Subversion Repositories openrisc

// locks.h - Thread synchronization primitives. MIPS implementation.

/* Copyright (C) 2003  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the

Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for

details.  */

#ifndef __SYSDEP_LOCKS_H__

#define __SYSDEP_LOCKS_H__

/* Integer type big enough for object address.  */

typedef unsigned obj_addr_t __attribute__((__mode__(__pointer__)));

// Atomically replace *addr by new_val if it was initially equal to old.

// Return true if the comparison succeeded.

// Assumed to have acquire semantics, i.e. later memory operations

// cannot execute before the compare_and_swap finishes.

inline static bool

compare_and_swap(volatile obj_addr_t *addr,

                 obj_addr_t old,

                 obj_addr_t new_val)

{

  return __sync_bool_compare_and_swap(addr, old, new_val);

}

// Set *addr to new_val with release semantics, i.e. making sure

// that prior loads and stores complete before this

// assignment.

inline static void

release_set(volatile obj_addr_t *addr, obj_addr_t new_val)

{

  __sync_synchronize();

  *(addr) = new_val;

}

// Compare_and_swap with release semantics instead of acquire semantics.

// On many architecture, the operation makes both guarantees, so the

// implementation can be the same.

inline static bool

compare_and_swap_release(volatile obj_addr_t *addr,

                         obj_addr_t old,

                         obj_addr_t new_val)

{

  return __sync_bool_compare_and_swap(addr, old, new_val);

}

// Ensure that subsequent instructions do not execute on stale

// data that was loaded from memory before the barrier.

// On X86, the hardware ensures that reads are properly ordered.

inline static void

read_barrier()

{

  __sync_synchronize();

}

// Ensure that prior stores to memory are completed with respect to other

// processors.

inline static void

write_barrier()

{

  __sync_synchronize();

}

#endif   // __SYSDEP_LOCKS_H__