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 * 3. 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 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include <libkern/quad.h> 40 41 /* 42 * Shift a (signed) quad value right (arithmetic shift right). 43 */ 44 quad_t 45 __ashrdi3(quad_t a, qshift_t shift) 46 { 47 union uu aa; 48 49 aa.q = a; 50 if (shift >= LONG_BITS) { 51 long s; 52 53 /* 54 * Smear bits rightward using the machine's right-shift 55 * method, whether that is sign extension or zero fill, 56 * to get the `sign word' s. Note that shifting by 57 * LONG_BITS is undefined, so we shift (LONG_BITS-1), 58 * then 1 more, to get our answer. 59 */ 60 s = (aa.sl[H] >> (LONG_BITS - 1)) >> 1; 61 aa.ul[L] = shift >= QUAD_BITS ? s : 62 aa.sl[H] >> (shift - LONG_BITS); 63 aa.ul[H] = s; 64 } else if (shift > 0) { 65 aa.ul[L] = (aa.ul[L] >> shift) | 66 (aa.ul[H] << (LONG_BITS - shift)); 67 aa.sl[H] >>= shift; 68 } 69 return (aa.q); 70 } 71