mathematics.h (3640B)
1 /* 2 * copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at> 3 * 4 * This file is part of Libav. 5 * 6 * Libav 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 * Libav 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 Libav; 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_MATHEMATICS_H 22 #define AVUTIL_MATHEMATICS_H 23 24 #include <stdint.h> 25 #include <math.h> 26 #include "attributes.h" 27 #include "rational.h" 28 29 #ifndef M_E 30 #define M_E 2.7182818284590452354 /* e */ 31 #endif 32 #ifndef M_LN2 33 #define M_LN2 0.69314718055994530942 /* log_e 2 */ 34 #endif 35 #ifndef M_LN10 36 #define M_LN10 2.30258509299404568402 /* log_e 10 */ 37 #endif 38 #ifndef M_LOG2_10 39 #define M_LOG2_10 3.32192809488736234787 /* log_2 10 */ 40 #endif 41 #ifndef M_PHI 42 #define M_PHI 1.61803398874989484820 /* phi / golden ratio */ 43 #endif 44 #ifndef M_PI 45 #define M_PI 3.14159265358979323846 /* pi */ 46 #endif 47 #ifndef M_SQRT1_2 48 #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */ 49 #endif 50 #ifndef M_SQRT2 51 #define M_SQRT2 1.41421356237309504880 /* sqrt(2) */ 52 #endif 53 #ifndef NAN 54 #define NAN (0.0/0.0) 55 #endif 56 #ifndef INFINITY 57 #define INFINITY (1.0/0.0) 58 #endif 59 60 /** 61 * @addtogroup lavu_math 62 * @{ 63 */ 64 65 66 enum AVRounding { 67 AV_ROUND_ZERO = 0, ///< Round toward zero. 68 AV_ROUND_INF = 1, ///< Round away from zero. 69 AV_ROUND_DOWN = 2, ///< Round toward -infinity. 70 AV_ROUND_UP = 3, ///< Round toward +infinity. 71 AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero. 72 }; 73 74 /** 75 * Return the greatest common divisor of a and b. 76 * If both a and b are 0 or either or both are <0 then behavior is 77 * undefined. 78 */ 79 int64_t av_const av_gcd(int64_t a, int64_t b); 80 81 /** 82 * Rescale a 64-bit integer with rounding to nearest. 83 * A simple a*b/c isn't possible as it can overflow. 84 */ 85 int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const; 86 87 /** 88 * Rescale a 64-bit integer with specified rounding. 89 * A simple a*b/c isn't possible as it can overflow. 90 */ 91 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const; 92 93 /** 94 * Rescale a 64-bit integer by 2 rational numbers. 95 */ 96 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const; 97 98 /** 99 * Compare 2 timestamps each in its own timebases. 100 * The result of the function is undefined if one of the timestamps 101 * is outside the int64_t range when represented in the others timebase. 102 * @return -1 if ts_a is before ts_b, 1 if ts_a is after ts_b or 0 if they represent the same position 103 */ 104 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b); 105 106 /** 107 * Compare 2 integers modulo mod. 108 * That is we compare integers a and b for which only the least 109 * significant log2(mod) bits are known. 110 * 111 * @param mod must be a power of 2 112 * @return a negative value if a is smaller than b 113 * a positive value if a is greater than b 114 * 0 if a equals b 115 */ 116 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod); 117 118 /** 119 * @} 120 */ 121 122 #endif /* AVUTIL_MATHEMATICS_H */