/*

 * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.

 * Copyright 2007, 2008, 2011, 2015, Red Hat, Inc.

 * 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.

 *

 */

#ifndef OS_CPU_LINUX_ZERO_VM_ATOMIC_LINUX_ZERO_HPP

#define OS_CPU_LINUX_ZERO_VM_ATOMIC_LINUX_ZERO_HPP

#include "runtime/os.hpp"

// Implementation of class atomic

#ifdef M68K

/*

 * __m68k_cmpxchg

 *

 * Atomically store newval in *ptr if *ptr is equal to oldval for user space.

 * Returns newval on success and oldval if no exchange happened.

 * This implementation is processor specific and works on

 * 68020 68030 68040 and 68060.

 *

 * It will not work on ColdFire, 68000 and 68010 since they lack the CAS

 * instruction.

 * Using a kernelhelper would be better for arch complete implementation.

 *

 */

static inline int __m68k_cmpxchg(int oldval, int newval, volatile int *ptr) {

  int ret;

  __asm __volatile ("cas%.l %0,%2,%1"

                   : "=d" (ret), "+m" (*(ptr))

                   : "d" (newval), "0" (oldval));

  return ret;

}

/* Perform an atomic compare and swap: if the current value of `*PTR'

   is OLDVAL, then write NEWVAL into `*PTR'.  Return the contents of

   `*PTR' before the operation.*/

  for (;;) {

      int prev = *ptr;

      if (prev != oldval)

        return prev;

      if (__m68k_cmpxchg (prev, newval, ptr) == newval)

        // Success.

        return prev;

      // We failed even though prev == oldval.  Try again.

    }

}

/* Atomically add an int to memory.  */

static inline int m68k_add_and_fetch(volatile int *ptr, int add_value) {

  for (;;) {

      // Loop until success.

      int prev = *ptr;

      if (__m68k_cmpxchg (prev, prev + add_value, ptr) == prev + add_value)

        return prev + add_value;

    }

}

/* Atomically write VALUE into `*PTR' and returns the previous

   contents of `*PTR'.  */

static inline int m68k_lock_test_and_set(volatile int *ptr, int newval) {

  for (;;) {

      // Loop until success.

      int prev = *ptr;

      if (__m68k_cmpxchg (prev, newval, ptr) == prev)

        return prev;

    }

}

#endif // M68K

#ifdef ARM

/*

 * __kernel_cmpxchg

 *

 * Atomically store newval in *ptr if *ptr is equal to oldval for user space.

 * Return zero if *ptr was changed or non-zero if no exchange happened.

 * The C flag is also set if *ptr was changed to allow for assembly

 * optimization in the calling code.

 *

 */

typedef int (__kernel_cmpxchg_t)(int oldval, int newval, volatile int *ptr);

#define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) 0xffff0fc0)

/* Perform an atomic compare and swap: if the current value of `*PTR'

   is OLDVAL, then write NEWVAL into `*PTR'.  Return the contents of

   `*PTR' before the operation.*/

  for (;;) {

      int prev = *ptr;

      if (prev != oldval)

        return prev;

      if (__kernel_cmpxchg (prev, newval, ptr) == 0)

        // Success.

        return prev;

      // We failed even though prev == oldval.  Try again.

    }

}

/* Atomically add an int to memory.  */

static inline int arm_add_and_fetch(volatile int *ptr, int add_value) {

  for (;;) {

      // Loop until a __kernel_cmpxchg succeeds.

      int prev = *ptr;

      if (__kernel_cmpxchg (prev, prev + add_value, ptr) == 0)

        return prev + add_value;

    }

}

/* Atomically write VALUE into `*PTR' and returns the previous

   contents of `*PTR'.  */

static inline int arm_lock_test_and_set(volatile int *ptr, int newval) {

  for (;;) {

      // Loop until a __kernel_cmpxchg succeeds.

      int prev = *ptr;

      if (__kernel_cmpxchg (prev, newval, ptr) == 0)

        return prev;

    }

}

#endif // ARM

inline void Atomic::store(jint store_value, volatile jint* dest) {

  *dest = store_value;

}

inline void Atomic::store_ptr(intptr_t store_value, intptr_t* dest) {

  *dest = store_value;

}

inline jint Atomic::add(jint add_value, volatile jint* dest) {

#ifdef ARM

  return arm_add_and_fetch(dest, add_value);

#else

#ifdef M68K

  return m68k_add_and_fetch(dest, add_value);

#else

  return __sync_add_and_fetch(dest, add_value);

#endif // M68K

#endif // ARM

}

inline intptr_t Atomic::add_ptr(intptr_t add_value, volatile intptr_t* dest) {

#ifdef ARM

  return arm_add_and_fetch(dest, add_value);

#else

#ifdef M68K

  return m68k_add_and_fetch(dest, add_value);

#else

  return __sync_add_and_fetch(dest, add_value);

#endif // M68K

#endif // ARM

}

inline void* Atomic::add_ptr(intptr_t add_value, volatile void* dest) {

  return (void *) add_ptr(add_value, (volatile intptr_t *) dest);

}

inline void Atomic::inc(volatile jint* dest) {

  add(1, dest);

}

inline void Atomic::inc_ptr(volatile intptr_t* dest) {

  add_ptr(1, dest);

}

inline void Atomic::inc_ptr(volatile void* dest) {

  add_ptr(1, dest);

}

inline void Atomic::dec(volatile jint* dest) {

  add(-1, dest);

}

inline void Atomic::dec_ptr(volatile intptr_t* dest) {

  add_ptr(-1, dest);

}

inline void Atomic::dec_ptr(volatile void* dest) {

  add_ptr(-1, dest);

}

inline jint Atomic::xchg(jint exchange_value, volatile jint* dest) {

#ifdef ARM

  return arm_lock_test_and_set(dest, exchange_value);

#else

#ifdef M68K

  return m68k_lock_test_and_set(dest, exchange_value);

#else

  // __sync_lock_test_and_set is a bizarrely named atomic exchange

  // operation.  Note that some platforms only support this with the

  // limitation that the only valid value to store is the immediate

  // constant 1.  There is a test for this in JNI_CreateJavaVM().

  jint result = __sync_lock_test_and_set (dest, exchange_value);

  // All atomic operations are expected to be full memory barriers

  // (see atomic.hpp). However, __sync_lock_test_and_set is not

  // a full memory barrier, but an acquire barrier. Hence, this added

  // barrier.

  __sync_synchronize();

  return result;

#endif // M68K

#endif // ARM

}

inline intptr_t Atomic::xchg_ptr(intptr_t exchange_value,

                                 volatile intptr_t* dest) {

#ifdef ARM

  return arm_lock_test_and_set(dest, exchange_value);

#else

#ifdef M68K

  return m68k_lock_test_and_set(dest, exchange_value);

#else

  intptr_t result = __sync_lock_test_and_set (dest, exchange_value);

  __sync_synchronize();

  return result;

#endif // M68K

#endif // ARM

}

inline void* Atomic::xchg_ptr(void* exchange_value, volatile void* dest) {

  return (void *) xchg_ptr((intptr_t) exchange_value,

                           (volatile intptr_t*) dest);

}

#ifdef ARM

#else

#ifdef M68K

#else

  return __sync_val_compare_and_swap(dest, compare_value, exchange_value);

#endif // M68K

#endif // ARM

}

  return __sync_val_compare_and_swap(dest, compare_value, exchange_value);

}

inline jlong Atomic::load(const volatile jlong* src) {

  volatile jlong dest;

  os::atomic_copy64(src, &dest);

  return dest;

}

inline void Atomic::store(jlong store_value, jlong* dest) {

  os::atomic_copy64((volatile jlong*)&store_value, (volatile jlong*)dest);

}

inline void Atomic::store(jlong store_value, volatile jlong* dest) {

  os::atomic_copy64((volatile jlong*)&store_value, dest);

}

#endif // OS_CPU_LINUX_ZERO_VM_ATOMIC_LINUX_ZERO_HPP