libavcodec/rl.h

   1 /*
   2  * Copyright (c) 2000-2002 Fabrice Bellard
   3  * Copyright (c) 2002-2004 Michael Niedermayer
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * rl header.
  25  */
  26
  27 #ifndef AVCODEC_RL_H
  28 #define AVCODEC_RL_H
  29
  30 #include <stdint.h>
  31
  32 #include "vlc.h"
  33
  34 /* run length table */
  35 #define MAX_RUN    64
  36 #define MAX_LEVEL  64
  37
  38 /** RLTable. */
  39 typedef struct RLTable {
  40     int n;                         ///< number of entries of table_vlc minus 1
  41     int last;                      ///< number of values for last = 0
  42     const uint16_t (*table_vlc)[2];
  43     const int8_t *table_run;
  44     const int8_t *table_level;
  45     uint8_t *index_run[2];         ///< encoding only
  46     int8_t *max_level[2];          ///< encoding & decoding
  47     int8_t *max_run[2];            ///< encoding & decoding
  48     RL_VLC_ELEM *rl_vlc[32];       ///< decoding only
  49 } RLTable;
  50
  51 /**
  52  * Initialize index_run, max_level and max_run from n, last, table_vlc,
  53  * table_run and table_level.
  54  * @param static_store static uint8_t array[2][2*MAX_RUN + MAX_LEVEL + 3]
  55  *                     to hold the level and run tables.
  56  * @note  This function does not touch rl_vlc at all, hence there is no need
  57  *        to synchronize calls to ff_rl_init() and ff_rl_init_vlc() using the
  58  *        same RLTable.
  59  */
  60 void ff_rl_init(RLTable *rl, uint8_t static_store[2][2*MAX_RUN + MAX_LEVEL + 3]);
  61
  62 /**
  63  * Initialize rl_vlc from n, last, table_vlc, table_run and table_level.
  64  * All rl_vlc pointers to be initialized must already point to a static
  65  * buffer of `static_size` RL_VLC_ELEM elements; if a pointer is NULL,
  66  * initializing further VLCs stops.
  67  * @note  This function does not touch what ff_rl_init() initializes at all,
  68  *        hence there is no need to synchronize calls to ff_rl_init() and
  69  *        ff_rl_init_vlc() using the same RLTable.
  70  */
  71 void ff_rl_init_vlc(RLTable *rl, unsigned static_size);
  72
  73 #define INIT_VLC_RL(rl, static_size)\
  74 {\
  75     static RL_VLC_ELEM rl_vlc_table[32][static_size];\
  76 \
  77     for (int q = 0; q < 32; q++) \
  78         rl.rl_vlc[q] = rl_vlc_table[q]; \
  79 \
  80     ff_rl_init_vlc(&rl, static_size); \
  81 }
  82
  83 #define INIT_FIRST_VLC_RL(rl, static_size)              \
  84 do {                                                    \
  85     static RL_VLC_ELEM rl_vlc_table[static_size];       \
  86                                                         \
  87     rl.rl_vlc[0] = rl_vlc_table;                        \
  88     ff_rl_init_vlc(&rl, static_size);                   \
  89 } while (0)
  90
  91 static inline int get_rl_index(const RLTable *rl, int last, int run, int level)
  92 {
  93     int index;
  94     index = rl->index_run[last][run];
  95     if (index >= rl->n)
  96         return rl->n;
  97     if (level > rl->max_level[last][run])
  98         return rl->n;
  99     return index + level - 1;
 100 }
 101
 102 #endif /* AVCODEC_RL_H */