1 files changed, 133 insertions, 0 deletions
diff --git a/libjava/sysdep/arm/locks.h b/libjava/sysdep/arm/locks.h
new file mode 100644
index 000000000..2a81e1111
--- /dev/null
+++ b/libjava/sysdep/arm/locks.h
@@ -0,0 +1,133 @@
+// locks.h - Thread synchronization primitives. ARM implementation.
+
+/* Copyright (C) 2007  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__
+
+typedef size_t obj_addr_t;	/* Integer type big enough for object	*/
+				/* address.				*/
+#if (__ARM_EABI__ && __linux)
+
+// 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();
+}
+
+#else
+
+/* Atomic compare and exchange.  These sequences are not actually
+   atomic; there is a race if *ADDR != OLD_VAL and we are preempted
+   between the two swaps.  However, they are very close to atomic, and
+   are the best that a pre-ARMv6 implementation can do without
+   operating system support.  LinuxThreads has been using these
+   sequences for many years.  */
+
+inline static bool
+compare_and_swap(volatile obj_addr_t *addr,
+		 obj_addr_t old_val,
+		 obj_addr_t new_val)
+{
+  volatile obj_addr_t result, tmp;
+  __asm__ ("\n"
+	   "0:	ldr	%[tmp],[%[addr]]\n"
+	   "	cmp	%[tmp],%[old_val]\n"
+	   "	movne	%[result],#0\n"
+	   "	bne	1f\n"
+	   "	swp	%[result],%[new_val],[%[addr]]\n"
+	   "	cmp	%[tmp],%[result]\n"
+	   "	swpne	%[tmp],%[result],[%[addr]]\n"
+	   "	bne	0b\n"
+	   "	mov	%[result],#1\n"
+	   "1:"
+	   : [result] "=&r" (result), [tmp] "=&r" (tmp)
+	   : [addr] "r" (addr), [new_val] "r" (new_val), [old_val] "r" (old_val)
+	   : "cc", "memory");
+
+  return result;
+}
+
+inline static void
+release_set(volatile obj_addr_t *addr, obj_addr_t new_val)
+{
+  __asm__ __volatile__("" : : : "memory");
+  *(addr) = new_val;
+}
+
+inline static bool
+compare_and_swap_release(volatile obj_addr_t *addr,
+			 obj_addr_t old,
+			 obj_addr_t new_val)
+{
+  return 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.
+inline static void
+read_barrier()
+{
+  __asm__ __volatile__("" : : : "memory");
+}
+
+// Ensure that prior stores to memory are completed with respect to other
+// processors.
+inline static void
+write_barrier()
+{
+  __asm__ __volatile__("" : : : "memory");
+}
+
+#endif
+#endif