libavcodec/celp_math.h

   1 /*
   2  * Various fixed-point math operations
   3  *
   4  * Copyright (c) 2008 Vladimir Voroshilov
   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 #ifndef AVCODEC_CELP_MATH_H
  24 #define AVCODEC_CELP_MATH_H
  25
  26 #include <stdint.h>
  27
  28 /**
  29  * fixed-point implementation of cosine in [0; PI) domain.
  30  * @param arg fixed-point cosine argument, 0 <= arg < 0x4000
  31  *
  32  * @return value of (1<<15) * cos(arg * PI / (1<<14)), -0x8000 <= result <= 0x7fff
  33  */
  34 int16_t ff_cos(uint16_t arg);
  35
  36 /**
  37  * fixed-point implementation of exp2(x) in [0; 1] domain.
  38  * @param power argument to exp2, 0 <= power <= 0x7fff
  39  *
  40  * @return value of (1<<20) * exp2(power / (1<<15))
  41  *         0x8000c <= result <= 0xfffea
  42  */
  43 int ff_exp2(uint16_t power);
  44
  45 /**
  46  * Calculates log2(x).
  47  * @param value function argument, 0 < value <= 7fff ffff
  48  *
  49  * @return value of (1<<15) * log2(value)
  50  */
  51 int ff_log2(uint32_t value);
  52
  53 /**
  54  * Shift value left or right depending on sign of offset parameter.
  55  * @param value value to shift
  56  * @param offset shift offset
  57  *
  58  * @return value << offset, if offset>=0; value >> -offset - otherwise
  59  */
  60 static inline int bidir_sal(int value, int offset)
  61 {
  62     if(offset < 0) return value >> -offset;
  63     else           return value <<  offset;
  64 }
  65
  66 /**
  67  * returns the dot product.
  68  * @param a input data array
  69  * @param b input data array
  70  * @param length number of elements
  71  *
  72  * @return dot product = sum of elementwise products
  73  */
  74 float ff_dot_productf(const float* a, const float* b, int length);
  75
  76 #endif /* AVCODEC_CELP_MATH_H */