1998-06-09 08:21:55 +00:00
|
|
|
/*
|
|
|
|
|
* Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
|
|
|
|
|
* All rights reserved.
|
|
|
|
|
* copyright Douglas Santry 1996
|
|
|
|
|
*
|
|
|
|
|
* Redistribution and use in source and binary forms, with or without
|
|
|
|
|
* modification, are permitted provided that the above copyright is retained
|
|
|
|
|
* in the source form.
|
|
|
|
|
*
|
|
|
|
|
* THIS SOFTWARE IS PROVIDED BY Douglas Santry 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 Douglas Santry 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.
|
|
|
|
|
*
|
1999-08-28 00:22:10 +00:00
|
|
|
* $FreeBSD$
|
1998-06-09 08:21:55 +00:00
|
|
|
*
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#include "SYS.h"
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Atomicly lock a location with an identifier provided the location
|
|
|
|
|
* is not currently locked.
|
|
|
|
|
*
|
|
|
|
|
* long _atomic_lock(long *);
|
|
|
|
|
* v0 will contain the return value (zero if lock obtained).
|
|
|
|
|
*/
|
|
|
|
|
LEAF(_atomic_lock,0)
|
|
|
|
|
LDGP(pv)
|
|
|
|
|
|
1998-09-16 09:27:05 +00:00
|
|
|
0: ldq_l v0, 0(a0) /* read existing lock value */
|
|
|
|
|
mov 1, t0 /* locked value to store */
|
|
|
|
|
stq_c t0, 0(a0) /* attempt to store, status in t0 */
|
|
|
|
|
beq t0, 1f /* branch foward to optimise prediction */
|
|
|
|
|
mb /* sync with other processors */
|
|
|
|
|
RET /* return with v0==0 if lock obtained */
|
|
|
|
|
1: br 0b /* loop to try again */
|
1998-06-09 08:21:55 +00:00
|
|
|
END(_atomic_lock)
|
