/*
  * 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;

     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 -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);

 }