mirror of
https://github.com/FFmpeg/FFmpeg.git
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103 lines
4.7 KiB
C
103 lines
4.7 KiB
C
/*
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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 libavcodec/eval.h
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* simple arithmetic expression evaluator
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*/
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#ifndef AVCODEC_EVAL_H
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#define AVCODEC_EVAL_H
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typedef struct AVExpr AVExpr;
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/**
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* Parses and evaluates an expression.
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* Note, this is significantly slower than ff_eval_expr().
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*
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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 func1 NULL terminated array of function pointers for functions which take 1 argument
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* @param func2 NULL terminated array of function pointers for functions which take 2 arguments
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* @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
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* @param func1_name NULL terminated array of zero terminated strings of func1 identifers
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* @param func2_name NULL terminated array of zero terminated strings of func2 identifers
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* @param error pointer to a char* which is set to an error message if something goes wrong
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* @param const_value a zero terminated array of values for the identifers from const_name
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* @param opaque a pointer which will be passed to all functions from func1 and func2
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* @return the value of the expression
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*/
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double ff_parse_and_eval_expr(const char *s, const double *const_value, const char * const *const_name,
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double (* const *func1)(void *, double), const char * const *func1_name,
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double (* const *func2)(void *, double, double), const char * const *func2_name,
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void *opaque, const char **error);
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/**
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* Parses an expression.
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*
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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 func1 NULL terminated array of function pointers for functions which take 1 argument
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* @param func2 NULL terminated array of function pointers for functions which take 2 arguments
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* @param const_name NULL terminated array of zero terminated strings of constant identifers for example {"PI", "E", 0}
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* @param func1_name NULL terminated array of zero terminated strings of func1 identifers
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* @param func2_name NULL terminated array of zero terminated strings of func2 identifers
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* @param error pointer to a char* which is set to an error message if something goes wrong
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* @return AVExpr which must be freed with ff_free_expr() by the user when it is not needed anymore
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* NULL if anything went wrong
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*/
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AVExpr *ff_parse_expr(const char *s, const char * const *const_name,
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double (* const *func1)(void *, double), const char * const *func1_name,
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double (* const *func2)(void *, double, double), const char * const *func2_name,
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const char **error);
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/**
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* Evaluates a previously parsed expression.
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*
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* @param const_value a zero terminated array of values for the identifers from ff_parse const_name
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* @param opaque a pointer which will be passed to all functions from func1 and func2
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* @return the value of the expression
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*/
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double ff_eval_expr(AVExpr * e, const double *const_value, void *opaque);
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/**
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* Frees a parsed expression previously created with ff_parse().
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*/
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void ff_free_expr(AVExpr *e);
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/**
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* Parses the string in numstr and returns 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 for
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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 /* AVCODEC_EVAL_H */
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