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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"
#include "softfloat_tables.h"
#define MIN_EXP -126
#define MAX_EXP 126
#define ONE_BITS 29
typedef struct SoftFloat{
int32_t mant;
int32_t exp;
}SoftFloat;
static av_const SoftFloat av_normalize_sf(SoftFloat a){
if(a.mant){
#if 1
while((a.mant + 0x1FFFFFFFU)<0x3FFFFFFFU){
a.mant += a.mant;
a.exp -= 1;
}
#else
int s=ONE_BITS - av_log2(FFABS(a.mant));
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.mant>>t, a.exp+t};
#else
int t= (a.mant + 0x3FFFFFFFU)>>31;
return (SoftFloat){a.mant>>t, a.exp+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((SoftFloat){a.mant, a.exp - 1});
}
/**
* 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;
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 int av_gt_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_normalize_sf(av_normalize1_sf((SoftFloat){ b.mant + (a.mant >> (-t)), b.exp}));
else if (t < 32) return av_normalize_sf(av_normalize1_sf((SoftFloat){ a.mant + (b.mant >> t ), a.exp}));
else return a;
}
static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){
return av_add_sf(a, (SoftFloat){ -b.mant, b.exp});
}
//FIXME log, exp, pow
/**
* Converts a mantisse and exponent to a SoftFloat
* @returns a SoftFloat with value v * 2^frac_bits
*/
static inline av_const SoftFloat av_int2sf(int v, int frac_bits){
return av_normalize_sf((SoftFloat){v, ONE_BITS + 1 - frac_bits});
}
/**
* Rounding is to -inf.
*/
static inline av_const int av_sf2int(SoftFloat v, int frac_bits){
v.exp += frac_bits - (ONE_BITS + 1);
if(v.exp >= 0) return v.mant << v.exp ;
else return v.mant >>(-v.exp);
}
/**
* Rounding-to-nearest used.
*/
static av_always_inline SoftFloat av_sqrt_sf(SoftFloat val)
{
int tabIndex, rem;
if (val.mant == 0)
val.exp = 0;
else
{
tabIndex = (val.mant - 0x20000000) >> 20;
rem = val.mant & 0xFFFFF;
val.mant = (int)(((int64_t)av_sqrttbl_sf[tabIndex] * (0x100000 - rem) +
(int64_t)av_sqrttbl_sf[tabIndex + 1] * rem +
0x80000) >> 20);
val.mant = (int)(((int64_t)av_sqr_exp_multbl_sf[val.exp & 1] * val.mant +
0x10000000) >> 29);
if (val.mant < 0x40000000)
val.exp -= 2;
else
val.mant >>= 1;
val.exp = (val.exp >> 1) + 1;
}
return val;
}
/**
* Rounding-to-nearest used.
*/
void av_sincos_sf(int a, int *s, int *c);
#endif /* AVUTIL_SOFTFLOAT_H */
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