entered into RCS

1 files changed, 70 insertions, 0 deletions

diff --git a/libthreads/i386/lock.s b/libthreads/i386/lock.s
new file mode 100644
index 00000000..e27fa7ff
--- /dev/null
+++ b/libthreads/i386/lock.s
@@ -0,0 +1,70 @@
+/* 
+ * Mach Operating System
+ * Copyright (c) 1991,1990 Carnegie Mellon University
+ * All Rights Reserved.
+ * 
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ * 
+ * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
+ * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
+ * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ * 
+ * Carnegie Mellon requests users of this software to return to
+ * 
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ * 
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+/*
+ * HISTORY
+ * $Log:	lock.s,v $
+ * Revision 2.5  91/05/14  17:57:20  mrt
+ * 	Correcting copyright
+ * 
+ * Revision 2.4  91/05/08  13:36:15  dbg
+ * 	Unlock lock with a locked instruction (xchg).
+ * 	[91/03/20            dbg]
+ * 
+ * Revision 2.3  91/02/14  14:20:18  mrt
+ * 	Changed to new Mach copyright
+ * 	[91/02/13  12:20:06  mrt]
+ * 
+ * Revision 2.2  90/05/03  15:54:59  dbg
+ * 	Created.
+ * 	[90/02/05            dbg]
+ * 
+ */
+
+#include <i386/asm.h>
+
+/*
+ * boolean_t spin_try_lock(int *m)
+ */
+ENTRY(spin_try_lock)
+	movl	4(%esp),%ecx		/ point at mutex
+	movl	$1,%eax			/ set locked value in acc
+	xchg	%eax,(%ecx)		/ swap with mutex
+					/ xchg with memory is automatically
+					/ locked
+	xorl	$1,%eax			/ 1 (locked) => FALSE
+					/ 0 (locked) => TRUE
+	ret
+
+/*
+ * void spin_unlock(int *m)
+ */
+ENTRY(spin_unlock)
+	movl	4(%esp),%ecx		/ point at mutex
+	xorl	%eax,%eax		/ set unlocked value in acc
+	xchg	%eax,(%ecx)		/ swap with mutex
+					/ xchg with memory is automatically
+					/ locked
+	ret