3314f1b0c5
The comment above the code mentions that it should work even on machines that shift in zeroes.
84 lines
3.0 KiB
C
84 lines
3.0 KiB
C
/* $NetBSD: ashrdi3.c,v 1.6 1999/05/03 15:37:48 christos 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. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 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.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
#if defined(LIBC_SCCS) && !defined(lint)
|
|
#if 0
|
|
static char sccsid[] = "@(#)ashrdi3.c 8.1 (Berkeley) 6/4/93";
|
|
#else
|
|
__RCSID("$NetBSD: ashrdi3.c,v 1.6 1999/05/03 15:37:48 christos Exp $");
|
|
#endif
|
|
#endif /* LIBC_SCCS and not lint */
|
|
|
|
#include "quad.h"
|
|
|
|
/*
|
|
* Shift a (signed) quad value right (arithmetic shift right).
|
|
*/
|
|
quad_t
|
|
__ashrdi3(a, shift)
|
|
quad_t a;
|
|
qshift_t shift;
|
|
{
|
|
union uu aa;
|
|
|
|
if (shift == 0)
|
|
return(a);
|
|
aa.q = a;
|
|
if (shift >= LONG_BITS) {
|
|
long s;
|
|
|
|
/*
|
|
* 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
|
|
* LONG_BITS is undefined, so we shift (LONG_BITS-1),
|
|
* then 1 more, to get our answer.
|
|
*/
|
|
s = ((u_long)aa.sl[H] >> (LONG_BITS - 1)) >> 1;
|
|
aa.ul[L] = (u_long)aa.sl[H] >> (shift - LONG_BITS);
|
|
aa.ul[H] = s;
|
|
} else {
|
|
aa.ul[L] = (aa.ul[L] >> shift) |
|
|
(aa.ul[H] << (LONG_BITS - shift));
|
|
aa.sl[H] = (u_long)aa.sl[H] >> shift;
|
|
}
|
|
return (aa.q);
|
|
}
|