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f4ccf38902
Softfloat will be used in implementation of AAC fixed point decoder. This change is needed in order to more easily integrate ffmpegs softfloat in already developed algorithm for AAC. Signed-off-by: Nedeljko Babic <nedeljko.babic@imgtec.com> Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
133 lines
3.8 KiB
C
133 lines
3.8 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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#define MIN_EXP -126
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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 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 + 0x20000000U)<0x40000000U){
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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 + 1 - av_log2(a.mant ^ (a.mant<<1));
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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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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 + 0x40000000U)>>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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return av_normalize1_sf(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 av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){
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a.exp -= b.exp+1;
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a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;
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return av_normalize1_sf(a);
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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<0) return (a.mant >> (-t)) - b.mant ;
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else return a.mant - (b.mant >> t);
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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_normalize1_sf((SoftFloat){b.mant + (a.mant >> (-t)), b.exp});
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else if (t < 32) return 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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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 sqrt, log, exp, pow, sin, cos
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static inline av_const SoftFloat av_int2sf(int v, int frac_bits){
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return av_normalize_sf((SoftFloat){v, ONE_BITS-frac_bits});
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}
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/**
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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;
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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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#endif /* AVUTIL_SOFTFLOAT_H */
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