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/*
* Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_SOFTFLOAT_H
#define AVUTIL_SOFTFLOAT_H
#include <stdint.h>
#include "common.h"
#include "avassert.h"
#define MIN_EXP -126
#define MAX_EXP 126
#define ONE_BITS 29
typedef struct SoftFloat{
int32_t exp;
int32_t mant;
}SoftFloat;
static av_const SoftFloat av_normalize_sf(SoftFloat a){
if(a.mant){
#if 1
while((a.mant + 0x20000000U)<0x40000000U){
a.mant += a.mant;
a.exp -= 1;
}
#else
int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1));
a.exp -= s;
a.mant <<= s;
#endif
if(a.exp < MIN_EXP){
a.exp = MIN_EXP;
a.mant= 0;
}
}else{
a.exp= MIN_EXP;
}
return a;
}
static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){
#if 1
if((int32_t)(a.mant + 0x40000000U) <= 0){
a.exp++;
a.mant>>=1;
}
av_assert2(a.mant < 0x40000000 && a.mant > -0x40000000);
return a;
#elif 1
int t= a.mant + 0x40000000 < 0;
return (SoftFloat){a.exp+t, a.mant>>t};
#else
int t= (a.mant + 0x40000000U)>>31;
return (SoftFloat){a.exp+t, a.mant>>t};
#endif
}
/**
* @return Will not be more denormalized than a+b. So if either input is
* normalized, then the output will not be worse then the other input.
* If both are normalized, then the output will be normalized.
*/
static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){
a.exp += b.exp;
av_assert2((int32_t)((a.mant * (int64_t)b.mant) >> ONE_BITS) == (a.mant * (int64_t)b.mant) >> ONE_BITS);
a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;
return av_normalize1_sf(a);
}
/**
* b has to be normalized and not zero.
* @return Will not be more denormalized than a.
*/
static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){
a.exp -= b.exp+1;
a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;
return av_normalize1_sf(a);
}
static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){
int t= a.exp - b.exp;
if(t<0) return (a.mant >> (-t)) - b.mant ;
else return a.mant - (b.mant >> t);
}
static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){
int t= a.exp - b.exp;
if (t <-31) return b;
else if (t < 0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))});
else if (t < 32) return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )});
else return a;
}
static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){
return av_add_sf(a, (SoftFloat){b.exp, -b.mant});
}
//FIXME sqrt, log, exp, pow, sin, cos
static inline av_const SoftFloat av_int2sf(int v, int frac_bits){
return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v});
}
/**
* Rounding is to -inf.
*/
static inline av_const int av_sf2int(SoftFloat v, int frac_bits){
v.exp += frac_bits - ONE_BITS;
if(v.exp >= 0) return v.mant << v.exp ;
else return v.mant >>(-v.exp);
}
#endif /* AVUTIL_SOFTFLOAT_H */
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