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75 lines
2.2 KiB
75 lines
2.2 KiB
/* |
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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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#include <stdint.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 element multiplications |
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* \param speech input data array |
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* \param length number of elements |
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* \param offset offset for calculation of 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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