/* * 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 Libav. * * Libav 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. * * Libav 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 Libav; 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 "internal.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) {        int err;        if (use_static)            return AVERROR_BUG;        vlc->table_allocated += (1 << vlc->bits);        if ((err = av_reallocp(&vlc->table,                               sizeof(VLC_TYPE) * 2 *                               vlc->table_allocated)) < 0) {            vlc->table_allocated = 0;            vlc->table_size = 0;            return err;        }    }    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 VLCcode {    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);    ff_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;        ff_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++) {                ff_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;            ff_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;     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) {            return AVERROR_BUG;        }    } else {        vlc->table           = NULL;        vlc->table_allocated = 0;        vlc->table_size      = 0;    }     ff_dlog(NULL, "build table nb_codes=%d\n", nb_codes);     buf = av_malloc((nb_codes + 1) * sizeof(VLCcode));    if (!buf)        return AVERROR(ENOMEM);     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 ret;    }    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);}