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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 | #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 av_const 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 av_const 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 | * @return Will not be more denormalized than a+b. So if either input is | |
76 | * normalized, then the output will not be worse then the other input. | |
77 | * If both are normalized, then the output will be normalized. | |
78 | */ | |
79 | static inline av_const SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){ | |
80 | a.exp += b.exp; | |
81 | a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS; | |
82 | return av_normalize1_sf(a); | |
83 | } | |
84 | ||
85 | /** | |
86 | * b has to be normalized and not zero. | |
87 | * @return Will not be more denormalized than a. | |
88 | */ | |
89 | static av_const SoftFloat av_div_sf(SoftFloat a, SoftFloat b){ | |
90 | a.exp -= b.exp+1; | |
91 | a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant; | |
92 | return av_normalize1_sf(a); | |
93 | } | |
94 | ||
95 | static inline av_const int av_cmp_sf(SoftFloat a, SoftFloat b){ | |
96 | int t= a.exp - b.exp; | |
97 | if(t<0) return (a.mant >> (-t)) - b.mant ; | |
98 | else return a.mant - (b.mant >> t); | |
99 | } | |
100 | ||
101 | static inline av_const SoftFloat av_add_sf(SoftFloat a, SoftFloat b){ | |
102 | int t= a.exp - b.exp; | |
103 | if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))}); | |
104 | else return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )}); | |
105 | } | |
106 | ||
107 | static inline av_const SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){ | |
108 | return av_add_sf(a, (SoftFloat){b.exp, -b.mant}); | |
109 | } | |
110 | ||
111 | //FIXME sqrt, log, exp, pow, sin, cos | |
112 | ||
113 | static inline av_const SoftFloat av_int2sf(int v, int frac_bits){ | |
114 | return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v}); | |
115 | } | |
116 | ||
117 | /** | |
118 | * Rounding is to -inf. | |
119 | */ | |
120 | static inline av_const int av_sf2int(SoftFloat v, int frac_bits){ | |
121 | v.exp += frac_bits - ONE_BITS; | |
122 | if(v.exp >= 0) return v.mant << v.exp ; | |
123 | else return v.mant >>(-v.exp); | |
124 | } | |
125 | ||
126 | #endif /* AVUTIL_SOFTFLOAT_H */ |