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ffmpeg-4.2.2/libavcodec/celp_math.h 2.66 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Various fixed-point math operations
   *
   * Copyright (c) 2008 Vladimir Voroshilov
   *
   * 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_CELP_MATH_H
  #define AVCODEC_CELP_MATH_H
  
  #include <stdint.h>
  
  typedef struct CELPMContext {
      /**
       * Return the dot product.
       * @param a input data array
       * @param b input data array
       * @param length number of elements
       *
       * @return dot product = sum of elementwise products
       */
      float (*dot_productf)(const float* a, const float* b, int length);
  
  }CELPMContext;
  
  /**
   * Initialize CELPMContext.
   */
  void ff_celp_math_init(CELPMContext *c);
  void ff_celp_math_init_mips(CELPMContext *c);
  
  /**
   * fixed-point implementation of exp2(x) in [0; 1] domain.
   * @param power argument to exp2, 0 <= power <= 0x7fff
   *
   * @return value of (1<<20) * exp2(power / (1<<15))
   *         0x8000c <= result <= 0xfffea
   */
  int ff_exp2(uint16_t power);
  
  /**
   * Calculate log2(x).
   * @param value function argument, 0 < value <= 7fff ffff
   *
   * @return value of (1<<15) * log2(value)
   */
  int ff_log2_q15(uint32_t value);
  
  /**
   * Calculate the dot product of 2 int16_t vectors.
   * @param a input data array
   * @param b input data array
   * @param length number of elements
   *
   * @return dot product = sum of elementwise products
   */
  int64_t ff_dot_product(const int16_t *a, const int16_t *b, int length);
  
  /**
   * Shift value left or right depending on sign of offset parameter.
   * @param value value to shift
   * @param offset shift offset
   *
   * @return value << offset, if offset>=0; value >> -offset - otherwise
   */
  static inline int bidir_sal(int value, int offset)
  {
      if(offset < 0) return value >> -offset;
      else           return value <<  offset;
  }
  
  /**
   * Return the dot product.
   * @param a input data array
   * @param b input data array
   * @param length number of elements
   *
   * @return dot product = sum of elementwise products
   */
  float ff_dot_productf(const float* a, const float* b, int length);
  
  #endif /* AVCODEC_CELP_MATH_H */