source: trunk/minix/lib/float/adder.c@ 11

/*
  (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
  See the copyright notice in the ACK home directory, in the file "Copyright".
*/

/* $Header: /cvsup/minix/src/lib/float/adder.c,v 1.1.1.1 2005/04/21 14:56:10 beng Exp $ */

/*
 *      these are the routines the routines to do 32 and  64-bit addition
 */

# ifdef EXT_DEBUG
# include <stdio.h>
# endif

# include "FP_types.h"
# define        UNKNOWN -1
# define        TRUE     1
# define        FALSE    0
# define        MAXBIT  0x80000000L

        /*
         *      add 64 bits
         */
int
b64_add(e1,e2)
                /*
                 * pointers to 64 bit 'registers'
                 */
register        B64     *e1,*e2;
{
                register        int     overflow;
                                int     carry;

                        /* add higher pair of 32 bits */
        overflow = ((unsigned long) 0xFFFFFFFF - e1->h_32 < e2->h_32);
        e1->h_32 += e2->h_32;

                        /* add lower pair of 32 bits */
        carry = ((unsigned long) 0xFFFFFFFF - e1->l_32 < e2->l_32);
        e1->l_32 += e2->l_32;
# ifdef EXT_DEBUG
        printf("\t\t\t\t\tb64_add: overflow (%d); internal carry(%d)\n",
                                        overflow,carry);
        fflush(stdout);
# endif
        if ((carry) && (++e1->h_32 == 0))
                return(TRUE);           /* had a 64 bit overflow */
        return(overflow);               /* return status from higher add */
}