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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include "nge.h"
/*
* Atomically decrement a counter, but only if it will remain
* positive (>=0) afterwards.
*/
boolean_t
nge_atomic_decrease(uint64_t *count_p, uint64_t n)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *count_p;
newval = oldval - n;
if (oldval < n)
return (B_FALSE);
} while (atomic_cas_64(count_p, oldval, newval) != oldval);
return (B_TRUE);
}
/*
* Atomically increment a counter
*/
void
nge_atomic_increase(uint64_t *count_p, uint64_t n)
{
uint64_t oldval;
uint64_t newval;
/* ATOMICALLY */
do {
oldval = *count_p;
newval = oldval + n;
} while (atomic_cas_64(count_p, oldval, newval) != oldval);
}
/*
* Atomically shift a 32-bit word left, returning
* the value it had *before* the shift was applied
*/
uint32_t
nge_atomic_shl32(uint32_t *sp, uint_t count)
{
uint32_t oldval;
uint32_t newval;
/* ATOMICALLY */
do {
oldval = *sp;
newval = oldval << count;
} while (atomic_cas_32(sp, oldval, newval) != oldval);
return (oldval);
}
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