1 files changed, 33 insertions, 0 deletions
diff --git a/lib/libc_r/arch/alpha/_atomic_lock.c b/lib/libc_r/arch/alpha/_atomic_lock.c
new file mode 100644
index 00000000000..74575fc11d7
--- /dev/null
+++ b/lib/libc_r/arch/alpha/_atomic_lock.c
@@ -0,0 +1,33 @@
+/*	$OpenBSD: _atomic_lock.c,v 1.1 1998/11/20 11:15:35 d Exp $	*/
+/* Atomic lock for alpha */
+
+#include "spinlock.h"
+
+register_t
+_atomic_lock(volatile register_t * lock)
+{
+	register_t old;
+	register_t new;
+	int success;
+
+	do {
+		/* load the value of the thread-lock (lock mem on load) */
+		__asm__( "ldq_l %0, %1" : "=r"(old) : "m"(*lock) );
+		if (old) 
+			new = old;	/* in-use: put it back */
+		else
+			new = 1;	/* free: store a 1 in the lock */
+
+		success = 0;
+		/* store the new value of the thrd-lock (unlock mem on store) */
+		/*
+		 * XXX may need to add large branch forward for main line
+		 * branch prediction to be right :(
+		 */
+		__asm__( "stq_c %2, %0; beq %2, 1f; mov 1,%1; 1:"
+					: "=m"(*lock), "=r"(success)
+					: "r"(new) );
+	} while (!success);
+
+	return old;
+}