138 lines
6.2 KiB
C
138 lines
6.2 KiB
C
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/*
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* Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* simple arithmetic expression evaluator
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*/
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#ifndef AVUTIL_EVAL_H
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#define AVUTIL_EVAL_H
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#include "avutil.h"
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typedef struct AVExpr AVExpr;
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/**
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* Parse and evaluate an expression.
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* Note, this is significantly slower than av_expr_eval().
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*
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* @param res a pointer to a double where is put the result value of
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* the expression, or NAN in case of error
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* @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
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* @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
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* @param const_values a zero terminated array of values for the identifiers from const_names
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* @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
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* @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
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* @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
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* @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
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* @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
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* @param log_ctx parent logging context
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* @return >= 0 in case of success, a negative value corresponding to an
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* AVERROR code otherwise
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*/
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int av_expr_parse_and_eval(double *res, const char *s,
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const char * const *const_names, const double *const_values,
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const char * const *func1_names, double (* const *funcs1)(void *, double),
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const char * const *func2_names, double (* const *funcs2)(void *, double, double),
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void *opaque, int log_offset, void *log_ctx);
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/**
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* Parse an expression.
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*
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* @param expr a pointer where is put an AVExpr containing the parsed
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* value in case of successful parsing, or NULL otherwise.
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* The pointed to AVExpr must be freed with av_expr_free() by the user
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* when it is not needed anymore.
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* @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
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* @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
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* @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
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* @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
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* @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
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* @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
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* @param log_ctx parent logging context
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* @return >= 0 in case of success, a negative value corresponding to an
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* AVERROR code otherwise
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*/
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int av_expr_parse(AVExpr **expr, const char *s,
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const char * const *const_names,
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const char * const *func1_names, double (* const *funcs1)(void *, double),
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const char * const *func2_names, double (* const *funcs2)(void *, double, double),
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int log_offset, void *log_ctx);
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/**
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* Evaluate a previously parsed expression.
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*
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* @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names
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* @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
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* @return the value of the expression
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*/
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double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
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/**
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* Track the presence of variables and their number of occurrences in a parsed expression
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*
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* @param counter a zero-initialized array where the count of each variable will be stored
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* @param size size of array
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* @return 0 on success, a negative value indicates that no expression or array was passed
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* or size was zero
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*/
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int av_expr_count_vars(AVExpr *e, unsigned *counter, int size);
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/**
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* Track the presence of user provided functions and their number of occurrences
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* in a parsed expression.
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*
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* @param counter a zero-initialized array where the count of each function will be stored
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* if you passed 5 functions with 2 arguments to av_expr_parse()
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* then for arg=2 this will use upto 5 entries.
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* @param size size of array
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* @param arg number of arguments the counted functions have
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* @return 0 on success, a negative value indicates that no expression or array was passed
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* or size was zero
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*/
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int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg);
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/**
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* Free a parsed expression previously created with av_expr_parse().
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*/
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void av_expr_free(AVExpr *e);
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/**
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* Parse the string in numstr and return its value as a double. If
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* the string is empty, contains only whitespaces, or does not contain
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* an initial substring that has the expected syntax for a
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* floating-point number, no conversion is performed. In this case,
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* returns a value of zero and the value returned in tail is the value
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* of numstr.
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*
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* @param numstr a string representing a number, may contain one of
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* the International System number postfixes, for example 'K', 'M',
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* 'G'. If 'i' is appended after the postfix, powers of 2 are used
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* instead of powers of 10. The 'B' postfix multiplies the value by
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* 8, and can be appended after another postfix or used alone. This
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* allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
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* @param tail if non-NULL puts here the pointer to the char next
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* after the last parsed character
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*/
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double av_strtod(const char *numstr, char **tail);
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#endif /* AVUTIL_EVAL_H */
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