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comparison src/share/vm/runtime/atomic.cpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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children ba764ed4b6f2
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-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_atomic.cpp.incl"
27
28 jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
29 assert(sizeof(jbyte) == 1, "assumption.");
30 uintptr_t dest_addr = (uintptr_t)dest;
31 uintptr_t offset = dest_addr % sizeof(jint);
32 volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
33 jint cur = *dest_int;
34 jbyte* cur_as_bytes = (jbyte*)(&cur);
35 jint new_val = cur;
36 jbyte* new_val_as_bytes = (jbyte*)(&new_val);
37 new_val_as_bytes[offset] = exchange_value;
38 while (cur_as_bytes[offset] == compare_value) {
39 jint res = cmpxchg(new_val, dest_int, cur);
40 if (res == cur) break;
41 cur = res;
42 new_val = cur;
43 new_val_as_bytes[offset] = exchange_value;
44 }
45 return cur_as_bytes[offset];
46 }