lib/float/adder.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  *      these are the routines the routines to do 32 and  64-bit addition
  10  */
  11
  12 # ifdef EXT_DEBUG
  13 # include <stdio.h>
  14 # endif
  15
  16 # include "FP_types.h"
  17 # define        UNKNOWN -1
  18 # define        TRUE     1
  19 # define        FALSE    0
  20 # define        MAXBIT  0x80000000L
  21
  22         /*
  23          *      add 64 bits
  24          */
  25 int
  26 b64_add(e1,e2)
  27                 /*
  28                  * pointers to 64 bit 'registers'
  29                  */
  30 register        B64     *e1,*e2;
  31 {
  32                 register        int     overflow;
  33                                 int     carry;
  34
  35                         /* add higher pair of 32 bits */
  36         overflow = ((unsigned long) 0xFFFFFFFF - e1->h_32 < e2->h_32);
  37         e1->h_32 += e2->h_32;
  38
  39                         /* add lower pair of 32 bits */
  40         carry = ((unsigned long) 0xFFFFFFFF - e1->l_32 < e2->l_32);
  41         e1->l_32 += e2->l_32;
  42 # ifdef EXT_DEBUG
  43         printf("\t\t\t\t\tb64_add: overflow (%d); internal carry(%d)\n",
  44                                         overflow,carry);
  45         fflush(stdout);
  46 # endif
  47         if ((carry) && (++e1->h_32 == 0))
  48                 return(TRUE);           /* had a 64 bit overflow */
  49         return(overflow);               /* return status from higher add */
  50 }