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atomic_dec_64_cas.c revision 1.1 
      1 /*	$NetBSD: atomic_dec_64_cas.c,v 1.1 2007/11/29 15:27:57 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2007 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Jason R. Thorpe.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include "atomic_op_namespace.h"
     40 
     41 #include <sys/atomic.h>
     42 
     43 #ifdef __HAVE_ATOMIC64_OPS
     44 
     45 void
     46 atomic_dec_64(volatile uint64_t *addr)
     47 {
     48 	uint64_t old, new;
     49 
     50 	do {
     51 		old = *addr;
     52 		new = old - 1;
     53 	} while (atomic_cas_64(addr, old, new) != old);
     54 }
     55 
     56 #undef atomic_dec_64
     57 atomic_op_alias(atomic_dec_64,_atomic_dec_64)
     58 
     59 #if defined(_LP64)
     60 #undef atomic_dec_long
     61 atomic_op_alias(atomic_dec_long,_atomic_dec_64)
     62 __strong_alias(_atomic_dec_long,_atomic_dec_64)
     63 
     64 #undef atomic_dec_ptr
     65 atomic_op_alias(atomic_dec_ptr,_atomic_dec_64)
     66 __strong_alias(_atomic_dec_ptr,_atomic_dec_64)
     67 #endif /* _LP64 */
     68 
     69 #endif
     70