ashrdi3.c

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    1 /*      $NetBSD: ashrdi3.c,v 1.9 2003/08/07 16:32:06 agc Exp $  */
    2 
    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 #if defined(LIBC_SCCS) && !defined(lint)
   38 #if 0
   39 static char sccsid[] = "@(#)ashrdi3.c   8.1 (Berkeley) 6/4/93";
   40 #else
   41 __RCSID("$NetBSD: ashrdi3.c,v 1.9 2003/08/07 16:32:06 agc Exp $");
   42 #endif
   43 #endif /* LIBC_SCCS and not lint */
   44 
   45 #include "quad.h"
   46 
   47 /*
   48  * Shift a (signed) quad value right (arithmetic shift right).
   49  */
   50 quad_t
   51 __ashrdi3(a, shift)
   52         quad_t a;
   53         qshift_t shift;
   54 {
   55         union uu aa;
   56 
   57         if (shift == 0)
   58                 return(a);
   59         aa.q = a;
   60         if (shift >= INT_BITS) {
   61                 int s;
   62 
   63                 /*
   64                  * Smear bits rightward using the machine's right-shift
   65                  * method, whether that is sign extension or zero fill,
   66                  * to get the `sign word' s.  Note that shifting by
   67                  * INT_BITS is undefined, so we shift (INT_BITS-1),
   68                  * then 1 more, to get our answer.
   69                  */
   70                 /* LINTED inherits machine dependency */
   71                 s = (aa.sl[H] >> (INT_BITS - 1)) >> 1;
   72                 /* LINTED inherits machine dependency*/
   73                 aa.ul[L] = aa.sl[H] >> (shift - INT_BITS);
   74                 aa.ul[H] = s;
   75         } else {
   76                 aa.ul[L] = (aa.ul[L] >> shift) |
   77                     (aa.ul[H] << (INT_BITS - shift));
   78                 /* LINTED inherits machine dependency */
   79                 aa.sl[H] >>= shift;
   80         }
   81         return (aa.q);
   82 }

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FreeBSD/Linux Kernel Cross Reference sys/lib/libkern/ashrdi3.c

FreeBSD/Linux Kernel Cross Reference
sys/lib/libkern/ashrdi3.c