eval.c

/*
 * simple arithmetic expression evaluator
 *
 * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
 * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
 *
 * 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 eval.c
 * simple arithmetic expression evaluator.
 *
 * see http://joe.hotchkiss.com/programming/eval/eval.html
 */

#include "avcodec.h"
#include "mpegvideo.h"
#include "eval.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#ifndef NAN
  #define NAN 0.0/0.0
#endif

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

typedef struct Parser{
    int stack_index;
    char *s;
    double *const_value;
    const char **const_name;          // NULL terminated
    double (**func1)(void *, double a); // NULL terminated
    const char **func1_name;          // NULL terminated
    double (**func2)(void *, double a, double b); // NULL terminated
    char **func2_name;          // NULL terminated
    void *opaque;
    char **error;
#define VARS 10
    double var[VARS];
} Parser;

static int8_t si_prefixes['z' - 'E' + 1]={
    ['y'-'E']= -24,
    ['z'-'E']= -21,
    ['a'-'E']= -18,
    ['f'-'E']= -15,
    ['p'-'E']= -12,
    ['n'-'E']= - 9,