add multiple inclusion guards to headers
[libav.git] / libavutil / softfloat.h
1 /*
2 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 *
20 */
21
22 #ifndef AVUTIL_SOFTFLOAT_H
23 #define AVUTIL_SOFTFLOAT_H
24
25 #include <stdint.h>
26
27 #define MIN_EXP -126
28 #define MAX_EXP 126
29 #define ONE_BITS 29
30
31 typedef struct SoftFloat{
32 int32_t exp;
33 int32_t mant;
34 }SoftFloat;
35
36 static SoftFloat av_normalize_sf(SoftFloat a){
37 if(a.mant){
38 #if 1
39 while((a.mant + 0x20000000U)<0x40000000U){
40 a.mant += a.mant;
41 a.exp -= 1;
42 }
43 #else
44 int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1));
45 a.exp -= s;
46 a.mant <<= s;
47 #endif
48 if(a.exp < MIN_EXP){
49 a.exp = MIN_EXP;
50 a.mant= 0;
51 }
52 }else{
53 a.exp= MIN_EXP;
54 }
55 return a;
56 }
57
58 static inline SoftFloat av_normalize1_sf(SoftFloat a){
59 #if 1
60 if(a.mant + 0x40000000 < 0){
61 a.exp++;
62 a.mant>>=1;
63 }
64 return a;
65 #elif 1
66 int t= a.mant + 0x40000000 < 0;
67 return (SoftFloat){a.exp+t, a.mant>>t};
68 #else
69 int t= (a.mant + 0x40000000U)>>31;
70 return (SoftFloat){a.exp+t, a.mant>>t};
71 #endif
72 }
73
74 /**
75 *
76 * @return will not be more denormalized then a+b, so if either input is
77 * normalized then the output wont be worse then the other input
78 * if both are normalized then the output will be normalized
79 */
80 static inline SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){
81 a.exp += b.exp;
82 a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS;
83 return av_normalize1_sf(a);
84 }
85
86 /**
87 *
88 * b has to be normalized and not zero
89 * @return will not be more denormalized then a
90 */
91 static SoftFloat av_div_sf(SoftFloat a, SoftFloat b){
92 a.exp -= b.exp+1;
93 a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;
94 return av_normalize1_sf(a);
95 }
96
97 static inline int av_cmp_sf(SoftFloat a, SoftFloat b){
98 int t= a.exp - b.exp;
99 if(t<0) return (a.mant >> (-t)) - b.mant ;
100 else return a.mant - (b.mant >> t);
101 }
102
103 static inline SoftFloat av_add_sf(SoftFloat a, SoftFloat b){
104 int t= a.exp - b.exp;
105 if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))});
106 else return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )});
107 }
108
109 static inline SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){
110 return av_add_sf(a, (SoftFloat){b.exp, -b.mant});
111 }
112
113 //FIXME sqrt, log, exp, pow, sin, cos
114
115 static inline SoftFloat av_int2sf(int v, int frac_bits){
116 return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v});
117 }
118
119 /**
120 *
121 * rounding is to -inf
122 */
123 static inline int av_sf2int(SoftFloat v, int frac_bits){
124 v.exp += frac_bits - ONE_BITS;
125 if(v.exp >= 0) return v.mant << v.exp ;
126 else return v.mant >>(-v.exp);
127 }
128
129 #endif