lib/float/cif4.c

   1 /*
   2   (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
   3   See the copyright notice in the ACK home directory, in the file "Copyright".
   4 */
   5
   6 /* $Header$ */
   7
   8 /*
   9         CONVERT INTEGER TO SINGLE (CIF n 4)
  10
  11         THIS ROUTINE WORKS BY FILLING AN EXTENDED
  12         WITH THE INTEGER VALUE IN EXTENDED FORMAT
  13         AND USES COMPACT() TO PUT IT INTO THE PROPER
  14         FLOATING POINT PRECISION.
  15 */
  16
  17 #include "FP_types.h"
  18
  19 void
  20 cif4(ss,src)
  21 int     ss;     /* source size */
  22 long    src;    /* largest possible integer to convert */
  23 {
  24         EXTEND  buf;
  25         short   *ipt;
  26         long    i_src;
  27         SINGLE  *result;
  28
  29         zrf_ext(&buf);
  30         if (ss == sizeof(long)) {
  31                 buf.exp = 31;
  32                 i_src = src;
  33                 result = (SINGLE *) &src;
  34         }
  35         else    {
  36                 ipt = (short *) &src;
  37                 i_src = (long) *ipt;
  38                 buf.exp = 15;
  39                 result = (SINGLE *) &ss;
  40         }
  41         if (i_src == 0) {
  42                 *result = (SINGLE) 0L;
  43                 return;
  44         }
  45                         /* ESTABLISHED THAT src != 0    */
  46                         /* adjust exponent field        */
  47         buf.sign = (i_src < 0) ? 0x8000 : 0;
  48                         /* clear sign bit of integer    */
  49                         /* move to mantissa field       */
  50         buf.m1 = (i_src < 0) ? -i_src : i_src;
  51                         /* adjust mantissa field        */
  52         if (ss != sizeof(long))
  53                 buf.m1 <<= 16;
  54         nrm_ext(&buf);          /* adjust mantissa field        */
  55         compact(&buf, result,sizeof(SINGLE));   /* put on stack */
  56 }