lib/float/cif8.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 FLOAT (CIF n 8)
  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 cif8(ss,src)
  21 int     ss;     /* source size */
  22 long    src;    /* largest possible integer to convert */
  23 {
  24         EXTEND  buf;
  25         DOUBLE  *result;        /* for return value */
  26         short   *ipt;
  27         long    i_src;
  28
  29         result = (DOUBLE *) ((void *) &ss);     /* always */
  30         zrf_ext(&buf);
  31         if (ss == sizeof(long)) {
  32                 buf.exp = 31;
  33                 i_src = src;
  34         }
  35         else    {
  36                 ipt = (short *) &src;
  37                 i_src = (long) *ipt;
  38                 buf.exp = 15;
  39         }
  40         if (i_src == 0) {
  41                 zrf8(result);
  42                 return;
  43         }
  44                         /* ESTABLISHED THAT src != 0    */
  45                         /* adjust exponent field        */
  46         buf.sign = (i_src < 0) ? 0x8000 : 0;
  47                         /* clear sign bit of integer    */
  48                         /* move to mantissa field       */
  49         buf.m1 = (i_src < 0) ? -i_src : i_src;
  50                         /* adjust mantissa field        */
  51         if (ss != sizeof(long))
  52                 buf.m1 <<= 16;
  53         nrm_ext(&buf);
  54         compact(&buf,&result->d[0],8);
  55 }