1 /* $OpenBSD: ashrdi3.c,v 1.2 1997/11/07 15:56:37 niklas Exp $ */ 2 /* $NetBSD: ashrdi3.c,v 1.5 1995/10/07 09:26:18 mycroft Exp $ */ 3 4 /*- 5 * Copyright (c) 1992, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * This software was developed by the Computer Systems Engineering group 9 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 10 * contributed to Berkeley. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 */ 40 41 #if defined(LIBC_SCCS) && !defined(lint) 42 #if 0 43 static char sccsid[] = "@(#)ashrdi3.c 8.1 (Berkeley) 6/4/93"; 44 #else 45 static char rcsid[] = "$OpenBSD: ashrdi3.c,v 1.2 1997/11/07 15:56:37 niklas Exp $"; 46 #endif 47 #endif /* LIBC_SCCS and not lint */ 48 49 #include "quad.h" 50 51 /* 52 * Shift a (signed) quad value right (arithmetic shift right). 53 */ 54 quad_t 55 __ashrdi3(a, shift) 56 quad_t a; 57 qshift_t shift; 58 { 59 union uu aa; 60 61 aa.q = a; 62 if (shift >= LONG_BITS) { 63 long s; 64 65 /* 66 * Smear bits rightward using the machine's right-shift 67 * method, whether that is sign extension or zero fill, 68 * to get the `sign word' s. Note that shifting by 69 * LONG_BITS is undefined, so we shift (LONG_BITS-1), 70 * then 1 more, to get our answer. 71 */ 72 s = (aa.sl[H] >> (LONG_BITS - 1)) >> 1; 73 aa.ul[L] = shift >= QUAD_BITS ? s : 74 aa.sl[H] >> (shift - LONG_BITS); 75 aa.ul[H] = s; 76 } else if (shift > 0) { 77 aa.ul[L] = (aa.ul[L] >> shift) | 78 (aa.ul[H] << (LONG_BITS - shift)); 79 aa.sl[H] >>= shift; 80 } 81 return (aa.q); 82 } 83