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ffmpeg-4.2.2/libavcodec/unary.h 1.84 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * copyright (c) 2004 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
   */
  
  #ifndef AVCODEC_UNARY_H
  #define AVCODEC_UNARY_H
  
  #include "get_bits.h"
  
  /**
   * Get unary code of limited length
   * @param gb GetBitContext
   * @param[in] stop The bitstop value (unary code of 1's or 0's)
   * @param[in] len Maximum length
   * @return unary 0 based code index. This is also the length in bits of the
   * code excluding the stop bit.
   * (in case len=1)
   * 1            0
   * 0            1
   * (in case len=2)
   * 1            0
   * 01           1
   * 00           2
   * (in case len=3)
   * 1            0
   * 01           1
   * 001          2
   * 000          3
   */
  static inline int get_unary(GetBitContext *gb, int stop, int len)
  {
      int i;
  
      for(i = 0; i < len && get_bits1(gb) != stop; i++);
      return i;
  }
  
  /**
   * Get unary code terminated by a 0 with a maximum length of 33
   * @param gb GetBitContext
   * @return Unary length/index
   */
  static inline int get_unary_0_33(GetBitContext *gb)
  {
      return get_unary(gb, 0, 33);
  }
  
  static inline int get_unary_0_9(GetBitContext *gb)
  {
      return get_unary(gb, 0, 9);
  }
  
  #endif /* AVCODEC_UNARY_H */