Doxument ff_free_expr().
[libav.git] / libavcodec / eval.h
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1/*
2 * simple arithmetic expression evaluator
3 *
4 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
5 *
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6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
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9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
b78e7197 11 * version 2.1 of the License, or (at your option) any later version.
b2f86c17 12 *
b78e7197 13 * FFmpeg is distributed in the hope that it will be useful,
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14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
b78e7197 19 * License along with FFmpeg; if not, write to the Free Software
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20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23/**
bad5537e 24 * @file libavcodec/eval.h
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25 * eval header.
26 */
27
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28#ifndef AVCODEC_EVAL_H
29#define AVCODEC_EVAL_H
b2f86c17 30
073f6d5b 31typedef struct ff_expr_s AVExpr;
5fccafdb 32
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33/**
34 * Parses and evaluates an expression.
483b8b12 35 * Note, this is significantly slower than ff_parse_eval()
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36 * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"
37 * @param func1 NULL terminated array of function pointers for functions which take 1 argument
38 * @param func2 NULL terminated array of function pointers for functions which take 2 arguments
39 * @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
40 * @param func1_name NULL terminated array of zero terminated strings of func1 identifers
41 * @param func2_name NULL terminated array of zero terminated strings of func2 identifers
42 * @param error pointer to a char* which is set to an error message if something goes wrong
43 * @param const_value a zero terminated array of values for the identifers from const_name
44 * @param opaque a pointer which will be passed to all functions from func1 and func2
45 * @return the value of the expression
46 */
cac55c91 47double ff_eval2(const char *s, const double *const_value, const char * const *const_name,
b2f86c17 48 double (**func1)(void *, double), const char **func1_name,
cac55c91 49 double (**func2)(void *, double, double), const char **func2_name,
20e4beae 50 void *opaque, const char **error);
b2f86c17 51
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52/**
53 * Parses a expression.
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
f8fea468 61 * @return AVExpr which must be freed with ff_free_expr() by the user when it is not needed anymore
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62 * NULL if anything went wrong
63 */
073f6d5b 64AVExpr * ff_parse(const char *s, const char * const *const_name,
85b4eb08 65 double (**func1)(void *, double), const char **func1_name,
cac55c91 66 double (**func2)(void *, double, double), const char **func2_name,
20e4beae 67 const char **error);
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68/**
69 * Evaluates a previously parsed expression.
70 * @param const_value a zero terminated array of values for the identifers from ff_parse const_name
71 * @param opaque a pointer which will be passed to all functions from func1 and func2
72 * @return the value of the expression
73 */
073f6d5b 74double ff_parse_eval(AVExpr * e, const double *const_value, void *opaque);
f8fea468 75
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76/**
77 * Frees a parsed expression previously created with ff_parse().
78 */
f8fea468 79void ff_free_expr(AVExpr *e);
85b4eb08 80
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81/**
82 * Parses the string in numstr and returns its value as a double. If
83 * the string is empty, contains only whitespaces, or does not contain
84 * an initial substring that has the expected syntax for a
85 * floating-point number, no conversion is performed. In this case,
86 * returns a value of zero and the value returned in tail is the value
87 * of numstr.
88 *
89 * @param numstr a string representing a number, may contain one of
90 * the International System number postfixes, for example 'K', 'M',
91 * 'G'. If 'i' is appended after the postfix, powers of 2 are used
92 * instead of powers of 10. The 'B' postfix multiplies the value for
93 * 8, and can be appended after another postfix or used alone. This
94 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
95 * @param tail if non-NULL puts here the pointer to the char next
96 * after the last parsed character
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97 */
98double av_strtod(const char *numstr, char **tail);
99
98790382 100#endif /* AVCODEC_EVAL_H */