lib/float/fif4.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         MULTIPLY AND DISMEMBER PARTS (FIF 4)
  10 */
  11
  12 #include "FP_types.h"
  13 #include "FP_shift.h"
  14
  15 void
  16 fif4(p,x,y)
  17 SINGLE  x,y;
  18 struct fif4_returns *p;
  19 {
  20
  21         EXTEND  e1,e2;
  22
  23         extend(&y,&e1,sizeof(SINGLE));
  24         extend(&x,&e2,sizeof(SINGLE));
  25                 /* do a multiply */
  26         mul_ext(&e1,&e2);
  27         e2 = e1;
  28         compact(&e2,&y,sizeof(SINGLE));
  29         if (e1.exp < 0) {
  30                 p->ipart = 0;
  31                 p->fpart = y;
  32                 return;
  33         }
  34         if (e1.exp > 30 - SGL_M1LEFT) {
  35                 p->ipart = y;
  36                 p->fpart = 0;
  37                 return;
  38         }
  39         b64_sft(&e1.mantissa, 63 - e1.exp);
  40         b64_sft(&e1.mantissa, e1.exp - 63);     /* "loose" low order bits */
  41         compact(&e1,&(p->ipart),sizeof(SINGLE));
  42         extend(&(p->ipart), &e2, sizeof(SINGLE));
  43         extend(&y, &e1, sizeof(SINGLE));
  44         sub_ext(&e1, &e2);
  45         compact(&e1, &(p->fpart), sizeof(SINGLE));
  46 }