Mercurial > hg > forks > libbpg
comparison libavutil/softfloat.h @ 0:772086c29cc7
Initial import.
author | Matti Hamalainen <ccr@tnsp.org> |
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date | Wed, 16 Nov 2016 11:16:33 +0200 |
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-1:000000000000 | 0:772086c29cc7 |
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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 #ifndef AVUTIL_SOFTFLOAT_H | |
22 #define AVUTIL_SOFTFLOAT_H | |
23 | |
24 #include <stdint.h> | |
25 #include "common.h" | |
26 | |
27 #include "avassert.h" | |
28 | |
29 #define MIN_EXP -126 | |
30 #define MAX_EXP 126 | |
31 #define ONE_BITS 29 | |
32 | |
33 typedef struct SoftFloat{ | |
34 int32_t exp; | |
35 int32_t mant; | |
36 }SoftFloat; | |
37 | |
38 static av_const SoftFloat av_normalize_sf(SoftFloat a){ | |
39 if(a.mant){ | |
40 #if 1 | |
41 while((a.mant + 0x20000000U)<0x40000000U){ | |
42 a.mant += a.mant; | |
43 a.exp -= 1; | |
44 } | |
45 #else | |
46 int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1)); | |
47 a.exp -= s; | |
48 a.mant <<= s; | |
49 #endif | |
50 if(a.exp < MIN_EXP){ | |
51 a.exp = MIN_EXP; | |
52 a.mant= 0; | |
53 } | |
54 }else{ | |
55 a.exp= MIN_EXP; | |
56 } | |
57 return a; | |
58 } | |
59 | |
60 static inline av_const SoftFloat av_normalize1_sf(SoftFloat a){ | |
61 #if 1 | |
62 if((int32_t)(a.mant + 0x40000000U) < 0){ | |
63 a.exp++; | |
64 a.mant>>=1; | |
65 } | |
66 av_assert2(a.mant < 0x40000000 && a.mant > -0x40000000); | |
67 return a; | |
68 #elif 1 | |
69 int t= a.mant + 0x40000000 < 0; | |
70 return (SoftFloat){a.exp+t, a.mant>>t}; | |
71 #else | |
72 int t= (a.mant + 0x40000000U)>>31; | |
73 return (SoftFloat){a.exp+t, a.mant>>t}; | |
74 #endif | |
75 } | |
76 | |
77 /** | |
78 * @return Will not be more denormalized than a+b. So if either input is | |
79 * normalized, then the output will not be worse then the other input. | |
80 * If both are normalized, then the output will be normalized. | |
81 */ | |
82 static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){ | |
83 a.exp += b.exp; | |
84 av_assert2((int32_t)((a.mant * (int64_t)b.mant) >> ONE_BITS) == (a.mant * (int64_t)b.mant) >> ONE_BITS); | |
85 a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS; | |
86 return av_normalize1_sf(a); | |
87 } | |
88 | |
89 /** | |
90 * b has to be normalized and not zero. | |
91 * @return Will not be more denormalized than a. | |
92 */ | |
93 static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){ | |
94 a.exp -= b.exp+1; | |
95 a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant; | |
96 return av_normalize1_sf(a); | |
97 } | |
98 | |
99 static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){ | |
100 int t= a.exp - b.exp; | |
101 if(t<0) return (a.mant >> (-t)) - b.mant ; | |
102 else return a.mant - (b.mant >> t); | |
103 } | |
104 | |
105 static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){ | |
106 int t= a.exp - b.exp; | |
107 if (t <-31) return b; | |
108 else if (t < 0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))}); | |
109 else if (t < 32) return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )}); | |
110 else return a; | |
111 } | |
112 | |
113 static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){ | |
114 return av_add_sf(a, (SoftFloat){b.exp, -b.mant}); | |
115 } | |
116 | |
117 //FIXME sqrt, log, exp, pow, sin, cos | |
118 | |
119 static inline av_const SoftFloat av_int2sf(int v, int frac_bits){ | |
120 return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v}); | |
121 } | |
122 | |
123 /** | |
124 * Rounding is to -inf. | |
125 */ | |
126 static inline av_const int av_sf2int(SoftFloat v, int frac_bits){ | |
127 v.exp += frac_bits - ONE_BITS; | |
128 if(v.exp >= 0) return v.mant << v.exp ; | |
129 else return v.mant >>(-v.exp); | |
130 } | |
131 | |
132 #endif /* AVUTIL_SOFTFLOAT_H */ |