ashrdi3.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1992, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 4. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#if defined(LIBC_SCCS) && !defined(lint)
37static char sccsid[] = "@(#)ashrdi3.c	8.1 (Berkeley) 6/4/93";
38#endif /* LIBC_SCCS and not lint */
39#include <sys/cdefs.h>
40__FBSDID("$FreeBSD: stable/11/lib/libc/quad/ashrdi3.c 330897 2018-03-14 03:19:51Z eadler $");
41
42#include "quad.h"
43
44/*
45 * Shift a (signed) quad value right (arithmetic shift right).
46 */
47quad_t
48__ashrdi3(a, shift)
49	quad_t a;
50	qshift_t shift;
51{
52	union uu aa;
53
54	aa.q = a;
55	if (shift >= LONG_BITS) {
56		long s;
57
58		/*
59		 * Smear bits rightward using the machine's right-shift
60		 * method, whether that is sign extension or zero fill,
61		 * to get the `sign word' s.  Note that shifting by
62		 * LONG_BITS is undefined, so we shift (LONG_BITS-1),
63		 * then 1 more, to get our answer.
64		 */
65		s = (aa.sl[H] >> (LONG_BITS - 1)) >> 1;
66		aa.ul[L] = shift >= QUAD_BITS ? s :
67		    aa.sl[H] >> (shift - LONG_BITS);
68		aa.ul[H] = s;
69	} else if (shift > 0) {
70		aa.ul[L] = (aa.ul[L] >> shift) |
71		    (aa.ul[H] << (LONG_BITS - shift));
72		aa.sl[H] >>= shift;
73	}
74	return (aa.q);
75}
76