aac5773f
 hucm
功能基本完成，接口待打磨
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/*
* Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* simple arithmetic expression evaluator
*/
#ifndef AVUTIL_EVAL_H
#define AVUTIL_EVAL_H
#include "avutil.h"
typedef struct AVExpr AVExpr;
/**
* Parse and evaluate an expression.
* Note, this is significantly slower than av_expr_eval().
*
* @param res a pointer to a double where is put the result value of
* the expression, or NAN in case of error
* @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
* @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
* @param const_values a zero terminated array of values for the identifiers from const_names
* @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
* @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
* @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
* @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
* @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
* @param log_ctx parent logging context
* @return >= 0 in case of success, a negative value corresponding to an
* AVERROR code otherwise
*/
int av_expr_parse_and_eval(double *res, const char *s,
const char * const *const_names, const double *const_values,
const char * const *func1_names, double (* const *funcs1)(void *, double),
const char * const *func2_names, double (* const *funcs2)(void *, double, double),
void *opaque, int log_offset, void *log_ctx);
/**
* Parse an expression.
*
* @param expr a pointer where is put an AVExpr containing the parsed
* value in case of successful parsing, or NULL otherwise.
* The pointed to AVExpr must be freed with av_expr_free() by the user
* when it is not needed anymore.
* @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
* @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
* @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
* @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
* @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
* @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
* @param log_ctx parent logging context
* @return >= 0 in case of success, a negative value corresponding to an
* AVERROR code otherwise
*/
int av_expr_parse(AVExpr **expr, const char *s,
const char * const *const_names,
const char * const *func1_names, double (* const *funcs1)(void *, double),
const char * const *func2_names, double (* const *funcs2)(void *, double, double),
int log_offset, void *log_ctx);
/**
* Evaluate a previously parsed expression.
*
* @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names
* @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
* @return the value of the expression
*/
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
/**
* Free a parsed expression previously created with av_expr_parse().
*/
void av_expr_free(AVExpr *e);
/**
* Parse the string in numstr and return its value as a double. If
* the string is empty, contains only whitespaces, or does not contain
* an initial substring that has the expected syntax for a
* floating-point number, no conversion is performed. In this case,
* returns a value of zero and the value returned in tail is the value
* of numstr.
*
* @param numstr a string representing a number, may contain one of
* the International System number postfixes, for example 'K', 'M',
* 'G'. If 'i' is appended after the postfix, powers of 2 are used
* instead of powers of 10. The 'B' postfix multiplies the value by
* 8, and can be appended after another postfix or used alone. This
* allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
* @param tail if non-NULL puts here the pointer to the char next
* after the last parsed character
*/
double av_strtod(const char *numstr, char **tail);
#endif /* AVUTIL_EVAL_H */
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