8_t ff_log2_run[32]={
- 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
- };
- /**
- * Same as av_mallocz_static(), but does a realloc.
- *
- * @param[in] ptr The block of memory to reallocate.
- * @param[in] size The requested size.
- * @return Block of memory of requested size.
- * @deprecated. Code which uses ff_realloc_static is broken/misdesigned
- * and should correctly use static arrays
- */
- attribute_deprecated av_alloc_size(2)
- static void *ff_realloc_static(void *ptr, unsigned int size);
- static void *ff_realloc_static(void *ptr, unsigned int size)
- {
- return av_realloc(ptr, size);
- }
- void align_put_bits(PutBitContext *s)
- {
- #ifdef ALT_BITSTREAM_WRITER
- put_bits(s,( - s->index) & 7,0);
- #else
- put_bits(s,s->bit_left & 7,0);
- #endif
- }
- void ff_put_string(PutBitContext * pbc, const char *s, int put_zero)
- {
- while(*s){
- put_bits(pbc, 8, *s);
- s++;
- }
- if(put_zero)
- put_bits(pbc, 8, 0);
- }
- void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length)
- {
- const uint16_t *srcw= (const uint16_t*)src;
- int words= length>>4;
- int bits= length&15;
- int i;
- if(length==0) return;
- if(ENABLE_SMALL || words < 16 || put_bits_count(pb)&7){
- for(i=0; i<words; i++) put_bits(pb, 16, be2me_16(srcw[i]));
- }else{
- for(i=0; put_bits_count(pb)&31; i++)
- put_bits(pb, 8, src[i]);
- flush_put_bits(pb);
- memcpy(pbBufPtr(pb), src+i, 2*words-i);
- skip_put_bytes(pb, 2*words-i);
- }
- put_bits(pb, bits, be2me_16(srcw[words])>>(16-bits));
- }
- /* VLC decoding */
- //#define DEBUG_VLC
- #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;
- index = vlc->table_size;
- vlc->table_size += size;
- if (vlc->table_size > vlc->table_allocated) {
- if(use_static>1)
- abort(); //cant do anything, init_vlc() is used with too little memory
- vlc->table_allocated += (1 << vlc->bits);
- if(use_static)
- vlc->table = ff_realloc_static(vlc->table,
- sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
- else
- vlc->table = av_realloc(vlc->table,
- sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
- if (!vlc->table)
- return -1;
- }
- return index;
- }
- 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,
- const void *symbols, int symbols_wrap, int symbols_size,
- uint32_t code_prefix, int n_prefix, int flags)
- {
- int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2, symbol;
- uint32_t code;
- VLC_TYPE (*table)[2];
- table_size = 1 << table_nb_bits;
- table_index = alloc_table(vlc, table_size, flags & (INIT_VLC_USE_STATIC|INIT_VLC_USE_NEW_STATIC));
- #ifdef DEBUG_VLC
- av_log(NULL,AV_LOG_DEBUG,"new table index=%d size=%d code_prefix=%x n=%dn",
- table_index, table_size, code_prefix, n_prefix);
- #endif
- if (table_index < 0)
- return -1;
- 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 auxillary table sizes */
- for(i=0;i<nb_codes;i++) {
- GET_DATA(n, bits, i, bits_wrap, bits_size);
- GET_DATA(code, codes, i, codes_wrap, codes_size);
- /* we accept tables with holes */
- if (n <= 0)
- continue;
- if (!symbols)
- symbol = i;
- else
- GET_DATA(symbol, symbols, i, symbols_wrap, symbols_size);
- #if defined(DEBUG_VLC) && 0
- av_log(NULL,AV_LOG_DEBUG,"i=%d n=%d code=0x%xn", i, n, code);
- #endif
- /* if code matches the prefix, it is in the table */
- n -= n_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=%dn",
- j, i, n);
- #endif
- if (table[j][1] /*bits*/ != 0) {
- av_log(NULL, AV_LOG_ERROR, "incorrect codesn");
- return -1;
- }
- table[j][1] = n; //bits
- table[j][0] = symbol;
- j++;
- }
- } else {
- n -= table_nb_bits;
- j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
- #ifdef DEBUG_VLC
- av_log(NULL,AV_LOG_DEBUG,"%4x: n=%d (subtable)n",
- j, n);
- #endif
- /* compute table size */
- n1 = -table[j][1]; //bits
- if (n > n1)
- n1 = n;
- table[j][1] = -n1; //bits
- }
- }
- }
- /* second pass : fill auxillary tables recursively */
- for(i=0;i<table_size;i++) {
- n = table[i][1]; //bits
- if (n < 0) {
- n = -n;
- if (n > table_nb_bits) {
- n = table_nb_bits;
- table[i][1] = -n; //bits
- }
- index = build_table(vlc, n, nb_codes,
- bits, bits_wrap, bits_size,
- codes, codes_wrap, codes_size,
- symbols, symbols_wrap, symbols_size,
- (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 */
- table = &vlc->table[table_index];
- table[i][0] = index; //code
- }
- }
- 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 free_vlc() will be used.
- */
- int 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)
- {
- vlc->bits = nb_bits;
- if(flags & INIT_VLC_USE_NEW_STATIC){
- if(vlc->table_size && vlc->table_size == vlc->table_allocated){
- return 0;
- }else if(vlc->table_size){
- abort(); // fatal error, we are called on a partially initialized table
- }
- }else if(!(flags & INIT_VLC_USE_STATIC)) {
- vlc->table = NULL;
- vlc->table_allocated = 0;
- vlc->table_size = 0;
- } else {
- /* Static tables are initially always NULL, return
- if vlc->table != NULL to avoid double allocation */
- if(vlc->table)
- return 0;
- }
- #ifdef DEBUG_VLC
- av_log(NULL,AV_LOG_DEBUG,"build table nb_codes=%dn", nb_codes);
- #endif
- if (build_table(vlc, nb_bits, nb_codes,
- bits, bits_wrap, bits_size,
- codes, codes_wrap, codes_size,
- symbols, symbols_wrap, symbols_size,
- 0, 0, flags) < 0) {
- av_freep(&vlc->table);
- return -1;
- }
- if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size != vlc->table_allocated)
- av_log(NULL, AV_LOG_ERROR, "needed %d had %dn", vlc->table_size, vlc->table_allocated);
- return 0;
- }
- void free_vlc(VLC *vlc)
- {
- av_freep(&vlc->table);
- }