libavcodec/rl.c

   1 /*
   2  * This file is part of Libav.
   3  *
   4  * Libav is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * Libav is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with Libav; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17  */
  18
  19 #include <stdint.h>
  20 #include <string.h>
  21
  22 #include "libavutil/attributes.h"
  23 #include "libavutil/mem.h"
  24
  25 #include "rl.h"
  26
  27 void ff_rl_free(RLTable *rl)
  28 {
  29     int i;
  30
  31     for (i = 0; i < 2; i++) {
  32         av_freep(&rl->max_run[i]);
  33         av_freep(&rl->max_level[i]);
  34         av_freep(&rl->index_run[i]);
  35     }
  36 }
  37
  38 av_cold int ff_rl_init(RLTable *rl,
  39                        uint8_t static_store[2][2 * MAX_RUN + MAX_LEVEL + 3])
  40 {
  41     int8_t  max_level[MAX_RUN + 1], max_run[MAX_LEVEL + 1];
  42     uint8_t index_run[MAX_RUN + 1];
  43     int last, run, level, start, end, i;
  44
  45     /* If table is static, we can quit if rl->max_level[0] is not NULL */
  46     if (static_store && rl->max_level[0])
  47         return 0;
  48
  49     /* compute max_level[], max_run[] and index_run[] */
  50     for (last = 0; last < 2; last++) {
  51         if (last == 0) {
  52             start = 0;
  53             end = rl->last;
  54         } else {
  55             start = rl->last;
  56             end = rl->n;
  57         }
  58
  59         memset(max_level, 0, MAX_RUN + 1);
  60         memset(max_run, 0, MAX_LEVEL + 1);
  61         memset(index_run, rl->n, MAX_RUN + 1);
  62         for (i = start; i < end; i++) {
  63             run   = rl->table_run[i];
  64             level = rl->table_level[i];
  65             if (index_run[run] == rl->n)
  66                 index_run[run] = i;
  67             if (level > max_level[run])
  68                 max_level[run] = level;
  69             if (run > max_run[level])
  70                 max_run[level] = run;
  71         }
  72         if (static_store)
  73             rl->max_level[last] = static_store[last];
  74         else {
  75             rl->max_level[last] = av_malloc(MAX_RUN + 1);
  76             if (!rl->max_level[last])
  77                 goto fail;
  78         }
  79         memcpy(rl->max_level[last], max_level, MAX_RUN + 1);
  80         if (static_store)
  81             rl->max_run[last]   = static_store[last] + MAX_RUN + 1;
  82         else {
  83             rl->max_run[last]   = av_malloc(MAX_LEVEL + 1);
  84             if (!rl->max_run[last])
  85                 goto fail;
  86         }
  87         memcpy(rl->max_run[last], max_run, MAX_LEVEL + 1);
  88         if (static_store)
  89             rl->index_run[last] = static_store[last] + MAX_RUN + MAX_LEVEL + 2;
  90         else {
  91             rl->index_run[last] = av_malloc(MAX_RUN + 1);
  92             if (!rl->index_run[last])
  93                 goto fail;
  94         }
  95         memcpy(rl->index_run[last], index_run, MAX_RUN + 1);
  96     }
  97     return 0;
  98
  99 fail:
 100     ff_rl_free(rl);
 101     return AVERROR(ENOMEM);
 102 }
 103
 104 av_cold void ff_rl_init_vlc(RLTable *rl)
 105 {
 106     int i, q;
 107
 108     for (q = 0; q < 32; q++) {
 109         int qmul = q * 2;
 110         int qadd = (q - 1) | 1;
 111
 112         if (q == 0) {
 113             qmul = 1;
 114             qadd = 0;
 115         }
 116         for (i = 0; i < rl->vlc.table_size; i++) {
 117             int code = rl->vlc.table[i][0];
 118             int len  = rl->vlc.table[i][1];
 119             int level, run;
 120
 121             if (len == 0) { // illegal code
 122                 run   = 66;
 123                 level = MAX_LEVEL;
 124             } else if (len < 0) { // more bits needed
 125                 run   = 0;
 126                 level = code;
 127             } else {
 128                 if (code == rl->n) { // esc
 129                     run   = 66;
 130                     level =  0;
 131                 } else {
 132                     run   = rl->table_run[code] + 1;
 133                     level = rl->table_level[code] * qmul + qadd;
 134                     if (code >= rl->last) run += 192;
 135                 }
 136             }
 137             rl->rl_vlc[q][i].len   = len;
 138             rl->rl_vlc[q][i].level = level;
 139             rl->rl_vlc[q][i].run   = run;
 140         }
 141     }
 142 }