| 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 */ |