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 */
40 quad_t
__ashrdi3(quad_t a,qshift_t shift)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