usr/src/lib/libc/quad/adddi3.c

/*-
 * Copyright (c) 1992 The Regents of the University of California.
 * All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)adddi3.c    5.4 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include "quad.h"

/*
 * Add two quads.  This is trivial since a one-bit carry from a single
 * u_long addition x+y occurs if and only if the sum x+y is less than
 * either x or y (the choice to compare with x or y is arbitrary).
 */
quad
__adddi3(quad a, quad b)
{
        union uu aa, bb, sum;

        aa.q = a;
        bb.q = b;
        sum.ul[L] = aa.ul[L] + bb.ul[L];
        sum.ul[H] = aa.ul[H] + bb.ul[H] + (sum.ul[L] < bb.ul[L]);
        return (sum.q);
}