mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-28 20:53:54 +02:00
76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
/*
|
|
* 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 */
|