/* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */
#include <math.h>

#define unconst(__v, __t) __extension__ ({union { const __t __cp; __t __p; } __q; __q.__cp = __v; __q.__p;})

double strtod(const char *s, char **sret)
{
    long double r;		/* result */
    int e;			/* exponent */
    long double d;		/* scale */
    int sign;			/* +- 1.0 */
    int esign;
    int i;
    int flags=0;

    r = 0.0;
    sign = 1.0;
    e = 0;
    esign = 1;

    while ((*s == ' ') || (*s == '\t'))
        s++;
        
    if (*s == '+')
        s++;
    else if (*s == '-')
    {
        sign = -1;
        s++;
    }

    while ((*s >= '0') && (*s <= '9'))
    {
        flags |= 1;
        r *= 10.0;
        r += *s - '0';
        s++;
    }

    if (*s == '.')
    { 
        d = 0.1L;
        s++;
    
        while ((*s >= '0') && (*s <= '9'))
        {
            flags |= 2;
            r += d * (*s - '0');
            s++;
            d *= 0.1L;
        }
    }

    if (flags == 0)
    {
        if (sret)
        *sret = unconst(s, char *);
        return 0;
    }

    if ((*s == 'e') || (*s == 'E'))
    {
        s++;
        if (*s == '+')
            s++;
        else if (*s == '-')
        {
            s++;
            esign = -1;
        }
        
        if ((*s < '0') || (*s > '9'))
        {
            if (sret)
	            *sret = unconst(s, char *);
            return r;
        }

        while ((*s >= '0') && (*s <= '9'))
        {
            e *= 10;
            e += *s - '0';
            s++;
        }
    }
    if (esign < 0)
        for (i = 1; i <= e; i++)
            r *= 0.1L;
    else
        for (i = 1; i <= e; i++)
            r *= 10.0;

    if (sret)
        *sret = unconst(s, char *);
    return r * sign;
}