libavcodec/celp_math.c

   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 #include <stdint.h>
  24
  25 #include "config.h"
  26 #include "libavutil/avassert.h"
  27 #include "libavutil/intmath.h"
  28 #include "mathops.h"
  29 #include "celp_math.h"
  30
  31 #ifdef G729_BITEXACT
  32 static const uint16_t exp2a[]=
  33 {
  34      0,  1435,  2901,  4400,  5931,  7496,  9096, 10730,
  35  12400, 14106, 15850, 17632, 19454, 21315, 23216, 25160,
  36  27146, 29175, 31249, 33368, 35534, 37747, 40009, 42320,
  37  44682, 47095, 49562, 52082, 54657, 57289, 59979, 62727,
  38 };
  39
  40 static const uint16_t exp2b[]=
  41 {
  42      3,   712,  1424,  2134,  2845,  3557,  4270,  4982,
  43   5696,  6409,  7124,  7839,  8554,  9270,  9986, 10704,
  44  11421, 12138, 12857, 13576, 14295, 15014, 15734, 16455,
  45  17176, 17898, 18620, 19343, 20066, 20790, 21514, 22238,
  46 };
  47
  48 int ff_exp2(uint16_t power)
  49 {
  50     unsigned int result= exp2a[power>>10] + 0x10000;
  51
  52     av_assert2(power <= 0x7fff);
  53
  54     result= (result<<3) + ((result*exp2b[(power>>5)&31])>>17);
  55     return result + ((result*(power&31)*89)>>22);
  56 }
  57 #endif
  58
  59 /**
  60  * Table used to compute log2(x)
  61  *
  62  * tab_log2[i] = (1<<15) * log2(1 + i/32), i=0..32
  63  */
  64 static const uint16_t tab_log2[33] =
  65 {
  66 #ifdef G729_BITEXACT
  67       0,   1455,   2866,   4236,   5568,   6863,   8124,   9352,
  68   10549,  11716,  12855,  13967,  15054,  16117,  17156,  18172,
  69   19167,  20142,  21097,  22033,  22951,  23852,  24735,  25603,
  70   26455,  27291,  28113,  28922,  29716,  30497,  31266,  32023,  32767,
  71 #else
  72       4,   1459,   2870,   4240,   5572,   6867,   8127,   9355,
  73   10552,  11719,  12858,  13971,  15057,  16120,  17158,  18175,
  74   19170,  20145,  21100,  22036,  22954,  23854,  24738,  25605,
  75   26457,  27294,  28116,  28924,  29719,  30500,  31269,  32025,  32769,
  76 #endif
  77 };
  78
  79 int ff_log2_q15(uint32_t value)
  80 {
  81     uint8_t  power_int;
  82     uint8_t  frac_x0;
  83     uint16_t frac_dx;
  84
  85     // Stripping zeros from beginning
  86     power_int = av_log2(value);
  87     value <<= (31 - power_int);
  88
  89     // b31 is always non-zero now
  90     frac_x0 = (value & 0x7c000000) >> 26; // b26-b31 and [32..63] -> [0..31]
  91     frac_dx = (value & 0x03fff800) >> 11;
  92
  93     value = tab_log2[frac_x0];
  94     value += (frac_dx * (tab_log2[frac_x0+1] - tab_log2[frac_x0])) >> 15;
  95
  96     return (power_int << 15) + value;
  97 }
  98
  99 int64_t ff_dot_product(const int16_t *a, const int16_t *b, int length)
 100 {
 101     int i;
 102     int64_t sum = 0;
 103
 104     for (i = 0; i < length; i++)
 105         sum += MUL16(a[i], b[i]);
 106
 107     return sum;
 108 }
 109
 110 float ff_dot_productf(const float* a, const float* b, int length)
 111 {
 112     float sum = 0;
 113     int i;
 114
 115     for(i=0; i<length; i++)
 116         sum += a[i] * b[i];
 117
 118     return sum;
 119 }
 120
 121 void ff_celp_math_init(CELPMContext *c)
 122 {
 123     c->dot_productf   = ff_dot_productf;
 124
 125 #if HAVE_MIPSFPU
 126     ff_celp_math_init_mips(c);
 127 #endif
 128 }