Atomic lock asm code for the alpha version of libc_r.

1 files changed, 57 insertions, 0 deletions

diff --git a/lib/libc_r/arch/alpha/_atomic_lock.S b/lib/libc_r/arch/alpha/_atomic_lock.S
new file mode 100644
index 0000000..7ca46f7
--- /dev/null
+++ b/lib/libc_r/arch/alpha/_atomic_lock.S
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
+ * All rights reserved.
+ * copyright Douglas Santry 1996
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the above copyright is retained
+ * in the source form.
+ *
+ * THIS SOFTWARE IS PROVIDED BY Douglas Santry AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE  
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE   
+ * ARE DISCLAIMED.  IN NO EVENT SHALL Douglas Santry OR CONTRIBUTORS BE LIABLE 
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL   
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS      
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF  
+ * SUCH DAMAGE.    
+ *
+ * $Id: _atomic_lock.S,v 1.1 1998/04/29 09:36:03 jb Exp $
+ *
+ */
+
+#include "SYS.h"
+
+/*
+ * Atomicly lock a location with an identifier provided the location
+ * is not currently locked.
+ *
+ * long _atomic_lock(long *);
+ * v0 will contain the return value (zero if lock obtained).
+ */
+LEAF(_atomic_lock,0)
+	LDGP(pv)
+
+	/* Get the existing lock value and lock memory: */
+	ldq_l	v0, 0(a0)
+
+	/* Branch if already locked: */
+	bne	v0, already_locked
+
+	/* Not locked, so store 1: */
+	mov	1, t0
+	stq_c	t0, 0(a0)
+
+	/* Obtained the lock: */
+	br	done
+
+already_locked:
+	/* Already locked so put the value back and unlock memory: */
+	stq_c	v0, 0(a0)
+	
+done:
+	RET
+END(_atomic_lock)