| 1 | /* |
| 2 | * rational numbers |
| 3 | * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at> |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | /** |
| 23 | * @file |
| 24 | * rational numbers |
| 25 | * @author Michael Niedermayer <michaelni@gmx.at> |
| 26 | */ |
| 27 | |
| 28 | #ifndef AVUTIL_RATIONAL_H |
| 29 | #define AVUTIL_RATIONAL_H |
| 30 | |
| 31 | #include <stdint.h> |
| 32 | #include <limits.h> |
| 33 | #include "attributes.h" |
| 34 | |
| 35 | /** |
| 36 | * @addtogroup lavu_math |
| 37 | * @{ |
| 38 | */ |
| 39 | |
| 40 | /** |
| 41 | * rational number numerator/denominator |
| 42 | */ |
| 43 | typedef struct AVRational{ |
| 44 | int num; ///< numerator |
| 45 | int den; ///< denominator |
| 46 | } AVRational; |
| 47 | |
| 48 | /** |
| 49 | * Create a rational. |
| 50 | * Useful for compilers that do not support compound literals. |
| 51 | * @note The return value is not reduced. |
| 52 | */ |
| 53 | static inline AVRational av_make_q(int num, int den) |
| 54 | { |
| 55 | AVRational r = { num, den }; |
| 56 | return r; |
| 57 | } |
| 58 | |
| 59 | /** |
| 60 | * Compare two rationals. |
| 61 | * @param a first rational |
| 62 | * @param b second rational |
| 63 | * @return 0 if a==b, 1 if a>b, -1 if a<b, and INT_MIN if one of the |
| 64 | * values is of the form 0/0 |
| 65 | */ |
| 66 | static inline int av_cmp_q(AVRational a, AVRational b){ |
| 67 | const int64_t tmp= a.num * (int64_t)b.den - b.num * (int64_t)a.den; |
| 68 | |
| 69 | if(tmp) return (int)((tmp ^ a.den ^ b.den)>>63)|1; |
| 70 | else if(b.den && a.den) return 0; |
| 71 | else if(a.num && b.num) return (a.num>>31) - (b.num>>31); |
| 72 | else return INT_MIN; |
| 73 | } |
| 74 | |
| 75 | /** |
| 76 | * Convert rational to double. |
| 77 | * @param a rational to convert |
| 78 | * @return (double) a |
| 79 | */ |
| 80 | static inline double av_q2d(AVRational a){ |
| 81 | return a.num / (double) a.den; |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * Reduce a fraction. |
| 86 | * This is useful for framerate calculations. |
| 87 | * @param dst_num destination numerator |
| 88 | * @param dst_den destination denominator |
| 89 | * @param num source numerator |
| 90 | * @param den source denominator |
| 91 | * @param max the maximum allowed for dst_num & dst_den |
| 92 | * @return 1 if exact, 0 otherwise |
| 93 | */ |
| 94 | int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max); |
| 95 | |
| 96 | /** |
| 97 | * Multiply two rationals. |
| 98 | * @param b first rational |
| 99 | * @param c second rational |
| 100 | * @return b*c |
| 101 | */ |
| 102 | AVRational av_mul_q(AVRational b, AVRational c) av_const; |
| 103 | |
| 104 | /** |
| 105 | * Divide one rational by another. |
| 106 | * @param b first rational |
| 107 | * @param c second rational |
| 108 | * @return b/c |
| 109 | */ |
| 110 | AVRational av_div_q(AVRational b, AVRational c) av_const; |
| 111 | |
| 112 | /** |
| 113 | * Add two rationals. |
| 114 | * @param b first rational |
| 115 | * @param c second rational |
| 116 | * @return b+c |
| 117 | */ |
| 118 | AVRational av_add_q(AVRational b, AVRational c) av_const; |
| 119 | |
| 120 | /** |
| 121 | * Subtract one rational from another. |
| 122 | * @param b first rational |
| 123 | * @param c second rational |
| 124 | * @return b-c |
| 125 | */ |
| 126 | AVRational av_sub_q(AVRational b, AVRational c) av_const; |
| 127 | |
| 128 | /** |
| 129 | * Invert a rational. |
| 130 | * @param q value |
| 131 | * @return 1 / q |
| 132 | */ |
| 133 | static av_always_inline AVRational av_inv_q(AVRational q) |
| 134 | { |
| 135 | AVRational r = { q.den, q.num }; |
| 136 | return r; |
| 137 | } |
| 138 | |
| 139 | /** |
| 140 | * Convert a double precision floating point number to a rational. |
| 141 | * inf is expressed as {1,0} or {-1,0} depending on the sign. |
| 142 | * |
| 143 | * @param d double to convert |
| 144 | * @param max the maximum allowed numerator and denominator |
| 145 | * @return (AVRational) d |
| 146 | */ |
| 147 | AVRational av_d2q(double d, int max) av_const; |
| 148 | |
| 149 | /** |
| 150 | * @return 1 if q1 is nearer to q than q2, -1 if q2 is nearer |
| 151 | * than q1, 0 if they have the same distance. |
| 152 | */ |
| 153 | int av_nearer_q(AVRational q, AVRational q1, AVRational q2); |
| 154 | |
| 155 | /** |
| 156 | * Find the nearest value in q_list to q. |
| 157 | * @param q_list an array of rationals terminated by {0, 0} |
| 158 | * @return the index of the nearest value found in the array |
| 159 | */ |
| 160 | int av_find_nearest_q_idx(AVRational q, const AVRational* q_list); |
| 161 | |
| 162 | /** |
| 163 | * @} |
| 164 | */ |
| 165 | |
| 166 | #endif /* AVUTIL_RATIONAL_H */ |