mathematics.h (5227B)
1 /* 2 * copyright (c) 2005-2012 Michael Niedermayer <michaelni@gmx.at> 3 * 4 * This file is part of FFmpeg. 5 * 6 * FFmpeg 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 * FFmpeg 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 FFmpeg; 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 #include "intfloat.h" 29 30 #ifndef M_E 31 #define M_E 2.7182818284590452354 /* e */ 32 #endif 33 #ifndef M_LN2 34 #define M_LN2 0.69314718055994530942 /* log_e 2 */ 35 #endif 36 #ifndef M_LN10 37 #define M_LN10 2.30258509299404568402 /* log_e 10 */ 38 #endif 39 #ifndef M_LOG2_10 40 #define M_LOG2_10 3.32192809488736234787 /* log_2 10 */ 41 #endif 42 #ifndef M_PHI 43 #define M_PHI 1.61803398874989484820 /* phi / golden ratio */ 44 #endif 45 #ifndef M_PI 46 #define M_PI 3.14159265358979323846 /* pi */ 47 #endif 48 #ifndef M_PI_2 49 #define M_PI_2 1.57079632679489661923 /* pi/2 */ 50 #endif 51 #ifndef M_SQRT1_2 52 #define M_SQRT1_2 0.70710678118654752440 /* 1/sqrt(2) */ 53 #endif 54 #ifndef M_SQRT2 55 #define M_SQRT2 1.41421356237309504880 /* sqrt(2) */ 56 #endif 57 #ifndef NAN 58 #define NAN av_int2float(0x7fc00000) 59 #endif 60 #ifndef INFINITY 61 #define INFINITY av_int2float(0x7f800000) 62 #endif 63 64 /** 65 * @addtogroup lavu_math 66 * @{ 67 */ 68 69 70 enum AVRounding { 71 AV_ROUND_ZERO = 0, ///< Round toward zero. 72 AV_ROUND_INF = 1, ///< Round away from zero. 73 AV_ROUND_DOWN = 2, ///< Round toward -infinity. 74 AV_ROUND_UP = 3, ///< Round toward +infinity. 75 AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero. 76 AV_ROUND_PASS_MINMAX = 8192, ///< Flag to pass INT64_MIN/MAX through instead of rescaling, this avoids special cases for AV_NOPTS_VALUE 77 }; 78 79 /** 80 * Compute the greatest common divisor of a and b. 81 * 82 * @return gcd of a and b up to sign; if a >= 0 and b >= 0, return value is >= 0; 83 * if a == 0 and b == 0, returns 0. 84 */ 85 int64_t av_const av_gcd(int64_t a, int64_t b); 86 87 /** 88 * Rescale a 64-bit integer with rounding to nearest. 89 * A simple a*b/c isn't possible as it can overflow. 90 */ 91 int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const; 92 93 /** 94 * Rescale a 64-bit integer with specified rounding. 95 * A simple a*b/c isn't possible as it can overflow. 96 * 97 * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is 98 * INT64_MIN or INT64_MAX then a is passed through unchanged. 99 */ 100 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const; 101 102 /** 103 * Rescale a 64-bit integer by 2 rational numbers. 104 */ 105 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const; 106 107 /** 108 * Rescale a 64-bit integer by 2 rational numbers with specified rounding. 109 * 110 * @return rescaled value a, or if AV_ROUND_PASS_MINMAX is set and a is 111 * INT64_MIN or INT64_MAX then a is passed through unchanged. 112 */ 113 int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq, 114 enum AVRounding) av_const; 115 116 /** 117 * Compare 2 timestamps each in its own timebases. 118 * The result of the function is undefined if one of the timestamps 119 * is outside the int64_t range when represented in the others timebase. 120 * @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 121 */ 122 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b); 123 124 /** 125 * Compare 2 integers modulo mod. 126 * That is we compare integers a and b for which only the least 127 * significant log2(mod) bits are known. 128 * 129 * @param mod must be a power of 2 130 * @return a negative value if a is smaller than b 131 * a positive value if a is greater than b 132 * 0 if a equals b 133 */ 134 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod); 135 136 /** 137 * Rescale a timestamp while preserving known durations. 138 * 139 * @param in_ts Input timestamp 140 * @param in_tb Input timebase 141 * @param fs_tb Duration and *last timebase 142 * @param duration duration till the next call 143 * @param out_tb Output timebase 144 */ 145 int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb); 146 147 /** 148 * Add a value to a timestamp. 149 * 150 * This function guarantees that when the same value is repeatly added that 151 * no accumulation of rounding errors occurs. 152 * 153 * @param ts Input timestamp 154 * @param ts_tb Input timestamp timebase 155 * @param inc value to add to ts 156 * @param inc_tb inc timebase 157 */ 158 int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc); 159 160 161 /** 162 * @} 163 */ 164 165 #endif /* AVUTIL_MATHEMATICS_H */