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      1 /*	$NetBSD: rump_atomic_cas_up.c,v 1.2 2010/11/23 12:51:10 pooka Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2010 Antti Kantee.  All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS
     16  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     17  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     18  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS
     19  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     20  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     21  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     22  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     23  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     24  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     25  * POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #include <sys/cdefs.h>
     29 __KERNEL_RCSID(0, "$NetBSD: rump_atomic_cas_up.c,v 1.2 2010/11/23 12:51:10 pooka Exp $");
     30 
     31 /*
     32  * Uniprocessor version of atomic CAS.  Since there is no preemption
     33  * in rump, this is a piece of cake.
     34  */
     35 
     36 #include <sys/types.h>
     37 
     38 uint32_t rump_cas_32_up(volatile uint32_t *ptr, uint32_t, uint32_t);
     39 
     40 uint32_t
     41 rump_cas_32_up(volatile uint32_t *ptr, uint32_t old, uint32_t new)
     42 {
     43 	uint32_t ret;
     44 
     45 	ret = *ptr;
     46 	if (__predict_true(ret == old)) {
     47 		*ptr = new;
     48 	}
     49 
     50 	return ret;
     51 }
     52 
     53 __strong_alias(atomic_cas_32,rump_cas_32_up)
     54 __strong_alias(_atomic_cas_32,rump_cas_32_up)
     55 __strong_alias(atomic_cas_uint,rump_cas_32_up)
     56 __strong_alias(_atomic_cas_uint,rump_cas_32_up)
     57 __strong_alias(atomic_cas_ulong,rump_cas_32_up)
     58 __strong_alias(_atomic_cas_ulong,rump_cas_32_up)
     59 __strong_alias(atomic_cas_ptr,rump_cas_32_up)
     60 __strong_alias(_atomic_cas_ptr,rump_cas_32_up)
     61 __strong_alias(atomic_cas_32_ni,rump_cas_32_up)
     62 __strong_alias(_atomic_cas_32_ni,rump_cas_32_up)
     63 __strong_alias(atomic_cas_uint_ni,rump_cas_32_up)
     64 __strong_alias(_atomic_cas_uint_ni,rump_cas_32_up)
     65 __strong_alias(atomic_cas_ulong_ni,rump_cas_32_up)
     66 __strong_alias(_atomic_cas_ulong_ni,rump_cas_32_up)
     67 __strong_alias(atomic_cas_ptr_ni,rump_cas_32_up)
     68 __strong_alias(_atomic_cas_ptr_ni,rump_cas_32_up)
     69