libavcodec/eval.h

   1 /*
   2  * simple arithmetic expression evaluator
   3  *
   4  * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  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
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 /**
  24  * @file libavcodec/eval.h
  25  * eval header.
  26  */
  27
  28 #ifndef AVCODEC_EVAL_H
  29 #define AVCODEC_EVAL_H
  30
  31 /**
  32  * Parses and evaluates an expression.
  33  * Note, this is significantly slower than ff_parse_eval()
  34  * @param s expression as a zero terminated string for example "1+2^3+5*5+sin(2/3)"
  35  * @param func1 NULL terminated array of function pointers for functions which take 1 argument
  36  * @param func2 NULL terminated array of function pointers for functions which take 2 arguments
  37  * @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
  38  * @param func1_name NULL terminated array of zero terminated strings of func1 identifers
  39  * @param func2_name NULL terminated array of zero terminated strings of func2 identifers
  40  * @param error pointer to a char* which is set to an error message if something goes wrong
  41  * @param const_value a zero terminated array of values for the identifers from const_name
  42  * @param opaque a pointer which will be passed to all functions from func1 and func2
  43  * @return the value of the expression
  44  */
  45 double ff_eval2(const char *s, const double *const_value, const char * const *const_name,
  46                double (**func1)(void *, double), const char **func1_name,
  47                double (**func2)(void *, double, double), const char **func2_name,
  48                void *opaque, const char **error);
  49
  50 typedef struct ff_expr_s AVEvalExpr;
  51
  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
  61  * @return AVEvalExpr which must be freed with ff_eval_free by the user when it is not needed anymore
  62  *         NULL if anything went wrong
  63  */
  64 AVEvalExpr * ff_parse(const char *s, const char * const *const_name,
  65                double (**func1)(void *, double), const char **func1_name,
  66                double (**func2)(void *, double, double), const char **func2_name,
  67                const char **error);
  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  */
  74 double ff_parse_eval(AVEvalExpr * e, const double *const_value, void *opaque);
  75 void ff_eval_free(AVEvalExpr * e);
  76
  77 /**
  78  * Parses the string in numstr and returns its value as a double. If
  79  * the string is empty, contains only whitespaces, or does not contain
  80  * an initial substring that has the expected syntax for a
  81  * floating-point number, no conversion is performed. In this case,
  82  * returns a value of zero and the value returned in tail is the value
  83  * of numstr.
  84  *
  85  * @param numstr a string representing a number, may contain one of
  86  * the International System number postfixes, for example 'K', 'M',
  87  * 'G'. If 'i' is appended after the postfix, powers of 2 are used
  88  * instead of powers of 10. The 'B' postfix multiplies the value for
  89  * 8, and can be appended after another postfix or used alone. This
  90  * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
  91  * @param tail if non-NULL puts here the pointer to the char next
  92  * after the last parsed character
  93  */
  94 double av_strtod(const char *numstr, char **tail);
  95
  96 #endif /* AVCODEC_EVAL_H */