Fixed-point implementation of ff_cos, ff_log2, ff_exp2.
Also implemented routine for calculating sum(a[i] * a[i-offset]>>shift) Originally committed as revision 12974 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Vladimir Voroshilov
parent
bf52a72023
commit
1cf3ee2d1c
197
libavcodec/acelp_math.c
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197
libavcodec/acelp_math.c
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/*
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* Various fixed-point math operations
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*
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* Copyright (c) 2008 Vladimir Voroshilov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <inttypes.h>
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#include <limits.h>
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#include <assert.h>
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#include "avcodec.h"
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#include "acelp_math.h"
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#ifdef G729_BITEXACT
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/**
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* Cosine table: base_cos[i] = (1<<15) * cos(i*PI/64)
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*/
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static const int16_t base_cos[64] =
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{
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32767, 32729, 32610, 32413, 32138, 31786, 31357, 30853,
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30274, 29622, 28899, 28106, 27246, 26320, 25330, 24279,
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23170, 22006, 20788, 19520, 18205, 16846, 15447, 14010,
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12540, 11039, 9512, 7962, 6393, 4808, 3212, 1608,
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0, -1608, -3212, -4808, -6393, -7962, -9512, -11039,
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-12540, -14010, -15447, -16846, -18205, -19520, -20788, -22006,
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-23170, -24279, -25330, -26320, -27246, -28106, -28899, -29622,
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-30274, -30853, -31357, -31786, -32138, -32413, -32610, -32729
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};
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/**
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* Slope used to compute cos(x)
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*
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* cos(ind*64+offset) = base_cos[ind]+offset*slope_cos[ind]
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* values multiplied by 1<<19
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*/
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static const int16_t slope_cos[64] =
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{
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-632, -1893, -3150, -4399, -5638, -6863, -8072, -9261,
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-10428, -11570, -12684, -13767, -14817, -15832, -16808, -17744,
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-18637, -19486, -20287, -21039, -21741, -22390, -22986, -23526,
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-24009, -24435, -24801, -25108, -25354, -25540, -25664, -25726,
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-25726, -25664, -25540, -25354, -25108, -24801, -24435, -24009,
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-23526, -22986, -22390, -21741, -21039, -20287, -19486, -18637,
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-17744, -16808, -15832, -14817, -13767, -12684, -11570, -10428,
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-9261, -8072, -6863, -5638, -4399, -3150, -1893, -632
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};
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/**
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* Table used to compute exp2(x)
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*
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* tab_exp2[i] = (1<<14) * exp2(i/32) = 2^(i/32) i=0..32
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*/
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static const uint16_t tab_exp2[33] =
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{
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16384, 16743, 17109, 17484, 17867, 18258, 18658, 19066, 19484, 19911,
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20347, 20792, 21247, 21713, 22188, 22674, 23170, 23678, 24196, 24726,
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25268, 25821, 26386, 26964, 27554, 28158, 28774, 29405, 30048, 30706,
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31379, 32066, 32767
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};
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int16_t ff_cos(uint16_t arg)
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{
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uint8_t offset= arg;
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uint8_t ind = arg >> 8;
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assert(arg < 0x4000);
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return FFMAX(base_cos[ind] + ((slope_cos[ind] * offset) >> 12), -0x8000);
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}
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int ff_exp2(uint16_t power)
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{
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uint16_t frac_x0;
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uint16_t frac_dx;
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int result;
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assert(power <= 0x7fff);
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frac_x0 = power >> 10;
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frac_dx = (power & 0x03ff) << 5;
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result = tab_exp2[frac_x0] << 15;
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result += frac_dx * (tab_exp2[frac_x0+1] - tab_exp2[frac_x0]);
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return result >> 10;
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}
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#else // G729_BITEXACT
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/**
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* Cosine table: base_cos[i] = (1<<15) * cos(i*PI/64)
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*/
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static const int16_t tab_cos[65] =
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{
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32767, 32738, 32617, 32421, 32145, 31793, 31364, 30860,
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30280, 29629, 28905, 28113, 27252, 26326, 25336, 24285,
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23176, 22011, 20793, 19525, 18210, 16851, 15451, 14014,
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12543, 11043, 9515, 7965, 6395, 4810, 3214, 1609,
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1, -1607, -3211, -4808, -6393, -7962, -9513, -11040,
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-12541, -14012, -15449, -16848, -18207, -19523, -20791, -22009,
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-23174, -24283, -25334, -26324, -27250, -28111, -28904, -29627,
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-30279, -30858, -31363, -31792, -32144, -32419, -32616, -32736, -32768,
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};
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static const uint16_t exp2a[]=
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{
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0, 1435, 2901, 4400, 5931, 7496, 9096, 10730,
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12400, 14106, 15850, 17632, 19454, 21315, 23216, 25160,
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27146, 29175, 31249, 33368, 35534, 37747, 40009, 42320,
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44682, 47095, 49562, 52082, 54657, 57289, 59979, 62727,
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};
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static const uint16_t exp2b[]=
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{
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3, 712, 1424, 2134, 2845, 3557, 4270, 4982,
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5696, 6409, 7124, 7839, 8554, 9270, 9986, 10704,
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11421, 12138, 12857, 13576, 14295, 15014, 15734, 16455,
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17176, 17898, 18620, 19343, 20066, 20790, 21514, 22238,
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};
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int16_t ff_cos(uint16_t arg)
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{
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uint8_t offset= arg;
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uint8_t ind = arg >> 8;
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assert(arg <= 0x3fff);
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return tab_cos[ind] + (offset * (tab_cos[ind+1] - tab_cos[ind]) >> 8);
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}
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int ff_exp2(uint16_t power)
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{
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unsigned int result= exp2a[power>>10] + 0x10000;
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assert(arg <= 0x7fff);
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result= (result<<3) + ((result*exp2b[(power>>5)&31])>>17);
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return result + ((result*(power&31)*89)>>22);
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}
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#endif // else G729_BITEXACT
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/**
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* Table used to compute log2(x)
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*
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* tab_log2[i] = (1<<15) * log2(1 + i/32), i=0..32
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*/
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static const uint16_t tab_log2[33] =
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{
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#ifdef G729_BITEXACT
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0, 1455, 2866, 4236, 5568, 6863, 8124, 9352,
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10549, 11716, 12855, 13967, 15054, 16117, 17156, 18172,
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19167, 20142, 21097, 22033, 22951, 23852, 24735, 25603,
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26455, 27291, 28113, 28922, 29716, 30497, 31266, 32023, 32767,
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#else
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4, 1459, 2870, 4240, 5572, 6867, 8127, 9355,
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10552, 11719, 12858, 13971, 15057, 16120, 17158, 18175,
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19170, 20145, 21100, 22036, 22954, 23854, 24738, 25605,
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26457, 27294, 28116, 28924, 29719, 30500, 31269, 32025, 32769,
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#endif
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};
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int ff_log2(uint32_t value)
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{
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uint8_t power_int;
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uint8_t frac_x0;
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uint16_t frac_dx;
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// Stripping zeros from beginning
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power_int = av_log2(value);
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value <<= (31 - power_int);
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// b31 is always non-zero now
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frac_x0 = (value & 0x7c000000) >> 26; // b26-b31 and [32..63] -> [0..31]
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frac_dx = (value & 0x03fff800) >> 11;
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value = tab_log2[frac_x0];
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value += (frac_dx * (tab_log2[frac_x0+1] - tab_log2[frac_x0])) >> 15;
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return (power_int << 15) + value;
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}
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73
libavcodec/acelp_math.h
Normal file
73
libavcodec/acelp_math.h
Normal file
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@ -0,0 +1,73 @@
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/*
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* Various fixed-point math operations
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*
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* Copyright (c) 2008 Vladimir Voroshilov
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef FFMPEG_ACELP_MATH_H
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#define FFMPEG_ACELP_MATH_H
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/**
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* \brief fixed-point implementation of cosine in [0; PI) domain
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* \param arg fixed-point cosine argument, 0 <= arg < 0x4000
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*
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* \return value of (1<<15) * cos(arg * PI / (1<<14)), -0x8000 <= result <= 0x7fff
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*/
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int16_t ff_cos(uint16_t arg);
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/**
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* \brief fixed-point implementation of exp2(x) in [0; 1] domain
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* \param power argument to exp2, 0 <= power <= 0x7fff
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*
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* \return value of (1<<20) * exp2(power / (1<<15))
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* 0x8000c <= result <= 0xfffea
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*/
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int ff_exp2(uint16_t power);
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/**
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* \brief Calculates log2(x)
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* \param value function argument, 0 < value <= 7fff ffff
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*
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* \return value of (1<<15) * log2(value)
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*/
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int ff_log2(uint32_t value);
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/**
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* \brief Calculates sum of array elements multiplications
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* \param speech array with input data
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* \param length number elements to proceed
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* \param offset offset for calculation sum of s[i]*s[i+offset]
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* \param shift right shift by this value will be done before multiplication
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*
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* \return sum of multiplications
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*
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* \note array must be at least length+offset long!
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*/
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static int sum_of_squares(const int16_t* speech, int length, int offset, int shift)
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{
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const int16_t* speech_end;
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int sum = 0;
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for(speech_end=speech+length; speech<speech_end; speech++)
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sum += (speech[0] * speech[offset]) >> shift;
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return sum;
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}
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#endif // FFMPEG_ACELP_MATH_H
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