| /* |
| * 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 "avcodec.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 ff_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; |
| 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 -1; |
| } |
| return index; |
| } |
| |
| static av_always_inline uint32_t bitswap_32(uint32_t x) { |
| return (uint32_t)av_reverse[x&0xFF]<<24 |
| | (uint32_t)av_reverse[(x>>8)&0xFF]<<16 |
| | (uint32_t)av_reverse[(x>>16)&0xFF]<<8 |
| | (uint32_t)av_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; |
| 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 -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++) { |
| 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 -1; |
| } |
| 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 -1; |
| /* 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; |
| |
| 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 { |
| vlc->table = NULL; |
| vlc->table_allocated = 0; |
| vlc->table_size = 0; |
| } |
| |
| av_dlog(NULL, "build table nb_codes=%d\n", nb_codes); |
| |
| buf = av_malloc((nb_codes+1)*sizeof(VLCcode)); |
| |
| assert(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;\ |
| GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);\ |
| 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); |
| |
| av_free(buf); |
| if (ret < 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 %d\n", vlc->table_size, vlc->table_allocated); |
| return 0; |
| } |
| |
| |
| void ff_free_vlc(VLC *vlc) |
| { |
| av_freep(&vlc->table); |
| } |
| |
