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 /*

  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "runtime/atomic.hpp"

 #ifdef TARGET_OS_FAMILY_linux

 # include "os_linux.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_solaris

 # include "os_solaris.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_windows

 # include "os_windows.inline.hpp"

 #endif

 #ifdef TARGET_OS_FAMILY_bsd

 # include "os_bsd.inline.hpp"

 #endif

 #include "runtime/atomic.inline.hpp"

 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];

 }

 unsigned Atomic::xchg(unsigned int exchange_value, volatile unsigned int* dest) {

   assert(sizeof(unsigned int) == sizeof(jint), "more work to do");

   return (unsigned int)Atomic::xchg((jint)exchange_value, (volatile jint*)dest);

 }

 unsigned Atomic::cmpxchg(unsigned int exchange_value,

                          volatile unsigned int* dest, unsigned int compare_value) {

   assert(sizeof(unsigned int) == sizeof(jint), "more work to do");

   return (unsigned int)Atomic::cmpxchg((jint)exchange_value, (volatile jint*)dest,

                                        (jint)compare_value);

 }

 jlong Atomic::add(jlong    add_value, volatile jlong*    dest) {

   jlong old = load(dest);

   jlong new_value = old + add_value;

   while (old != cmpxchg(new_value, dest, old)) {

     old = load(dest);

     new_value = old + add_value;

   }

   return old;

 }

 void Atomic::inc(volatile short* dest) {

   // Most platforms do not support atomic increment on a 2-byte value. However,

   // if the value occupies the most significant 16 bits of an aligned 32-bit

   // word, then we can do this with an atomic add of 0x10000 to the 32-bit word.

   //

   // The least significant parts of this 32-bit word will never be affected, even

   // in case of overflow/underflow.

   //

   // Use the ATOMIC_SHORT_PAIR macro to get the desired alignment.

 #ifdef VM_LITTLE_ENDIAN

   assert((intx(dest) & 0x03) == 0x02, "wrong alignment");

   (void)Atomic::add(0x10000, (volatile int*)(dest-1));

 #else

   assert((intx(dest) & 0x03) == 0x00, "wrong alignment");

   (void)Atomic::add(0x10000, (volatile int*)(dest));

 #endif

 }

 void Atomic::dec(volatile short* dest) {

 #ifdef VM_LITTLE_ENDIAN

   assert((intx(dest) & 0x03) == 0x02, "wrong alignment");

   (void)Atomic::add(-0x10000, (volatile int*)(dest-1));

 #else

   assert((intx(dest) & 0x03) == 0x00, "wrong alignment");

   (void)Atomic::add(-0x10000, (volatile int*)(dest));

 #endif

 }