external/bsd/pcc/dist/pcc-libs/libpcc/ashrdi3.c

   1 /*      $Id: ashrdi3.c,v 1.1.1.2 2009/09/04 00:27:36 gmcgarry Exp $     */
   2 /*      $NetBSD: ashrdi3.c,v 1.1 2005/12/20 19:28:51 christos Exp $     */
   3
   4 /*-
   5  * Copyright (c) 1992, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This software was developed by the Computer Systems Engineering group
   9  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
  10  * contributed to Berkeley.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include "quad.h"
  38
  39 /*
  40  * Shift a (signed) quad value right (arithmetic shift right).
  41  */
  42 quad_t
  43 __ashrdi3(quad_t a, qshift_t shift)
  44 {
  45         union uu aa;
  46
  47         if (shift == 0)
  48                 return(a);
  49         aa.q = a;
  50         if (shift >= INT_BITS) {
  51                 int 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                  * INT_BITS is undefined, so we shift (INT_BITS-1),
  58                  * then 1 more, to get our answer.
  59                  */
  60                 /* LINTED inherits machine dependency */
  61                 s = (aa.sl[H] >> (INT_BITS - 1)) >> 1;
  62                 /* LINTED inherits machine dependency*/
  63                 aa.ul[L] = aa.sl[H] >> (shift - INT_BITS);
  64                 aa.ul[H] = s;
  65         } else {
  66                 aa.ul[L] = (aa.ul[L] >> shift) |
  67                     (aa.ul[H] << (INT_BITS - shift));
  68                 /* LINTED inherits machine dependency */
  69                 aa.sl[H] >>= shift;
  70         }
  71         return (aa.q);
  72 }