media/ffvpx/libavutil/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 AVUTIL_EVAL_H
  27 #define AVUTIL_EVAL_H
  28
  29 typedef struct AVExpr AVExpr;
  30
  31 /**
  32  * Parse and evaluate an expression.
  33  * Note, this is significantly slower than av_expr_eval().
  34  *
  35  * @param res a pointer to a double where is put the result value of
  36  * the expression, or NAN in case of error
  37  * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
  38  * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
  39  * @param const_values a zero terminated array of values for the identifiers from const_names
  40  * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
  41  * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
  42  * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
  43  * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
  44  * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
  45  * @param log_offset log level offset, can be used to silence error messages
  46  * @param log_ctx parent logging context
  47  * @return >= 0 in case of success, a negative value corresponding to an
  48  * AVERROR code otherwise
  49  */
  50 int av_expr_parse_and_eval(double *res, const char *s,
  51                            const char * const *const_names, const double *const_values,
  52                            const char * const *func1_names, double (* const *funcs1)(void *, double),
  53                            const char * const *func2_names, double (* const *funcs2)(void *, double, double),
  54                            void *opaque, int log_offset, void *log_ctx);
  55
  56 /**
  57  * Parse an expression.
  58  *
  59  * @param expr a pointer where is put an AVExpr containing the parsed
  60  * value in case of successful parsing, or NULL otherwise.
  61  * The pointed to AVExpr must be freed with av_expr_free() by the user
  62  * when it is not needed anymore.
  63  * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
  64  * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
  65  * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
  66  * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
  67  * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
  68  * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
  69  * @param log_offset log level offset, can be used to silence error messages
  70  * @param log_ctx parent logging context
  71  * @return >= 0 in case of success, a negative value corresponding to an
  72  * AVERROR code otherwise
  73  */
  74 int av_expr_parse(AVExpr **expr, const char *s,
  75                   const char * const *const_names,
  76                   const char * const *func1_names, double (* const *funcs1)(void *, double),
  77                   const char * const *func2_names, double (* const *funcs2)(void *, double, double),
  78                   int log_offset, void *log_ctx);
  79
  80 /**
  81  * Evaluate a previously parsed expression.
  82  *
  83  * @param e the AVExpr to evaluate
  84  * @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names
  85  * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
  86  * @return the value of the expression
  87  */
  88 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
  89
  90 /**
  91  * Track the presence of variables and their number of occurrences in a parsed expression
  92  *
  93  * @param e the AVExpr to track variables in
  94  * @param counter a zero-initialized array where the count of each variable will be stored
  95  * @param size size of array
  96  * @return 0 on success, a negative value indicates that no expression or array was passed
  97  * or size was zero
  98  */
  99 int av_expr_count_vars(AVExpr *e, unsigned *counter, int size);
 100
 101 /**
 102  * Track the presence of user provided functions and their number of occurrences
 103  * in a parsed expression.
 104  *
 105  * @param e the AVExpr to track user provided functions in
 106  * @param counter a zero-initialized array where the count of each function will be stored
 107  *                if you passed 5 functions with 2 arguments to av_expr_parse()
 108  *                then for arg=2 this will use up to 5 entries.
 109  * @param size size of array
 110  * @param arg number of arguments the counted functions have
 111  * @return 0 on success, a negative value indicates that no expression or array was passed
 112  * or size was zero
 113  */
 114 int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg);
 115
 116 /**
 117  * Free a parsed expression previously created with av_expr_parse().
 118  */
 119 void av_expr_free(AVExpr *e);
 120
 121 /**
 122  * Parse the string in numstr and return its value as a double. If
 123  * the string is empty, contains only whitespaces, or does not contain
 124  * an initial substring that has the expected syntax for a
 125  * floating-point number, no conversion is performed. In this case,
 126  * returns a value of zero and the value returned in tail is the value
 127  * of numstr.
 128  *
 129  * @param numstr a string representing a number, may contain one of
 130  * the International System number postfixes, for example 'K', 'M',
 131  * 'G'. If 'i' is appended after the postfix, powers of 2 are used
 132  * instead of powers of 10. The 'B' postfix multiplies the value by
 133  * 8, and can be appended after another postfix or used alone. This
 134  * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
 135  * @param tail if non-NULL puts here the pointer to the char next
 136  * after the last parsed character
 137  */
 138 double av_strtod(const char *numstr, char **tail);
 139
 140 #endif /* AVUTIL_EVAL_H */