/*

 * Copyright (c) 1999, 2013, 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

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 */

#ifndef SHARE_VM_RUNTIME_ATOMIC_HPP

#define SHARE_VM_RUNTIME_ATOMIC_HPP

#include "memory/allocation.hpp"

class Atomic : AllStatic {

 public:

  // Atomic operations on jlong types are not available on all 32-bit

  // platforms. If atomic ops on jlongs are defined here they must only

  // be used from code that verifies they are available at runtime and

  // can provide an alternative action if not - see supports_cx8() for

  // a means to test availability.

  // Atomically store to a location

  inline static void store    (jbyte    store_value, jbyte*    dest);

  inline static void store    (jshort   store_value, jshort*   dest);

  inline static void store    (jint     store_value, jint*     dest);

  // See comment above about using jlong atomics on 32-bit platforms

  inline static void store    (jlong    store_value, jlong*    dest);

  inline static void store_ptr(intptr_t store_value, intptr_t* dest);

  inline static void store_ptr(void*    store_value, void*     dest);

  inline static void store    (jbyte    store_value, volatile jbyte*    dest);

  inline static void store    (jshort   store_value, volatile jshort*   dest);

  inline static void store    (jint     store_value, volatile jint*     dest);

  // See comment above about using jlong atomics on 32-bit platforms

  inline static void store    (jlong    store_value, volatile jlong*    dest);

  inline static void store_ptr(intptr_t store_value, volatile intptr_t* dest);

  inline static void store_ptr(void*    store_value, volatile void*     dest);

  // See comment above about using jlong atomics on 32-bit platforms

  inline static jlong load(volatile jlong* src);

  // Atomically add to a location, return updated value

  inline static jint     add    (jint     add_value, volatile jint*     dest);

  inline static intptr_t add_ptr(intptr_t add_value, volatile intptr_t* dest);

  inline static void*    add_ptr(intptr_t add_value, volatile void*     dest);

  // See comment above about using jlong atomics on 32-bit platforms

         static jlong    add    (jlong    add_value, volatile jlong*    dest);

  // Atomically increment location

  inline static void inc    (volatile jint*     dest);

         static void inc    (volatile jshort*   dest);

  inline static void inc_ptr(volatile intptr_t* dest);

  inline static void inc_ptr(volatile void*     dest);

  // Atomically decrement a location

  inline static void dec    (volatile jint*     dest);

         static void dec    (volatile jshort*    dest);

  inline static void dec_ptr(volatile intptr_t* dest);

  inline static void dec_ptr(volatile void*     dest);

  // Performs atomic exchange of *dest with exchange_value.  Returns old prior value of *dest.

  inline static jint         xchg(jint         exchange_value, volatile jint*         dest);

         static unsigned int xchg(unsigned int exchange_value, volatile unsigned int* dest);

  inline static intptr_t xchg_ptr(intptr_t exchange_value, volatile intptr_t* dest);

  inline static void*    xchg_ptr(void*    exchange_value, volatile void*   dest);

  // Performs atomic compare of *dest and compare_value, and exchanges *dest with exchange_value

  // if the comparison succeeded.  Returns prior value of *dest.  Guarantees a two-way memory

  // barrier across the cmpxchg.  I.e., it's really a 'fence_cmpxchg_acquire'.

         static jbyte    cmpxchg    (jbyte    exchange_value, volatile jbyte*    dest, jbyte    compare_value);

  inline static jint     cmpxchg    (jint     exchange_value, volatile jint*     dest, jint     compare_value);

  // See comment above about using jlong atomics on 32-bit platforms

  inline static jlong    cmpxchg    (jlong    exchange_value, volatile jlong*    dest, jlong    compare_value);

         static unsigned int cmpxchg(unsigned int exchange_value,

                                     volatile unsigned int* dest,

                                     unsigned int compare_value);

  inline static intptr_t cmpxchg_ptr(intptr_t exchange_value, volatile intptr_t* dest, intptr_t compare_value);

  inline static void*    cmpxchg_ptr(void*    exchange_value, volatile void*     dest, void*    compare_value);

};

// To use Atomic::inc(jshort* dest) and Atomic::dec(jshort* dest), the address must be specially

// aligned, such that (*dest) occupies the upper 16 bits of an aligned 32-bit word. The best way to

// achieve is to place your short value next to another short value, which doesn't need atomic ops.

//

// Example

//  ATOMIC_SHORT_PAIR(

//    volatile short _refcount,  // needs atomic operation

//    unsigned short _length     // number of UTF8 characters in the symbol (does not need atomic op)

//  );

#ifdef VM_LITTLE_ENDIAN

#define ATOMIC_SHORT_PAIR(atomic_decl, non_atomic_decl) \

    non_atomic_decl; \

    atomic_decl

#else

#define ATOMIC_SHORT_PAIR(atomic_decl, non_atomic_decl) \

    atomic_decl ; \

    non_atomic_decl

#endif

#endif // SHARE_VM_RUNTIME_ATOMIC_HPP