1/*	$OpenBSD: ashrdi3.c,v 1.7 2015/10/01 02:32:07 guenther Exp $ */
2/*-
3 * Copyright (c) 1992, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This software was developed by the Computer Systems Engineering group
7 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
8 * contributed to Berkeley.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#include "quad.h"
36
37/*
38 * Shift a (signed) quad value right (arithmetic shift right).
39 */
40quad_t
41__ashrdi3(quad_t a, qshift_t shift)
42{
43	union uu aa;
44
45	if (shift == 0)
46		return(a);
47	aa.q = a;
48	if (shift >= INT_BITS) {
49		int s;
50
51		/*
52		 * Smear bits rightward using the machine's right-shift
53		 * method, whether that is sign extension or zero fill,
54		 * to get the `sign word' s.  Note that shifting by
55		 * INT_BITS is undefined, so we shift (INT_BITS-1),
56		 * then 1 more, to get our answer.
57		 */
58		s = (aa.sl[H] >> (INT_BITS - 1)) >> 1;
59		aa.ul[L] = aa.sl[H] >> (shift - INT_BITS);
60		aa.ul[H] = s;
61	} else {
62		aa.ul[L] = (aa.ul[L] >> shift) |
63		    (aa.ul[H] << (INT_BITS - shift));
64		aa.sl[H] >>= shift;
65	}
66	return (aa.q);
67}
68