1 // locks.h - Thread synchronization primitives. m68k implementation.
3 /* Copyright (C) 2006, 2012 Free Software Foundation
5 This file is part of libgcj.
7 This software is copyrighted work licensed under the terms of the
8 Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
11 #ifndef __SYSDEP_LOCKS_H__
12 #define __SYSDEP_LOCKS_H__
14 /* Integer type big enough for object address. */
15 typedef size_t obj_addr_t
__attribute__ ((aligned (4)));
17 // Atomically replace *addr by new_val if it was initially equal to old.
18 // Return true if the comparison succeeded.
19 // Assumed to have acquire semantics, i.e. later memory operations
20 // cannot execute before the compare_and_swap finishes.
22 compare_and_swap(volatile obj_addr_t
*addr
,
23 obj_addr_t old
, obj_addr_t new_val
)
25 return __sync_bool_compare_and_swap (addr
, old
, new_val
);
28 // Ensure that subsequent instructions do not execute on stale
29 // data that was loaded from memory before the barrier.
30 // On m68k, the hardware ensures that reads are properly ordered.
36 // Ensure that prior stores to memory are completed with respect to other
41 // m68k does not reorder writes. We just need to ensure that gcc also doesn't.
42 __asm__
__volatile__(" " : : : "memory");
45 // Set *addr to new_val with release semantics, i.e. making sure
46 // that prior loads and stores complete before this
48 // On m68k, the hardware shouldn't reorder reads and writes,
49 // so we just have to convince gcc not to do it either.
51 release_set(volatile obj_addr_t
*addr
, obj_addr_t new_val
)
57 // Compare_and_swap with release semantics instead of acquire semantics.
58 // On many architecture, the operation makes both guarantees, so the
59 // implementation can be the same.
61 compare_and_swap_release(volatile obj_addr_t
*addr
,
65 return compare_and_swap(addr
, old
, new_val
);