1 /* 2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "runtime/atomic.hpp" 27 #ifdef TARGET_OS_FAMILY_linux 28 # include "os_linux.inline.hpp" 29 #endif 30 #ifdef TARGET_OS_FAMILY_solaris 31 # include "os_solaris.inline.hpp" 32 #endif 33 #ifdef TARGET_OS_FAMILY_windows 34 # include "os_windows.inline.hpp" 35 #endif 36 #ifdef TARGET_OS_FAMILY_bsd 37 # include "os_bsd.inline.hpp" 38 #endif 39 40 #include "runtime/atomic.inline.hpp" 41 42 jbyte Atomic::cmpxchg(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) { 43 assert(sizeof(jbyte) == 1, "assumption."); 44 uintptr_t dest_addr = (uintptr_t)dest; 45 uintptr_t offset = dest_addr % sizeof(jint); 46 volatile jint* dest_int = (volatile jint*)(dest_addr - offset); 47 jint cur = *dest_int; 48 jbyte* cur_as_bytes = (jbyte*)(&cur); 49 jint new_val = cur; 50 jbyte* new_val_as_bytes = (jbyte*)(&new_val); 51 new_val_as_bytes[offset] = exchange_value; 52 while (cur_as_bytes[offset] == compare_value) { 53 jint res = cmpxchg(new_val, dest_int, cur); 54 if (res == cur) break; 55 cur = res; 56 new_val = cur; 57 new_val_as_bytes[offset] = exchange_value; 58 } 59 return cur_as_bytes[offset]; 60 } 61 62 unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) { 63 assert(sizeof(unsigned int) == sizeof(jint), "more work to do"); 64 return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest); 65 } 66 67 unsigned Atomic::cmpxchg(unsigned int exchange_value, 68 volatile unsigned int* dest, unsigned int compare_value) { 69 assert(sizeof(unsigned int) == sizeof(jint), "more work to do"); 70 return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest, 71 (jint)compare_value); 72 } 73 74 jlong Atomic::add(jlong add_value, volatile jlong* dest) { 75 jlong old = load(dest); 76 jlong new_value = old + add_value; 77 while (old != cmpxchg(new_value, dest, old)) { 78 old = load(dest); 79 new_value = old + add_value; 80 } 81 return old; 82 } 83 84 void Atomic::inc(volatile short* dest) { 85 // Most platforms do not support atomic increment on a 2-byte value. However, 86 // if the value occupies the most significant 16 bits of an aligned 32-bit 87 // word, then we can do this with an atomic add of 0x10000 to the 32-bit word. 88 // 89 // The least significant parts of this 32-bit word will never be affected, even 90 // in case of overflow/underflow. 91 // 92 // Use the ATOMIC_SHORT_PAIR macro to get the desired alignment. 93 #ifdef VM_LITTLE_ENDIAN 94 assert((intx(dest) & 0x03) == 0x02, "wrong alignment"); 95 (void)Atomic::add(0x10000, (volatile int*)(dest-1)); 96 #else 97 assert((intx(dest) & 0x03) == 0x00, "wrong alignment"); 98 (void)Atomic::add(0x10000, (volatile int*)(dest)); 99 #endif 100 } 101 102 void Atomic::dec(volatile short* dest) { 103 #ifdef VM_LITTLE_ENDIAN 104 assert((intx(dest) & 0x03) == 0x02, "wrong alignment"); 105 (void)Atomic::add(-0x10000, (volatile int*)(dest-1)); 106 #else 107 assert((intx(dest) & 0x03) == 0x00, "wrong alignment"); 108 (void)Atomic::add(-0x10000, (volatile int*)(dest)); 109 #endif 110 } 111