xref: /csrg-svn/lib/libc/quad/adddi3.c (revision 61153)
153431Sbostic /*-
2*61153Sbostic  * Copyright (c) 1992, 1993
3*61153Sbostic  *	The Regents of the University of California.  All rights reserved.
453431Sbostic  *
553794Sbostic  * This software was developed by the Computer Systems Engineering group
653794Sbostic  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
753794Sbostic  * contributed to Berkeley.
853794Sbostic  *
953431Sbostic  * %sccs.include.redist.c%
1053431Sbostic  */
1153431Sbostic 
1253431Sbostic #if defined(LIBC_SCCS) && !defined(lint)
13*61153Sbostic static char sccsid[] = "@(#)adddi3.c	8.1 (Berkeley) 06/04/93";
1453431Sbostic #endif /* LIBC_SCCS and not lint */
1553431Sbostic 
1653794Sbostic #include "quad.h"
1753459Sbostic 
1853794Sbostic /*
1953794Sbostic  * Add two quads.  This is trivial since a one-bit carry from a single
2053794Sbostic  * u_long addition x+y occurs if and only if the sum x+y is less than
2153794Sbostic  * either x or y (the choice to compare with x or y is arbitrary).
2253794Sbostic  */
2354431Sbostic quad_t
__adddi3(a,b)2454431Sbostic __adddi3(a, b)
2554431Sbostic 	quad_t a, b;
2653431Sbostic {
2753794Sbostic 	union uu aa, bb, sum;
2853431Sbostic 
2953794Sbostic 	aa.q = a;
3053794Sbostic 	bb.q = b;
3153794Sbostic 	sum.ul[L] = aa.ul[L] + bb.ul[L];
3253794Sbostic 	sum.ul[H] = aa.ul[H] + bb.ul[H] + (sum.ul[L] < bb.ul[L]);
3353794Sbostic 	return (sum.q);
3453431Sbostic }
35