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2134
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1 /*
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2 * rational numbers
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3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
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4 *
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5 * This file is part of FFmpeg.
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6 *
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7 * FFmpeg is free software; you can redistribute it and/or
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8 * modify it under the terms of the GNU Lesser General Public
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9 * License as published by the Free Software Foundation; either
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10 * version 2.1 of the License, or (at your option) any later version.
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11 *
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12 * FFmpeg is distributed in the hope that it will be useful,
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13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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15 * Lesser General Public License for more details.
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16 *
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17 * You should have received a copy of the GNU Lesser General Public
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18 * License along with FFmpeg; if not, write to the Free Software
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19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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20 */
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21
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22 /**
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23 * @file
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24 * rational numbers
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25 * @author Michael Niedermayer <michaelni@gmx.at>
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26 */
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27
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28 #ifndef AVUTIL_RATIONAL_H
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29 #define AVUTIL_RATIONAL_H
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30
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31 #include <stdint.h>
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32 #include <limits.h>
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33 #include "attributes.h"
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34
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35 /**
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36 * @addtogroup lavu_math
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37 * @{
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38 */
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39
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40 /**
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41 * rational number numerator/denominator
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42 */
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43 typedef struct AVRational{
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44 int num; ///< numerator
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45 int den; ///< denominator
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46 } AVRational;
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47
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48 /**
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49 * Compare two rationals.
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50 * @param a first rational
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51 * @param b second rational
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52 * @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the
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53 * values is of the form 0/0
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54 */
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55 static inline int av_cmp_q(AVRational a, AVRational b){
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56 const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den;
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57
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58 if(tmp) return ((tmp ^ a.den ^ b.den)>>63)|1;
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59 else if(b.den && a.den) return 0;
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60 else if(a.num && b.num) return (a.num>>31) - (b.num>>31);
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61 else return INT_MIN;
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62 }
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63
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64 /**
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65 * Convert rational to double.
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66 * @param a rational to convert
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67 * @return (double) a
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68 */
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69 static inline double av_q2d(AVRational a){
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70 return a.num / (double) a.den;
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71 }
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72
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73 /**
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74 * Reduce a fraction.
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75 * This is useful for framerate calculations.
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76 * @param dst_num destination numerator
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77 * @param dst_den destination denominator
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78 * @param num source numerator
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79 * @param den source denominator
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80 * @param max the maximum allowed for dst_num & dst_den
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81 * @return 1 if exact, 0 otherwise
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82 */
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83 int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
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84
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85 /**
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86 * Multiply two rationals.
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87 * @param b first rational
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88 * @param c second rational
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89 * @return b*c
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90 */
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91 AVRational av_mul_q(AVRational b, AVRational c) av_const;
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92
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93 /**
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94 * Divide one rational by another.
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95 * @param b first rational
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96 * @param c second rational
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97 * @return b/c
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98 */
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99 AVRational av_div_q(AVRational b, AVRational c) av_const;
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100
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101 /**
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102 * Add two rationals.
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103 * @param b first rational
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104 * @param c second rational
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105 * @return b+c
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106 */
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107 AVRational av_add_q(AVRational b, AVRational c) av_const;
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108
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109 /**
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110 * Subtract one rational from another.
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111 * @param b first rational
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112 * @param c second rational
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113 * @return b-c
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114 */
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115 AVRational av_sub_q(AVRational b, AVRational c) av_const;
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116
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117 /**
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118 * Invert a rational.
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119 * @param q value
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120 * @return 1 / q
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121 */
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122 static av_always_inline AVRational av_inv_q(AVRational q)
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123 {
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124 AVRational r = { q.den, q.num };
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125 return r;
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126 }
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127
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128 /**
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129 * Convert a double precision floating point number to a rational.
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130 * inf is expressed as {1,0} or {-1,0} depending on the sign.
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131 *
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132 * @param d double to convert
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133 * @param max the maximum allowed numerator and denominator
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134 * @return (AVRational) d
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135 */
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136 AVRational av_d2q(double d, int max) av_const;
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137
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138 /**
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139 * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer
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140 * than q1, 0 if they have the same distance.
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141 */
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142 int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
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143
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144 /**
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145 * Find the nearest value in q_list to q.
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146 * @param q_list an array of rationals terminated by {0, 0}
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147 * @return the index of the nearest value found in the array
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148 */
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149 int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
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150
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151 /**
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152 * @}
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153 */
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154
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155 #endif /* AVUTIL_RATIONAL_H */
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