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diff --git a/media/ffvpx/libavutil/eval.h b/media/ffvpx/libavutil/eval.h
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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
+
+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_offset log level offset, can be used to silence error messages
+ * @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_offset log level offset, can be used to silence error messages
+ * @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 e the AVExpr to evaluate
+ * @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);
+
+/**
+ * Track the presence of variables and their number of occurrences in a parsed expression
+ *
+ * @param e the AVExpr to track variables in
+ * @param counter a zero-initialized array where the count of each variable will be stored
+ * @param size size of array
+ * @return 0 on success, a negative value indicates that no expression or array was passed
+ * or size was zero
+ */
+int av_expr_count_vars(AVExpr *e, unsigned *counter, int size);
+
+/**
+ * Track the presence of user provided functions and their number of occurrences
+ * in a parsed expression.
+ *
+ * @param e the AVExpr to track user provided functions in
+ * @param counter a zero-initialized array where the count of each function will be stored
+ *                if you passed 5 functions with 2 arguments to av_expr_parse()
+ *                then for arg=2 this will use up to 5 entries.
+ * @param size size of array
+ * @param arg number of arguments the counted functions have
+ * @return 0 on success, a negative value indicates that no expression or array was passed
+ * or size was zero
+ */
+int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg);
+
+/**
+ * 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 */