/*****************************************************************
 *
 *               The Compcert verified compiler
 *
 *           Xavier Leroy, INRIA Paris-Rocquencourt
 *
 * Copyright (c) 2013 Institut National de Recherche en Informatique et
 *  en Automatique.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of the <organization> 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 COPYRIGHT HOLDERS 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 <COPYRIGHT
 * HOLDER> 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.
 *
 **********************************************************************/

/* Helper functions for 64-bit integer arithmetic. Reference C implementation */

#include "i64.h"

/* Shift right unsigned */

unsigned long long i64_shr(unsigned long long x, int amount)
{
  unsigned xl = x, xh = x >> 32;
  amount = amount & 63;
  if (amount == 0) {
    return x;
  }
  else if (amount < 32) {
    unsigned rl = (xl >> amount) | (xh << (32 - amount));
    unsigned rh = xh >> amount;
    return rl | ((unsigned long long) rh << 32);
  } else {
    return (unsigned long long) (xh >> (amount - 32));
  }
}
