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  1. /*
  2.  * ELS (Entropy Logarithmic-Scale) decoder
  3.  *
  4.  * Copyright (c) 2013 Maxim Poliakovski
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * Entropy Logarithmic-Scale binary arithmetic coder
  26.  */
  27.  
  28. #ifndef AVCODEC_ELSDEC_H
  29. #define AVCODEC_ELSDEC_H
  30.  
  31. #include <stdint.h>
  32. #include <sys/types.h>
  33.  
  34. #define ELS_EXPGOLOMB_LEN   10
  35.  
  36. typedef struct ElsDecCtx {
  37.     const uint8_t *in_buf;
  38.     unsigned x;
  39.     size_t data_size;
  40.     int j, t, diff, err;
  41. } ElsDecCtx;
  42.  
  43. typedef struct ElsRungNode {
  44.     uint8_t  rung;
  45.     uint16_t next_index;
  46. } ElsRungNode;
  47.  
  48. typedef struct ElsUnsignedRung {
  49.     uint8_t      prefix_rung[ELS_EXPGOLOMB_LEN + 1];
  50.     ElsRungNode  *rem_rung_list;
  51.     size_t       rung_list_size;
  52.     uint16_t     avail_index;
  53. } ElsUnsignedRung;
  54.  
  55. void ff_els_decoder_init(ElsDecCtx *ctx, const uint8_t *in, size_t data_size);
  56. void ff_els_decoder_uninit(ElsUnsignedRung *rung);
  57. int  ff_els_decode_bit(ElsDecCtx *ctx, unsigned char *rung);
  58. unsigned ff_els_decode_unsigned(ElsDecCtx *ctx, ElsUnsignedRung *ur);
  59.  
  60. #endif /* AVCODEC_ELSDEC_H */
  61.