1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This software was developed by the Computer Systems Engineering group 6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and 7 * contributed to Berkeley. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include <libkern/quad.h> 38 39 /* 40 * Shift a (signed) quad value right (arithmetic shift right). 41 */ 42 quad_t 43 __ashrdi3(a, shift) 44 quad_t a; 45 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