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69 lines
2.5 KiB
C
69 lines
2.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This software was developed by the Computer Systems Engineering group
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* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
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* contributed to Berkeley.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <libkern/quad.h>
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/*
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* Shift a (signed) quad value right (arithmetic shift right).
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*/
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quad_t
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__ashrdi3(quad_t a, qshift_t shift)
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{
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union uu aa;
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aa.q = a;
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if (shift >= LONG_BITS) {
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long s;
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/*
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* Smear bits rightward using the machine's right-shift
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* method, whether that is sign extension or zero fill,
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* to get the `sign word' s. Note that shifting by
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* LONG_BITS is undefined, so we shift (LONG_BITS-1),
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* then 1 more, to get our answer.
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*/
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s = (aa.sl[H] >> (LONG_BITS - 1)) >> 1;
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aa.ul[L] = shift >= QUAD_BITS ? s :
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aa.sl[H] >> (shift - LONG_BITS);
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aa.ul[H] = s;
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} else if (shift > 0) {
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aa.ul[L] = (aa.ul[L] >> shift) |
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(aa.ul[H] << (LONG_BITS - shift));
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aa.sl[H] >>= shift;
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}
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return (aa.q);
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}
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