d0004b1a14b383738a56c68b1e77200f40ab033e
[libav.git] / libavcodec / eval.h
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
29 typedef 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 const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
37 * @param const_value a zero terminated array of values for the identifers from const_name
38 * @param func1_name NULL terminated array of zero terminated strings of func1 identifers
39 * @param func1 NULL terminated array of function pointers for functions which take 1 argument
40 * @param func2_name NULL terminated array of zero terminated strings of func2 identifers
41 * @param func2 NULL terminated array of function pointers for functions which take 2 arguments
42 * @param opaque a pointer which will be passed to all functions from func1 and func2
43 * @param log_ctx parent logging context
44 * @return the value of the expression
45 */
46 double ff_parse_and_eval_expr(const char *s,
47 const char * const *const_name, const double *const_value,
48 const char * const *func1_name, double (* const *func1)(void *, double),
49 const char * const *func2_name, double (* const *func2)(void *, double, double),
50 void *opaque, int log_offset, void *log_ctx);
51
52 /**
53 * Parses an expression.
54 *
55 * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"
56 * @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
57 * @param func1_name NULL terminated array of zero terminated strings of func1 identifers
58 * @param func1 NULL terminated array of function pointers for functions which take 1 argument
59 * @param func2_name NULL terminated array of zero terminated strings of func2 identifers
60 * @param func2 NULL terminated array of function pointers for functions which take 2 arguments
61 * @param log_ctx parent logging context
62 * @return AVExpr which must be freed with ff_free_expr() by the user when it is not needed anymore
63 * NULL if anything went wrong
64 */
65 AVExpr *ff_parse_expr(const char *s,
66 const char * const *const_name,
67 const char * const *func1_name, double (* const *func1)(void *, double),
68 const char * const *func2_name, double (* const *func2)(void *, double, double),
69 int log_offset, void *log_ctx);
70
71 /**
72 * Evaluates a previously parsed expression.
73 *
74 * @param const_value a zero terminated array of values for the identifers from ff_parse const_name
75 * @param opaque a pointer which will be passed to all functions from func1 and func2
76 * @return the value of the expression
77 */
78 double ff_eval_expr(AVExpr * e, const double *const_value, void *opaque);
79
80 /**
81 * Frees a parsed expression previously created with ff_parse_expr().
82 */
83 void ff_free_expr(AVExpr *e);
84
85 /**
86 * Parses the string in numstr and returns its value as a double. If
87 * the string is empty, contains only whitespaces, or does not contain
88 * an initial substring that has the expected syntax for a
89 * floating-point number, no conversion is performed. In this case,
90 * returns a value of zero and the value returned in tail is the value
91 * of numstr.
92 *
93 * @param numstr a string representing a number, may contain one of
94 * the International System number postfixes, for example 'K', 'M',
95 * 'G'. If 'i' is appended after the postfix, powers of 2 are used
96 * instead of powers of 10. The 'B' postfix multiplies the value for
97 * 8, and can be appended after another postfix or used alone. This
98 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
99 * @param tail if non-NULL puts here the pointer to the char next
100 * after the last parsed character
101 */
102 double av_strtod(const char *numstr, char **tail);
103
104 #endif /* AVCODEC_EVAL_H */