f0c07be649
This name is more descriptive as the function returns a fixed-point value with 15 fraction bits. Signed-off-by: Mans Rullgard <mans@mansr.com>
59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
/*
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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 Libav.
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*
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* Libav 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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* Libav 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 Libav; 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 AVCODEC_CELP_MATH_H
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#define AVCODEC_CELP_MATH_H
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#include <stdint.h>
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/**
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* 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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* Calculate 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_q15(uint32_t value);
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/**
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* Shift value left or right depending on sign of offset parameter.
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* @param value value to shift
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* @param offset shift offset
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*
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* @return value << offset, if offset>=0; value >> -offset - otherwise
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*/
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static inline int bidir_sal(int value, int offset)
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{
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if(offset < 0) return value >> -offset;
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else return value << offset;
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}
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#endif /* AVCODEC_CELP_MATH_H */
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