mirror of
https://git.ffmpeg.org/ffmpeg.git
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116 lines
3.6 KiB
C
116 lines
3.6 KiB
C
/*
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* Copyright (c) 2016 Umair Khan <omerjerk@gmail.com>
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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 AVUTIL_SOFTFLOAT_IEEE754_H
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#define AVUTIL_SOFTFLOAT_IEEE754_H
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#include <stdint.h>
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#define EXP_BIAS 127
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#define MANT_BITS 23
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typedef struct SoftFloat_IEEE754 {
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int32_t sign;
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uint64_t mant;
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int32_t exp;
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} SoftFloat_IEEE754;
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static const SoftFloat_IEEE754 FLOAT_0 = {0, 0, -126};
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static const SoftFloat_IEEE754 FLOAT_1 = {0, 0, 0};
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/** Normalize the softfloat as defined by IEEE 754 single-recision floating
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* point specification
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*/
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static inline SoftFloat_IEEE754 av_normalize_sf_ieee754(SoftFloat_IEEE754 sf) {
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while( sf.mant >= 0x1000000UL ) {
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sf.exp++;
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sf.mant >>= 1;
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}
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sf.mant &= 0x007fffffUL;
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return sf;
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}
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/** Convert integer to softfloat.
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* @return softfloat with value n * 2^e
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*/
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static inline SoftFloat_IEEE754 av_int2sf_ieee754(int64_t n, int e) {
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int sign = 0;
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if (n < 0) {
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sign = 1;
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n *= -1;
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}
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return av_normalize_sf_ieee754((SoftFloat_IEEE754) {sign, n << MANT_BITS, 0 + e});
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}
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/** Make a softfloat out of the bitstream. Assumes the bits are in the form as defined
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* by the IEEE 754 spec.
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*/
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static inline SoftFloat_IEEE754 av_bits2sf_ieee754(uint32_t n) {
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return ((SoftFloat_IEEE754) { (n & 0x80000000UL) >> 31, (n & 0x7FFFFFUL), (int8_t)((n & 0x7F800000UL) >> 23)});
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}
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/** Convert the softfloat to integer
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*/
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static inline int av_sf2int_ieee754(SoftFloat_IEEE754 a) {
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if(a.exp >= 0) return a.mant << a.exp ;
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else return a.mant >>(-a.exp);
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}
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/** Divide a by b. b should not be zero.
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* @return normalized result
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*/
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static inline SoftFloat_IEEE754 av_div_sf_ieee754(SoftFloat_IEEE754 a, SoftFloat_IEEE754 b) {
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int32_t mant, exp, sign;
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a = av_normalize_sf_ieee754(a);
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b = av_normalize_sf_ieee754(b);
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sign = a.sign ^ b.sign;
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mant = ((((uint64_t) (a.mant | 0x00800000UL)) << MANT_BITS) / (b.mant| 0x00800000UL));
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exp = a.exp - b.exp;
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return av_normalize_sf_ieee754((SoftFloat_IEEE754) {sign, mant, exp});
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}
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/** Multiply a with b
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* #return normalized result
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*/
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static inline SoftFloat_IEEE754 av_mul_sf_ieee754(SoftFloat_IEEE754 a, SoftFloat_IEEE754 b) {
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int32_t sign, mant, exp;
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a = av_normalize_sf_ieee754(a);
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b = av_normalize_sf_ieee754(b);
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sign = a.sign ^ b.sign;
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mant = (((uint64_t)(a.mant|0x00800000UL) * (uint64_t)(b.mant|0x00800000UL))>>MANT_BITS);
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exp = a.exp + b.exp;
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return av_normalize_sf_ieee754((SoftFloat_IEEE754) {sign, mant, exp});
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}
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/** Compare a with b strictly
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* @returns 1 if the a and b are equal, 0 otherwise.
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*/
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static inline int av_cmp_sf_ieee754(SoftFloat_IEEE754 a, SoftFloat_IEEE754 b) {
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a = av_normalize_sf_ieee754(a);
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b = av_normalize_sf_ieee754(b);
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if (a.sign != b.sign) return 0;
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if (a.mant != b.mant) return 0;
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if (a.exp != b.exp ) return 0;
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return 1;
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}
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#endif /*AVUTIL_SOFTFLOAT_IEEE754_H*/
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