mirror of
https://github.com/FFmpeg/FFmpeg.git
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290 lines
8.4 KiB
C
290 lines
8.4 KiB
C
/*
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* Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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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_H
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#define AVUTIL_SOFTFLOAT_H
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#include <stdint.h>
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#include "common.h"
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#include "avassert.h"
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#include "softfloat_tables.h"
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#define MIN_EXP -149
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#define MAX_EXP 126
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#define ONE_BITS 29
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typedef struct SoftFloat{
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int32_t mant;
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int32_t exp;
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}SoftFloat;
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static const SoftFloat FLOAT_0 = { 0, MIN_EXP}; ///< 0.0
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static const SoftFloat FLOAT_05 = { 0x20000000, 0}; ///< 0.5
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static const SoftFloat FLOAT_1 = { 0x20000000, 1}; ///< 1.0
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static const SoftFloat FLOAT_EPSILON = { 0x29F16B12, -16}; ///< A small value
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static const SoftFloat FLOAT_1584893192 = { 0x32B771ED, 1}; ///< 1.584893192 (10^.2)
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static const SoftFloat FLOAT_100000 = { 0x30D40000, 17}; ///< 100000
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static const SoftFloat FLOAT_0999999 = { 0x3FFFFBCE, 0}; ///< 0.999999
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static const SoftFloat FLOAT_MIN = { 0x20000000, MIN_EXP};
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/**
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* Convert a SoftFloat to a double precision float.
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*/
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static inline av_const double av_sf2double(SoftFloat v) {
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v.exp -= ONE_BITS +1;
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return ldexp(v.mant, v.exp);
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}
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static av_const SoftFloat av_normalize_sf(SoftFloat a){
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if(a.mant){
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#if 1
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while((a.mant + 0x1FFFFFFFU)<0x3FFFFFFFU){
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a.mant += a.mant;
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a.exp -= 1;
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}
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#else
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int s=ONE_BITS - av_log2(FFABS(a.mant));
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a.exp -= s;
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a.mant <<= s;
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#endif
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if(a.exp < MIN_EXP){
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a.exp = MIN_EXP;
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a.mant= 0;
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}
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}else{
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a.exp= MIN_EXP;
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}
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return a;
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}
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static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){
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#if 1
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if((int32_t)(a.mant + 0x40000000U) <= 0){
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a.exp++;
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a.mant>>=1;
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}
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av_assert2(a.mant < 0x40000000 && a.mant > -0x40000000);
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av_assert2(a.exp <= MAX_EXP);
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return a;
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#elif 1
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int t= a.mant + 0x40000000 < 0;
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return (SoftFloat){ a.mant>>t, a.exp+t};
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#else
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int t= (a.mant + 0x3FFFFFFFU)>>31;
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return (SoftFloat){a.mant>>t, a.exp+t};
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#endif
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}
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/**
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* @return Will not be more denormalized than a*b. So if either input is
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* normalized, then the output will not be worse then the other input.
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* If both are normalized, then the output will be normalized.
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*/
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static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){
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a.exp += b.exp;
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av_assert2((int32_t)((a.mant * (int64_t)b.mant) >> ONE_BITS) == (a.mant * (int64_t)b.mant) >> ONE_BITS);
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a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;
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a = av_normalize1_sf((SoftFloat){a.mant, a.exp - 1});
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if (!a.mant || a.exp < MIN_EXP)
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return FLOAT_0;
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return a;
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}
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/**
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* b has to be normalized and not zero.
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* @return Will not be more denormalized than a.
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*/
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static inline av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){
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int64_t temp = (int64_t)a.mant * (1<<(ONE_BITS+1));
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temp /= b.mant;
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a.exp -= b.exp;
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a.mant = temp;
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while (a.mant != temp) {
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temp /= 2;
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a.exp--;
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a.mant = temp;
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}
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a = av_normalize1_sf(a);
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if (!a.mant || a.exp < MIN_EXP)
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return FLOAT_0;
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return a;
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}
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/**
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* Compares two SoftFloats.
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* @returns < 0 if the first is less
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* > 0 if the first is greater
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* 0 if they are equal
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*/
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static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){
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int t= a.exp - b.exp;
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if (t <-31) return - b.mant ;
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else if (t < 0) return (a.mant >> (-t)) - b.mant ;
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else if (t < 32) return a.mant - (b.mant >> t);
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else return a.mant ;
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}
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/**
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* Compares two SoftFloats.
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* @returns 1 if a is greater than b, 0 otherwise
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*/
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static inline av_const int av_gt_sf(SoftFloat a, SoftFloat b)
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{
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int t= a.exp - b.exp;
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if (t <-31) return 0 > b.mant ;
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else if (t < 0) return (a.mant >> (-t)) > b.mant ;
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else if (t < 32) return a.mant > (b.mant >> t);
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else return a.mant > 0 ;
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}
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/**
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* @returns the sum of 2 SoftFloats.
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*/
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static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){
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int t= a.exp - b.exp;
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if (t <-31) return b;
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else if (t < 0) return av_normalize_sf(av_normalize1_sf((SoftFloat){ b.mant + (a.mant >> (-t)), b.exp}));
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else if (t < 32) return av_normalize_sf(av_normalize1_sf((SoftFloat){ a.mant + (b.mant >> t ), a.exp}));
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else return a;
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}
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/**
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* @returns the difference of 2 SoftFloats.
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*/
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static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){
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return av_add_sf(a, (SoftFloat){ -b.mant, b.exp});
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}
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//FIXME log, exp, pow
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/**
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* Converts a mantisse and exponent to a SoftFloat.
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* This converts a fixed point value v with frac_bits fractional bits to a
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* SoftFloat.
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* @returns a SoftFloat with value v * 2^-frac_bits
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*/
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static inline av_const SoftFloat av_int2sf(int v, int frac_bits){
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int exp_offset = 0;
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if(v <= INT_MIN + 1){
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exp_offset = 1;
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v>>=1;
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}
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return av_normalize_sf(av_normalize1_sf((SoftFloat){v, ONE_BITS + 1 - frac_bits + exp_offset}));
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}
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/**
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* Converts a SoftFloat to an integer.
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* Rounding is to -inf.
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*/
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static inline av_const int av_sf2int(SoftFloat v, int frac_bits){
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v.exp += frac_bits - (ONE_BITS + 1);
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if(v.exp >= 0) return v.mant << v.exp ;
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else return v.mant >>(-v.exp);
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}
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/**
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* Rounding-to-nearest used.
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*/
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static av_always_inline SoftFloat av_sqrt_sf(SoftFloat val)
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{
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int tabIndex, rem;
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if (val.mant == 0)
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val.exp = MIN_EXP;
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else if (val.mant < 0)
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abort();
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else
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{
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tabIndex = (val.mant - 0x20000000) >> 20;
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rem = val.mant & 0xFFFFF;
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val.mant = (int)(((int64_t)av_sqrttbl_sf[tabIndex] * (0x100000 - rem) +
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(int64_t)av_sqrttbl_sf[tabIndex + 1] * rem +
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0x80000) >> 20);
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val.mant = (int)(((int64_t)av_sqr_exp_multbl_sf[val.exp & 1] * val.mant +
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0x10000000) >> 29);
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if (val.mant < 0x40000000)
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val.exp -= 2;
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else
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val.mant >>= 1;
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val.exp = (val.exp >> 1) + 1;
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}
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return val;
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}
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/**
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* Rounding-to-nearest used.
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*/
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static av_unused void av_sincos_sf(int a, int *s, int *c)
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{
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int idx, sign;
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int sv, cv;
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int st, ct;
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idx = a >> 26;
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sign = (int32_t)((unsigned)idx << 27) >> 31;
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cv = av_costbl_1_sf[idx & 0xf];
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cv = (cv ^ sign) - sign;
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idx -= 8;
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sign = (int32_t)((unsigned)idx << 27) >> 31;
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sv = av_costbl_1_sf[idx & 0xf];
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sv = (sv ^ sign) - sign;
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idx = a >> 21;
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ct = av_costbl_2_sf[idx & 0x1f];
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st = av_sintbl_2_sf[idx & 0x1f];
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idx = (int)(((int64_t)cv * ct - (int64_t)sv * st + 0x20000000) >> 30);
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sv = (int)(((int64_t)cv * st + (int64_t)sv * ct + 0x20000000) >> 30);
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cv = idx;
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idx = a >> 16;
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ct = av_costbl_3_sf[idx & 0x1f];
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st = av_sintbl_3_sf[idx & 0x1f];
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idx = (int)(((int64_t)cv * ct - (int64_t)sv * st + 0x20000000) >> 30);
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sv = (int)(((int64_t)cv * st + (int64_t)sv * ct + 0x20000000) >> 30);
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cv = idx;
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idx = a >> 11;
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ct = (int)(((int64_t)av_costbl_4_sf[idx & 0x1f] * (0x800 - (a & 0x7ff)) +
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(int64_t)av_costbl_4_sf[(idx & 0x1f)+1]*(a & 0x7ff) +
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0x400) >> 11);
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st = (int)(((int64_t)av_sintbl_4_sf[idx & 0x1f] * (0x800 - (a & 0x7ff)) +
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(int64_t)av_sintbl_4_sf[(idx & 0x1f) + 1] * (a & 0x7ff) +
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0x400) >> 11);
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*c = (int)(((int64_t)cv * ct + (int64_t)sv * st + 0x20000000) >> 30);
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*s = (int)(((int64_t)cv * st + (int64_t)sv * ct + 0x20000000) >> 30);
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}
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#endif /* AVUTIL_SOFTFLOAT_H */
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