1 // locks.h - Thread synchronization primitives. m68k implementation.
3 /* Copyright (C) 2006 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)
26 __asm__ __volatile__("cas.l %2,%3,%0; seq %1"
27 : "+m" (*addr), "=d" (result), "+d" (old)
33 // Set *addr to new_val with release semantics, i.e. making sure
34 // that prior loads and stores complete before this
36 // On m68k, the hardware shouldn't reorder reads and writes,
37 // so we just have to convince gcc not to do it either.
39 release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
41 __asm__ __volatile__(" " : : : "memory");
45 // Compare_and_swap with release semantics instead of acquire semantics.
46 // On many architecture, the operation makes both guarantees, so the
47 // implementation can be the same.
49 compare_and_swap_release(volatile obj_addr_t *addr,
53 return compare_and_swap(addr, old, new_val);
56 // Ensure that subsequent instructions do not execute on stale
57 // data that was loaded from memory before the barrier.
58 // On m68k, the hardware ensures that reads are properly ordered.
64 // Ensure that prior stores to memory are completed with respect to other
69 // m68k does not reorder writes. We just need to ensure that gcc also doesn't.
70 __asm__ __volatile__(" " : : : "memory");