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/*

 * Common bit i/o utils

 * Copyright (c) 2000, 2001 Fabrice Bellard

 * Copyright (c) 2002-2004 Michael Niedermayer 

 * Copyright (c) 2010 Loren Merritt

 *

 * alternative bitstream reader & writer by Michael Niedermayer 

 *

 * 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);

    }

    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<

            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;

}

void ff_free_vlc(VLC *vlc)

{

    av_freep(&vlc->table);

}