projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 9ac3792a AM |
1 | /*- |
| 2 | * Copyright (c) 1992 The Regents of the University of California. | |
| 3 | * 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. All advertising materials mentioning features or use of this software | |
| 18 | * must display the following acknowledgement: | |
| 19 | * This product includes software developed by the University of | |
| 20 | * California, Berkeley and its contributors. | |
| 21 | * 4. Neither the name of the University nor the names of its contributors | |
| 22 | * may be used to endorse or promote products derived from this software | |
| 23 | * without specific prior written permission. | |
| 24 | * | |
| 25 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
| 26 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 27 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 28 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
| 29 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 30 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 31 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 32 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 33 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 34 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 35 | * SUCH DAMAGE. | |
| 36 | */ | |
| 37 | ||
| 38 | #if defined(LIBC_SCCS) && !defined(lint) | |
| 39 | static char sccsid[] = "@(#)ashrdi3.c 5.7 (Berkeley) 6/25/92"; | |
| 40 | #endif /* LIBC_SCCS and not lint */ | |
| 41 | ||
| 42 | #include "quad.h" | |
| 43 | ||
| 44 | /* | |
| 45 | * Shift a (signed) quad value right (arithmetic shift right). | |
| 46 | */ | |
| 47 | quad_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 | } |