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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_