port/fp/ashrdi3.c

/*
 * Copyright (c) 1992, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "quadint.h"

#pragma weak __ashrdi3 = ___ashrdi3

/*
 * Shift a (signed) quad value right (arithmetic shift right).
 */
longlong_t
___ashrdi3(longlong_t a, qshift_t shift)
{
    union uu aa;

    aa.q = a;
    if (shift >= LONG_BITS) {
        long s;

        /*
         * Smear bits rightward using the machine's right-shift
         * method, whether that is sign extension or zero fill,
         * to get the `sign word' s.  Note that shifting by
         * LONG_BITS is undefined, so we shift (LONG_BITS-1),
         * then 1 more, to get our answer.
         */
        s = (aa.sl[H] >> (LONG_BITS - 1)) >> 1;
        aa.ul[L] = shift >= QUAD_BITS ? s :
            aa.sl[H] >> (shift - LONG_BITS);
        aa.ul[H] = s;
    } else if (shift > 0) {
        aa.ul[L] = (aa.ul[L] >> shift) |
            (aa.ul[H] << (LONG_BITS - shift));
        aa.sl[H] >>= shift;
    }
    return (aa.q);
}