summaryrefslogtreecommitdiffstats
path: root/libavutil/softfloat.h
blob: 97e09ea7e7ac4842aa07aed8d427711fadaf2c31 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
/*
 * 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"

#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(a.mant + 0x40000000 < 0){
        a.exp++;
        a.mant>>=1;
    }
    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;
    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<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))});
    else    return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >>   t )});
}

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 */
OpenPOWER on IntegriCloud