Initial source

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diff --git a/kern/shuttle.h b/kern/shuttle.h
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+/*
+ * Copyright (c) 1993,1994 The University of Utah and
+ * the Computer Systems Laboratory (CSL).  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 CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ *      Author: Bryan Ford, University of Utah CSL
+ */
+/*
+ *	File:	shuttle.h
+ *	Author:	Bryan Ford
+ *
+ *	This file contains definitions for shuttles,
+ *	which handle microscheduling for individual threads.
+ *
+ */
+
+#ifndef	_KERN_SHUTTLE_H_
+#define _KERN_SHUTTLE_H_
+
+#include <kern/lock.h>
+
+
+
+struct Shuttle {
+	/* XXX must be first in thread */
+/*
+ *	NOTE:	The runq field in the thread structure has an unusual
+ *	locking protocol.  If its value is RUN_QUEUE_NULL, then it is
+ *	locked by the thread_lock, but if its value is something else
+ *	(i.e. a run_queue) then it is locked by that run_queue's lock.
+ */
+	queue_chain_t	links;		/* current run queue links */
+	run_queue_t	runq;		/* run queue p is on SEE BELOW */
+
+	/* Next pointer when on a queue */
+	struct Shuttle *next;
+
+	/* Micropriority level */
+	int priority;
+
+	/* General-purpose pointer field whose use depends on what the
+	   thread happens to be doing */
+	void		*message;
+
+	int foobar[1];
+};
+typedef struct Shuttle Shuttle;
+
+
+
+/* Exported functions */
+
+
+
+/* Machine-dependent code must define the following functions */
+
+
+
+#endif	_KERN_SHUTTLE_H_