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| 4349 | Serge | 1 | /* |
| 2 | * rational numbers |
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| 3 | * Copyright (c) 2003 Michael Niedermayer |
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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 | |||
| 22 | /** |
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| 23 | * @file |
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| 24 | * rational numbers |
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| 25 | * @author Michael Niedermayer |
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| 26 | */ |
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| 27 | |||
| 28 | #ifndef AVUTIL_RATIONAL_H |
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| 29 | #define AVUTIL_RATIONAL_H |
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| 30 | |||
| 31 | #include |
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| 32 | #include |
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| 33 | #include "attributes.h" |
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| 34 | |||
| 35 | /** |
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| 36 | * @addtogroup lavu_math |
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| 37 | * @{ |
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| 38 | */ |
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| 39 | |||
| 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 | |||
| 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 |
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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 | |||
| 58 | if(tmp) return (int)((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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 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 | |||
| 151 | /** |
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| 152 | * @} |
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| 153 | */ |
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| 154 | |||
| 155 | #endif /* AVUTIL_RATIONAL_H */ |