mathematics.h (3406B)
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 #include "intfloat.h" 29 30 #ifndef M_LOG2_10 31 #define M_LOG2_10 3.32192809488736234787 /* log_2 10 */ 32 #endif 33 #ifndef M_PHI 34 #define M_PHI 1.61803398874989484820 /* phi / golden ratio */ 35 #endif 36 #ifndef NAN 37 #define NAN av_int2float(0x7fc00000) 38 #endif 39 #ifndef INFINITY 40 #define INFINITY av_int2float(0x7f800000) 41 #endif 42 43 /** 44 * @addtogroup lavu_math 45 * @{ 46 */ 47 48 49 enum AVRounding { 50 AV_ROUND_ZERO = 0, ///< Round toward zero. 51 AV_ROUND_INF = 1, ///< Round away from zero. 52 AV_ROUND_DOWN = 2, ///< Round toward -infinity. 53 AV_ROUND_UP = 3, ///< Round toward +infinity. 54 AV_ROUND_NEAR_INF = 5, ///< Round to nearest and halfway cases away from zero. 55 }; 56 57 /** 58 * Return the greatest common divisor of a and b. 59 * If both a and b are 0 or either or both are <0 then behavior is 60 * undefined. 61 */ 62 int64_t av_const av_gcd(int64_t a, int64_t b); 63 64 /** 65 * Rescale a 64-bit integer with rounding to nearest. 66 * A simple a*b/c isn't possible as it can overflow. 67 */ 68 int64_t av_rescale(int64_t a, int64_t b, int64_t c) av_const; 69 70 /** 71 * Rescale a 64-bit integer with specified rounding. 72 * A simple a*b/c isn't possible as it can overflow. 73 */ 74 int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_const; 75 76 /** 77 * Rescale a 64-bit integer by 2 rational numbers. 78 */ 79 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const; 80 81 /** 82 * Rescale a 64-bit integer by 2 rational numbers with specified rounding. 83 */ 84 int64_t av_rescale_q_rnd(int64_t a, AVRational bq, AVRational cq, 85 enum AVRounding) av_const; 86 87 /** 88 * Compare 2 timestamps each in its own timebases. 89 * The result of the function is undefined if one of the timestamps 90 * is outside the int64_t range when represented in the others timebase. 91 * @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 92 */ 93 int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b); 94 95 /** 96 * Compare 2 integers modulo mod. 97 * That is we compare integers a and b for which only the least 98 * significant log2(mod) bits are known. 99 * 100 * @param mod must be a power of 2 101 * @return a negative value if a is smaller than b 102 * a positive value if a is greater than b 103 * 0 if a equals b 104 */ 105 int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod); 106 107 /** 108 * @} 109 */ 110 111 #endif /* AVUTIL_MATHEMATICS_H */