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src/share/vm/runtime/atomic.cpp@9f4457a14b58 (annotated)

src/share/vm/runtime/atomic.cpp

Wed, 09 Apr 2008 15:10:22 -0700

author

rasbold

date

Wed, 09 Apr 2008 15:10:22 -0700

changeset 544

9f4457a14b58

parent 435

a61af66fc99e

child 548

ba764ed4b6f2

permissions

-rw-r--r--

Merge

duke@435	1	/*
duke@435	2	* Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	# include "incls/_precompiled.incl"
duke@435	26	# include "incls/_atomic.cpp.incl"
duke@435	27
duke@435	28	jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
duke@435	29	assert(sizeof(jbyte) == 1, "assumption.");
duke@435	30	uintptr_t dest_addr = (uintptr_t)dest;
duke@435	31	uintptr_t offset = dest_addr % sizeof(jint);
duke@435	32	volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
duke@435	33	jint cur = *dest_int;
duke@435	34	jbyte* cur_as_bytes = (jbyte*)(&cur);
duke@435	35	jint new_val = cur;
duke@435	36	jbyte* new_val_as_bytes = (jbyte*)(&new_val);
duke@435	37	new_val_as_bytes[offset] = exchange_value;
duke@435	38	while (cur_as_bytes[offset] == compare_value) {
duke@435	39	jint res = cmpxchg(new_val, dest_int, cur);
duke@435	40	if (res == cur) break;
duke@435	41	cur = res;
duke@435	42	new_val = cur;
duke@435	43	new_val_as_bytes[offset] = exchange_value;
duke@435	44	}
duke@435	45	return cur_as_bytes[offset];
duke@435	46	}