## ffmpeg / libavutil / softfloat.h @ 0b006599

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1 | af41dd82 | Diego Biurrun | ```
/*
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2 | ```
* Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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3 | ```
*
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4 | b78e7197 | Diego Biurrun | ```
* This file is part of FFmpeg.
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5 | ```
*
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6 | ```
* FFmpeg is free software; you can redistribute it and/or
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7 | af41dd82 | Diego Biurrun | ```
* modify it under the terms of the GNU Lesser General Public
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8 | ```
* License as published by the Free Software Foundation; either
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9 | b78e7197 | Diego Biurrun | ```
* version 2.1 of the License, or (at your option) any later version.
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10 | af41dd82 | Diego Biurrun | ```
*
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11 | b78e7197 | Diego Biurrun | ```
* FFmpeg is distributed in the hope that it will be useful,
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12 | af41dd82 | Diego Biurrun | ```
* but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | ```
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 | ```
* Lesser General Public License for more details.
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15 | ```
*
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16 | ```
* You should have received a copy of the GNU Lesser General Public
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17 | b78e7197 | Diego Biurrun | ```
* License along with FFmpeg; if not, write to the Free Software
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18 | af41dd82 | Diego Biurrun | ```
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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19 | ```
*
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20 | ```
*/
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21 | a2fd6043 | Michael Niedermayer | |

22 | #define MIN_EXP -126 |
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23 | #define MAX_EXP 126 |
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24 | #define ONE_BITS 29 |
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25 | |||

26 | typedef struct SoftFloat{ |
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27 | int32_t exp; |
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28 | int32_t mant; |
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29 | }SoftFloat; |
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30 | |||

31 | ```
static SoftFloat av_normalize_sf(SoftFloat a){
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32 | ```
if(a.mant){
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33 | #if 1 |
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34 | while((a.mant + 0x20000000U)<0x40000000U){ |
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35 | a.mant += a.mant; |
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36 | ```
a.exp -= 1;
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37 | } |
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38 | ```
#else
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39 | int s=ONE_BITS + 1 - av_log2(a.mant ^ (a.mant<<1)); |
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40 | a.exp -= s; |
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41 | a.mant <<= s; |
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42 | ```
#endif
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43 | ```
if(a.exp < MIN_EXP){
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44 | a.exp = MIN_EXP; |
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45 | ```
a.mant= 0;
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46 | } |
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47 | ```
}else{
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48 | a.exp= MIN_EXP; |
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49 | } |
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50 | ```
return a;
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51 | } |
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52 | |||

53 | static inline SoftFloat av_normalize1_sf(SoftFloat a){ |
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54 | #if 1 |
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55 | if(a.mant + 0x40000000 < 0){ |
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56 | a.exp++; |
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57 | ```
a.mant>>=1;
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58 | } |
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59 | ```
return a;
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60 | #elif 1 |
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61 | int t= a.mant + 0x40000000 < 0; |
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62 | ```
return (SoftFloat){a.exp+t, a.mant>>t};
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63 | ```
#else
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64 | int t= (a.mant + 0x40000000U)>>31; |
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65 | ```
return (SoftFloat){a.exp+t, a.mant>>t};
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66 | ```
#endif
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67 | } |
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68 | |||

69 | ```
/**
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70 | ```
*
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71 | ```
* @return will not be more denormalized then a+b, so if either input is
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72 | ```
* normalized then the output wont be worse then the other input
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73 | ```
* if both are normalized then the output will be normalized
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74 | ```
*/
``` |
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75 | static inline SoftFloat av_mul_sf(SoftFloat a, SoftFloat b){ |
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76 | a.exp += b.exp; |
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77 | a.mant = (a.mant * (int64_t)b.mant) >> ONE_BITS; |
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78 | ```
return av_normalize1_sf(a);
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79 | } |
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80 | |||

81 | ```
/**
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82 | ```
*
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83 | ```
* b has to be normalized and not zero
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84 | ```
* @return will not be more denormalized then a
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85 | ```
*/
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86 | ```
static SoftFloat av_div_sf(SoftFloat a, SoftFloat b){
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87 | ```
a.exp -= b.exp+1;
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88 | ```
a.mant = ((int64_t)a.mant<<(ONE_BITS+1)) / b.mant;
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89 | ```
return av_normalize1_sf(a);
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90 | } |
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91 | |||

92 | static inline int av_cmp_sf(SoftFloat a, SoftFloat b){ |
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93 | ```
int t= a.exp - b.exp;
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94 | if(t<0) return (a.mant >> (-t)) - b.mant ; |
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95 | else return a.mant - (b.mant >> t); |
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96 | } |
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97 | |||

98 | static inline SoftFloat av_add_sf(SoftFloat a, SoftFloat b){ |
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99 | ```
int t= a.exp - b.exp;
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100 | if(t<0) return av_normalize1_sf((SoftFloat){b.exp, b.mant + (a.mant >> (-t))}); |
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101 | else return av_normalize1_sf((SoftFloat){a.exp, a.mant + (b.mant >> t )}); |
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102 | } |
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103 | |||

104 | static inline SoftFloat av_sub_sf(SoftFloat a, SoftFloat b){ |
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105 | ```
return av_add_sf(a, (SoftFloat){b.exp, -b.mant});
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106 | } |
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107 | |||

108 | ```
//FIXME sqrt, log, exp, pow, sin, cos
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109 | |||

110 | static inline SoftFloat av_int2sf(int v, int frac_bits){ |
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111 | ```
return av_normalize_sf((SoftFloat){ONE_BITS-frac_bits, v});
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112 | } |
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113 | |||

114 | ```
/**
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115 | ```
*
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116 | ```
* rounding is to -inf
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117 | ```
*/
``` |
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118 | static inline int av_sf2int(SoftFloat v, int frac_bits){ |
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119 | v.exp += frac_bits - ONE_BITS; |
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120 | if(v.exp >= 0) return v.mant << v.exp ; |
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121 | else return v.mant >>(-v.exp); |
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122 | } |