lib/ack/libp/rdr.c

   1 /* $Header$ */
   2 /*
   3  * (c) copyright 1983 by the Vrije Universiteit, Amsterdam, The Netherlands.
   4  *
   5  *          This product is part of the Amsterdam Compiler Kit.
   6  *
   7  * Permission to use, sell, duplicate or disclose this software must be
   8  * obtained in writing. Requests for such permissions may be sent to
   9  *
  10  *      Dr. Andrew S. Tanenbaum
  11  *      Wiskundig Seminarium
  12  *      Vrije Universiteit
  13  *      Postbox 7161
  14  *      1007 MC Amsterdam
  15  *      The Netherlands
  16  *
  17  */
  18
  19 /* Author: J.W. Stevenson */
  20
  21 #include        <pc_file.h>
  22
  23 #define BIG     1e17
  24
  25 extern          _rf();
  26 extern          _incpt();
  27 extern          _skipsp();
  28 extern int      _getsig();
  29 extern int      _getint();
  30 extern int      _fstdig();
  31 extern int      _nxtdig();
  32
  33 static double           r;
  34 static int              pow10;
  35
  36 static dig(ch) int ch; {
  37
  38         if (r>BIG)
  39                 pow10++;
  40         else
  41                 r = r*10.0 + ch;
  42 }
  43
  44 double _rdr(f) struct file *f; {
  45         int i; double e; int is_signed,ch;
  46
  47         r = 0;
  48         pow10 = 0;
  49         _rf(f);
  50         _skipsp(f);
  51         is_signed = _getsig(f);
  52         ch = _fstdig(f);
  53         do
  54                 dig(ch);
  55         while ((ch = _nxtdig(f)) >= 0);
  56         if (*f->ptr == '.') {
  57                 _incpt(f);
  58                 ch = _fstdig(f);
  59                 do {
  60                         dig(ch);
  61                         pow10--;
  62                 } while ((ch = _nxtdig(f)) >= 0);
  63         }
  64         if ((*f->ptr == 'e') || (*f->ptr == 'E')) {
  65                 _incpt(f);
  66                 pow10 += _getint(f);
  67         }
  68         if ((i = pow10) < 0)
  69                 i = -i;
  70         e = 1.0;
  71         while (--i >= 0)
  72                 e *= 10.0;
  73         if (pow10<0)
  74                 r /= e;
  75         else
  76                 r *= e;
  77         return(is_signed? -r : r);
  78 }