rdr.c

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/* $Header: /opt/proj/minix/cvsroot/src/lib/ack/libp/rdr.c,v 1.1 2005/10/10 15:27:47 beng Exp $ */
/*
 * (c) copyright 1983 by the Vrije Universiteit, Amsterdam, The Netherlands.
 *
 *          This product is part of the Amsterdam Compiler Kit.
 *
 * Permission to use, sell, duplicate or disclose this software must be
 * obtained in writing. Requests for such permissions may be sent to
 *
 *      Dr. Andrew S. Tanenbaum
 *      Wiskundig Seminarium
 *      Vrije Universiteit
 *      Postbox 7161
 *      1007 MC Amsterdam
 *      The Netherlands
 *
 */

/* Author: J.W. Stevenson */

#include        <pc_file.h>

#define BIG     1e17

extern          _rf();
extern          _incpt();
extern          _skipsp();
extern int      _getsig();
extern int      _getint();
extern int      _fstdig();
extern int      _nxtdig();

static double           r;
static int              pow10;

static dig(ch) int ch; {

        if (r>BIG)
                pow10++;
        else
                r = r*10.0 + ch;
}

double _rdr(f) struct file *f; {
        int i; double e; int is_signed,ch;

        r = 0;
        pow10 = 0;
        _rf(f);
        _skipsp(f);
        is_signed = _getsig(f);
        ch = _fstdig(f);
        do
                dig(ch);
        while ((ch = _nxtdig(f)) >= 0);
        if (*f->ptr == '.') {
                _incpt(f);
                ch = _fstdig(f);
                do {
                        dig(ch);
                        pow10--;
                } while ((ch = _nxtdig(f)) >= 0);
        }
        if ((*f->ptr == 'e') || (*f->ptr == 'E')) {
                _incpt(f);
                pow10 += _getint(f);
        }
        if ((i = pow10) < 0)
                i = -i;
        e = 1.0;
        while (--i >= 0)
                e *= 10.0;
        if (pow10<0)
                r /= e;
        else
                r *= e;
        return(is_signed? -r : r);
}

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