lib/float/cfu.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 FLOAT TO UNSIGNED (CFU m n)
  10
  11                 N.B. The caller must know what it is getting.
  12                      A LONG is always returned. If it is an
  13                      integer the high byte is cleared first.
  14 */
  15
  16 #include "FP_trap.h"
  17 #include "FP_types.h"
  18
  19 long
  20 cfu(ds,ss,src)
  21 int     ds;     /* destination size (2 or 4) */
  22 int     ss;     /* source size      (4 or 8) */
  23 DOUBLE  src;    /* assume worst case */
  24 {
  25         EXTEND  buf;
  26         long    new;
  27         short   newint, max_exp;
  28
  29         extend(&src.d[0],&buf,ss);      /* get extended format  */
  30         if (buf.exp < 0) {      /* no conversion needed */
  31                 src.d[ss == 8] = 0L;
  32                 return(0L);
  33         }
  34         max_exp = (ds << 3) - 1;
  35         if (buf.exp > max_exp) {
  36                 trap(EIOVFL);   /* integer overflow     */
  37                 buf.exp %= max_exp;
  38         }
  39         new = buf.m1 >> (31-buf.exp);
  40 done:
  41         src.d[ss == 8] = new;
  42         return(new);
  43 }