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diff --git a/i386/include/mach/proc_ops.h b/i386/include/mach/proc_ops.h
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+++ b/i386/include/mach/proc_ops.h
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+/*
+ * Copyright (c) 1994 The University of Utah and
+ * the Center for Software Science (CSS).  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.
+ *
+ * THE UNIVERSITY OF UTAH AND CSS ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSS DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSS requests users of this software to return to css-dist@cs.utah.edu any
+ * improvements that they make and grant CSS redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSS
+ */
+#ifndef _MACH_I386_PROC_OPS_H_
+#define _MACH_I386_PROC_OPS_H_
+
+#include <mach/machine/vm_types.h>
+#include <mach/inline.h>
+
+/* Returns the bit number of the most-significant set bit in `val',
+   e.g. 0 for 1, 1 for 2-3, 2 for 4-7, etc.
+   If `val' is 0 (i.e. no bits are set), the behavior is undefined.  */
+MACH_INLINE int find_msb_set(natural_t val)
+{
+	int msb;
+
+	asm("
+		bsr	%0,%0
+	" : "=r" (msb) : "0" (val));
+
+	return msb;
+}
+
+#endif _MACH_I386_PROC_OPS_H_