1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This software was developed by the Computer Systems Engineering group 6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 7 * contributed to Berkeley. 8 * 9 * %sccs.include.redist.c% 10 */ 11 12 #if defined(LIBC_SCCS) && !defined(lint) 13 static char sccsid[] = "@(#)subdi3.c 8.1 (Berkeley) 06/04/93"; 14 #endif /* LIBC_SCCS and not lint */ 15 16 #include "quad.h" 17 18 /* 19 * Subtract two quad values. This is trivial since a one-bit carry 20 * from a single u_long difference x-y occurs if and only if (x-y) > x. 21 */ 22 quad_t 23 __subdi3(a, b) 24 quad_t a, b; 25 { 26 union uu aa, bb, diff; 27 28 aa.q = a; 29 bb.q = b; 30 diff.ul[L] = aa.ul[L] - bb.ul[L]; 31 diff.ul[H] = aa.ul[H] - bb.ul[H] - (diff.ul[L] > aa.ul[L]); 32 return (diff.q); 33 } 34