/*-
 * 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.
 */

/* 
 * The code has been taken from FreeBSD (sys/libkern/ucmpdi2.c) and is therefore 
 * BSD-licensed. Unnecessary functions have been removed and all typedefs required 
 * have been added.
 */

#include <metalsvm/stddef.h>

#define CHAR_BIT	8

#if BYTE_ORDER == LITTLE_ENDIAN
#define _QUAD_HIGHWORD	1
#define _QUAD_LOWWORD	0
#else
#define _QUAD_HIGHWORD	0
#define _QUAD_LOWWORD	1
#endif

/*
 * Define high and low longwords.
 */
#define H		_QUAD_HIGHWORD
#define L		_QUAD_LOWWORD

/*
 * Total number of bits in a quad_t and in the pieces that make it up.
 * These are used for shifting, and also below for halfword extraction
 * and assembly.
 */
#define QUAD_BITS	(sizeof(quad_t) * CHAR_BIT)
#define LONG_BITS	(sizeof(long) * CHAR_BIT)
#define HALF_BITS	(sizeof(long) * CHAR_BIT / 2)

typedef int64_t quad_t;
typedef uint32_t qshift_t;

/*
 * Depending on the desired operation, we view a `long long' (aka quad_t) in
 * one or more of the following formats.
 */
union uu {
	quad_t		q;		/* as a (signed) quad */
	quad_t		uq;		/* as an unsigned quad */
	int32_t		sl[2];		/* as two signed longs */
	uint32_t	ul[2];		/* as two unsigned longs */
};

/*
 * Shift an (unsigned) quad value right (logical shift right).
 */
quad_t
__lshrdi3(a, shift)
	quad_t a;
	qshift_t shift;
{
	union uu aa;

	aa.q = a;
	if (shift >= LONG_BITS) {
		aa.ul[L] = shift >= QUAD_BITS ? 0 :
		    aa.ul[H] >> (shift - LONG_BITS);
		aa.ul[H] = 0;
	} else if (shift > 0) {
		aa.ul[L] = (aa.ul[L] >> shift) |
		    (aa.ul[H] << (LONG_BITS - shift));
		aa.ul[H] >>= shift;
	}
	return (aa.q);
}