1/* 2 * Copyright (c) 2002 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/** 22 * @file 23 * simple arithmetic expression evaluator 24 */ 25 26#ifndef AVCODEC_EVAL_H 27#define AVCODEC_EVAL_H 28 29typedef struct AVExpr AVExpr; 30 31/** 32 * Parses and evaluates an expression. 33 * Note, this is significantly slower than ff_eval_expr(). 34 * 35 * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)" 36 * @param func1 NULL terminated array of function pointers for functions which take 1 argument 37 * @param func2 NULL terminated array of function pointers for functions which take 2 arguments 38 * @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0} 39 * @param func1_name NULL terminated array of zero terminated strings of func1 identifers 40 * @param func2_name NULL terminated array of zero terminated strings of func2 identifers 41 * @param error pointer to a char* which is set to an error message if something goes wrong 42 * @param const_value a zero terminated array of values for the identifers from const_name 43 * @param opaque a pointer which will be passed to all functions from func1 and func2 44 * @return the value of the expression 45 */ 46double ff_parse_and_eval_expr(const char *s, const double *const_value, const char * const *const_name, 47 double (* const *func1)(void *, double), const char * const *func1_name, 48 double (* const *func2)(void *, double, double), const char * const *func2_name, 49 void *opaque, const char **error); 50 51/** 52 * Parses an expression. 53 * 54 * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)" 55 * @param func1 NULL terminated array of function pointers for functions which take 1 argument 56 * @param func2 NULL terminated array of function pointers for functions which take 2 arguments 57 * @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0} 58 * @param func1_name NULL terminated array of zero terminated strings of func1 identifers 59 * @param func2_name NULL terminated array of zero terminated strings of func2 identifers 60 * @param error pointer to a char* which is set to an error message if something goes wrong 61 * @return AVExpr which must be freed with ff_free_expr() by the user when it is not needed anymore 62 * NULL if anything went wrong 63 */ 64AVExpr *ff_parse_expr(const char *s, const char * const *const_name, 65 double (* const *func1)(void *, double), const char * const *func1_name, 66 double (* const *func2)(void *, double, double), const char * const *func2_name, 67 const char **error); 68 69/** 70 * Evaluates a previously parsed expression. 71 * 72 * @param const_value a zero terminated array of values for the identifers from ff_parse const_name 73 * @param opaque a pointer which will be passed to all functions from func1 and func2 74 * @return the value of the expression 75 */ 76double ff_eval_expr(AVExpr * e, const double *const_value, void *opaque); 77 78/** 79 * Frees a parsed expression previously created with ff_parse(). 80 */ 81void ff_free_expr(AVExpr *e); 82 83/** 84 * Parses the string in numstr and returns its value as a double. If 85 * the string is empty, contains only whitespaces, or does not contain 86 * an initial substring that has the expected syntax for a 87 * floating-point number, no conversion is performed. In this case, 88 * returns a value of zero and the value returned in tail is the value 89 * of numstr. 90 * 91 * @param numstr a string representing a number, may contain one of 92 * the International System number postfixes, for example 'K', 'M', 93 * 'G'. If 'i' is appended after the postfix, powers of 2 are used 94 * instead of powers of 10. The 'B' postfix multiplies the value for 95 * 8, and can be appended after another postfix or used alone. This 96 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix. 97 * @param tail if non-NULL puts here the pointer to the char next 98 * after the last parsed character 99 */ 100double av_strtod(const char *numstr, char **tail); 101 102#endif /* AVCODEC_EVAL_H */ 103