minix/lib/ack/fphook/adder.fc

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