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RIOT/sys/quad_math/ashrdi3.c 2.74 KB
a752c7ab   elopes   add first test an...
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  /* $OpenBSD: ashrdi3.c,v 1.6 2005/08/08 08:05:35 espie Exp $ */
  /*-
   * 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.
   * 3. 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.
   */
  
  #include "quad.h"
  
  /*
   * Shift a (signed) quad value right (arithmetic shift right).
   */
  quad_t __ashrdi3(quad_t a, qshift_t shift)
  {
      union uu aa;
  
      if (shift == 0) {
          return a;
      }
  
      aa.q = a;
  
      if (shift >= INT_BITS) {
          /*
           * 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
           * INT_BITS is undefined, so we shift (INT_BITS-1),
           * then 1 more, to get our answer.
           */
          /* LINTED inherits machine dependency */
          int s = (aa.sl[H] >> (INT_BITS - 1)) >> 1;
          /* LINTED inherits machine dependency*/
          aa.ul[L] = aa.sl[H] >> (shift - INT_BITS);
          aa.ul[H] = s;
      }
      else {
          aa.ul[L] = (aa.ul[L] >> shift) | (aa.ul[H] << (INT_BITS - shift));
          /* LINTED inherits machine dependency */
          aa.sl[H] >>= shift;
      }
  
      return aa.q;
  }