| /* |
| * Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| # include "incls/_precompiled.incl" |
| # include "incls/_atomic.cpp.incl" |
| |
| jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) { |
| assert(sizeof(jbyte) == 1, "assumption."); |
| uintptr_t dest_addr = (uintptr_t)dest; |
| uintptr_t offset = dest_addr % sizeof(jint); |
| volatile jint* dest_int = (volatile jint*)(dest_addr - offset); |
| jint cur = *dest_int; |
| jbyte* cur_as_bytes = (jbyte*)(&cur); |
| jint new_val = cur; |
| jbyte* new_val_as_bytes = (jbyte*)(&new_val); |
| new_val_as_bytes[offset] = exchange_value; |
| while (cur_as_bytes[offset] == compare_value) { |
| jint res = cmpxchg(new_val, dest_int, cur); |
| if (res == cur) break; |
| cur = res; |
| new_val = cur; |
| new_val_as_bytes[offset] = exchange_value; |
| } |
| return cur_as_bytes[offset]; |
| } |
