/*
  * 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 "libavutil/qsort.h"

 #include "avcodec.h"

 #include "internal.h"

 #include "mathops.h"

 #include "put_bits.h"

 #include "vlc.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;

     av_assert0(length <= put_bits_left(pb));
 

     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) {

             vlc->table_allocated = 0;
             vlc->table_size = 0;

             return AVERROR(ENOMEM);

         }

         memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);

     }
     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 initialized

  *
  * @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;

     volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent an internal compiler error in gcc 4.2

 
     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);

     ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);

     if (table_index < 0)

         return table_index;

     table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];

     /* 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++) {

                 int bits = table[j][1];

                 ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);

                 if (bits != 0 && bits != n) {

                     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 = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];

             table[j][0] = index; //code
             i = k-1;
         }

     }

 
     for (i = 0; i < table_size; i++) {
         if (table[i][1] == 0) //bits
             table[i][0] = -1; //codes
     }
 

     return table_index;
 }
 
 

 /* Build VLC decoding tables suitable for use with get_vlc().
 

    'nb_bits' sets the 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' make it possible 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_arg, 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

     VLC localvlc, *vlc;

     vlc = vlc_arg;

     vlc->bits = nb_bits;

     if (flags & INIT_VLC_USE_NEW_STATIC) {

         av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf));
         buf = localbuf;

         localvlc = *vlc_arg;
         vlc = &localvlc;
         vlc->table_size = 0;

     } else {
         vlc->table           = NULL;

         vlc->table_allocated = 0;

         vlc->table_size      = 0;

         buf = av_malloc_array((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<<buf[j].bits)) {                            \

             av_log(NULL, AV_LOG_ERROR, "Invalid code %x for %d in init_vlc\n", buf[j].code, i);\

             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

     AV_QSORT(buf, j, struct 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);

         av_assert0(ret >= 0);

         *vlc_arg = *vlc;

     } 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);

 }