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2134
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1 /*
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2 * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
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3 *
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4 * This file is part of FFmpeg.
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5 *
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6 * FFmpeg is free software; you can redistribute it and/or
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7 * modify it under the terms of the GNU Lesser General Public
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8 * License as published by the Free Software Foundation; either
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9 * version 2.1 of the License, or (at your option) any later version.
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10 *
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11 * FFmpeg is distributed in the hope that it will be useful,
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12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 * Lesser General Public License for more details.
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15 *
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16 * You should have received a copy of the GNU Lesser General Public
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17 * License along with FFmpeg; if not, write to the Free Software
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18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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19 */
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20
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21 /**
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22 * @file
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23 * simple arithmetic expression evaluator
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24 */
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25
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26 #ifndef AVUTIL_EVAL_H
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27 #define AVUTIL_EVAL_H
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28
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29 #include "avutil.h"
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30
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31 typedef struct AVExpr AVExpr;
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32
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33 /**
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34 * Parse and evaluate an expression.
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35 * Note, this is significantly slower than av_expr_eval().
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36 *
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37 * @param res a pointer to a double where is put the result value of
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38 * the expression, or NAN in case of error
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39 * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
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40 * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
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41 * @param const_values a zero terminated array of values for the identifiers from const_names
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42 * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
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43 * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
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44 * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
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45 * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
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46 * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
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47 * @param log_ctx parent logging context
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48 * @return 0 in case of success, a negative value corresponding to an
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49 * AVERROR code otherwise
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50 */
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51 int av_expr_parse_and_eval(double *res, const char *s,
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52 const char * const *const_names, const double *const_values,
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53 const char * const *func1_names, double (* const *funcs1)(void *, double),
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54 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
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55 void *opaque, int log_offset, void *log_ctx);
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56
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57 /**
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58 * Parse an expression.
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59 *
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60 * @param expr a pointer where is put an AVExpr containing the parsed
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61 * value in case of successful parsing, or NULL otherwise.
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62 * The pointed to AVExpr must be freed with av_expr_free() by the user
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63 * when it is not needed anymore.
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64 * @param s expression as a zero terminated string, for example "1+2^3+5*5+sin(2/3)"
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65 * @param const_names NULL terminated array of zero terminated strings of constant identifiers, for example {"PI", "E", 0}
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66 * @param func1_names NULL terminated array of zero terminated strings of funcs1 identifiers
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67 * @param funcs1 NULL terminated array of function pointers for functions which take 1 argument
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68 * @param func2_names NULL terminated array of zero terminated strings of funcs2 identifiers
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69 * @param funcs2 NULL terminated array of function pointers for functions which take 2 arguments
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70 * @param log_ctx parent logging context
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71 * @return 0 in case of success, a negative value corresponding to an
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72 * AVERROR code otherwise
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73 */
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74 int av_expr_parse(AVExpr **expr, const char *s,
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75 const char * const *const_names,
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76 const char * const *func1_names, double (* const *funcs1)(void *, double),
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77 const char * const *func2_names, double (* const *funcs2)(void *, double, double),
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78 int log_offset, void *log_ctx);
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79
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80 /**
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81 * Evaluate a previously parsed expression.
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82 *
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83 * @param const_values a zero terminated array of values for the identifiers from av_expr_parse() const_names
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84 * @param opaque a pointer which will be passed to all functions from funcs1 and funcs2
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85 * @return the value of the expression
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86 */
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87 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque);
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88
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89 /**
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90 * Free a parsed expression previously created with av_expr_parse().
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91 */
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92 void av_expr_free(AVExpr *e);
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93
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94 /**
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95 * Parse the string in numstr and return its value as a double. If
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96 * the string is empty, contains only whitespaces, or does not contain
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97 * an initial substring that has the expected syntax for a
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98 * floating-point number, no conversion is performed. In this case,
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99 * returns a value of zero and the value returned in tail is the value
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100 * of numstr.
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101 *
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102 * @param numstr a string representing a number, may contain one of
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103 * the International System number postfixes, for example 'K', 'M',
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104 * 'G'. If 'i' is appended after the postfix, powers of 2 are used
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105 * instead of powers of 10. The 'B' postfix multiplies the value for
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106 * 8, and can be appended after another postfix or used alone. This
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107 * allows using for example 'KB', 'MiB', 'G' and 'B' as postfix.
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108 * @param tail if non-NULL puts here the pointer to the char next
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109 * after the last parsed character
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110 */
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111 double av_strtod(const char *numstr, char **tail);
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112
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113 #endif /* AVUTIL_EVAL_H */
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