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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 FFMPEG_ACELP_MATH_H
#define FFMPEG_ACELP_MATH_H
#include <stdint.h>
/**
* \brief fixed-point implementation of cosine in [0; PI) domain
* \param arg fixed-point cosine argument, 0 <= arg < 0x4000
*
* \return value of (1<<15) * cos(arg * PI / (1<<14)), -0x8000 <= result <= 0x7fff
*/
int16_t ff_cos(uint16_t arg);
/**
* \brief 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);
/**
* \brief Calculates log2(x)
* \param value function argument, 0 < value <= 7fff ffff
*
* \return value of (1<<15) * log2(value)
*/
int ff_log2(uint32_t value);
/**
* \brief Calculates sum of array element multiplications
* \param speech input data array
* \param length number of elements
* \param offset offset for calculation of sum of s[i]*s[i+offset]
* \param shift right shift by this value will be done before multiplication
*
* \return sum of multiplications
*
* \note array must be at least length+offset long!
*/
static int sum_of_squares(const int16_t* speech, int length, int offset, int shift)
{
const int16_t* speech_end;
int sum = 0;
for(speech_end=speech+length; speech<speech_end; speech++)
sum += (speech[0] * speech[offset]) >> shift;
return sum;
}
#endif /* FFMPEG_ACELP_MATH_H */
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