Diff: pt.h

Revision:

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+++ b/pt.h	Tue Nov 30 22:19:29 2010 +0000
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+/*
+ * Copyright (c) 2004-2005, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 THE INSTITUTE 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.
+ *
+ * This file is part of the Contiki operating system.
+ *
+ * Author: Adam Dunkels <adam@sics.se>
+ *
+ * $Id: pt.h,v 1.7 2006/10/02 07:52:56 adam Exp $
+ */
+
+/**
+ * \addtogroup pt
+ * @{
+ */
+
+/**
+ * \file
+ * Protothreads implementation.
+ * \author
+ * Adam Dunkels <adam@sics.se>
+ *
+ */
+
+#ifndef __PT_H__
+#define __PT_H__
+
+#include "lc.h"
+
+struct pt {
+  lc_t lc;
+};
+
+#define PT_WAITING 0
+#define PT_YIELDED 1
+#define PT_EXITED  2
+#define PT_ENDED   3
+
+/**
+ * \name Initialization
+ * @{
+ */
+
+/**
+ * Initialize a protothread.
+ *
+ * Initializes a protothread. Initialization must be done prior to
+ * starting to execute the protothread.
+ *
+ * \param pt A pointer to the protothread control structure.
+ *
+ * \sa PT_SPAWN()
+ *
+ * \hideinitializer
+ */
+#define PT_INIT(pt)   LC_INIT((pt)->lc)
+
+/** @} */
+
+/**
+ * \name Declaration and definition
+ * @{
+ */
+
+/**
+ * Declaration of a protothread.
+ *
+ * This macro is used to declare a protothread. All protothreads must
+ * be declared with this macro.
+ *
+ * \param name_args The name and arguments of the C function
+ * implementing the protothread.
+ *
+ * \hideinitializer
+ */
+#define PT_THREAD(name_args) char name_args
+
+/**
+ * Declare the start of a protothread inside the C function
+ * implementing the protothread.
+ *
+ * This macro is used to declare the starting point of a
+ * protothread. It should be placed at the start of the function in
+ * which the protothread runs. All C statements above the PT_BEGIN()
+ * invokation will be executed each time the protothread is scheduled.
+ *
+ * \param pt A pointer to the protothread control structure.
+ *
+ * \hideinitializer
+ */
+#define PT_BEGIN(pt) { char PT_YIELD_FLAG = 1; LC_RESUME((pt)->lc)
+
+/**
+ * Declare the end of a protothread.
+ *
+ * This macro is used for declaring that a protothread ends. It must
+ * always be used together with a matching PT_BEGIN() macro.
+ *
+ * \param pt A pointer to the protothread control structure.
+ *
+ * \hideinitializer
+ */
+#define PT_END(pt) LC_END((pt)->lc); PT_YIELD_FLAG = 0; \
+                   PT_INIT(pt); return PT_ENDED; }
+
+/** @} */
+
+/**
+ * \name Blocked wait
+ * @{
+ */
+
+/**
+ * Block and wait until condition is true.
+ *
+ * This macro blocks the protothread until the specified condition is
+ * true.
+ *
+ * \param pt A pointer to the protothread control structure.
+ * \param condition The condition.
+ *
+ * \hideinitializer
+ */
+#define PT_WAIT_UNTIL(pt, condition)	        \
+  do {						\
+    LC_SET((pt)->lc);				\
+    if(!(condition)) {				\
+      return PT_WAITING;			\
+    }						\
+  } while(0)
+
+/**
+ * Block and wait while condition is true.
+ *
+ * This function blocks and waits while condition is true. See
+ * PT_WAIT_UNTIL().
+ *
+ * \param pt A pointer to the protothread control structure.
+ * \param cond The condition.
+ *
+ * \hideinitializer
+ */
+#define PT_WAIT_WHILE(pt, cond)  PT_WAIT_UNTIL((pt), !(cond))
+
+/** @} */
+
+/**
+ * \name Hierarchical protothreads
+ * @{
+ */
+
+/**
+ * Block and wait until a child protothread completes.
+ *
+ * This macro schedules a child protothread. The current protothread
+ * will block until the child protothread completes.
+ *
+ * \note The child protothread must be manually initialized with the
+ * PT_INIT() function before this function is used.
+ *
+ * \param pt A pointer to the protothread control structure.
+ * \param thread The child protothread with arguments
+ *
+ * \sa PT_SPAWN()
+ *
+ * \hideinitializer
+ */
+#define PT_WAIT_THREAD(pt, thread) PT_WAIT_WHILE((pt), PT_SCHEDULE(thread))
+
+/**
+ * Spawn a child protothread and wait until it exits.
+ *
+ * This macro spawns a child protothread and waits until it exits. The
+ * macro can only be used within a protothread.
+ *
+ * \param pt A pointer to the protothread control structure.
+ * \param child A pointer to the child protothread's control structure.
+ * \param thread The child protothread with arguments
+ *
+ * \hideinitializer
+ */
+#define PT_SPAWN(pt, child, thread)		\
+  do {						\
+    PT_INIT((child));				\
+    PT_WAIT_THREAD((pt), (thread));		\
+  } while(0)
+
+/** @} */
+
+/**
+ * \name Exiting and restarting
+ * @{
+ */
+
+/**
+ * Restart the protothread.
+ *
+ * This macro will block and cause the running protothread to restart
+ * its execution at the place of the PT_BEGIN() call.
+ *
+ * \param pt A pointer to the protothread control structure.
+ *
+ * \hideinitializer
+ */
+#define PT_RESTART(pt)				\
+  do {						\
+    PT_INIT(pt);				\
+    return PT_WAITING;			\
+  } while(0)
+
+/**
+ * Exit the protothread.
+ *
+ * This macro causes the protothread to exit. If the protothread was
+ * spawned by another protothread, the parent protothread will become
+ * unblocked and can continue to run.
+ *
+ * \param pt A pointer to the protothread control structure.
+ *
+ * \hideinitializer
+ */
+#define PT_EXIT(pt)				\
+  do {						\
+    PT_INIT(pt);				\
+    return PT_EXITED;			\
+  } while(0)
+
+/** @} */
+
+/**
+ * \name Calling a protothread
+ * @{
+ */
+
+/**
+ * Schedule a protothread.
+ *
+ * This function shedules a protothread. The return value of the
+ * function is non-zero if the protothread is running or zero if the
+ * protothread has exited.
+ *
+ * \param f The call to the C function implementing the protothread to
+ * be scheduled
+ *
+ * \hideinitializer
+ */
+#define PT_SCHEDULE(f) ((f) < PT_EXITED)
+
+/** @} */
+
+/**
+ * \name Yielding from a protothread
+ * @{
+ */
+
+/**
+ * Yield from the current protothread.
+ *
+ * This function will yield the protothread, thereby allowing other
+ * processing to take place in the system.
+ *
+ * \param pt A pointer to the protothread control structure.
+ *
+ * \hideinitializer
+ */
+#define PT_YIELD(pt)				\
+  do {						\
+    PT_YIELD_FLAG = 0;				\
+    LC_SET((pt)->lc);				\
+    if(PT_YIELD_FLAG == 0) {			\
+      return PT_YIELDED;			\
+    }						\
+  } while(0)
+
+/**
+ * \brief      Yield from the protothread until a condition occurs.
+ * \param pt   A pointer to the protothread control structure.
+ * \param cond The condition.
+ *
+ *             This function will yield the protothread, until the
+ *             specified condition evaluates to true.
+ *
+ *
+ * \hideinitializer
+ */
+#define PT_YIELD_UNTIL(pt, cond)		\
+  do {						\
+    PT_YIELD_FLAG = 0;				\
+    LC_SET((pt)->lc);				\
+    if((PT_YIELD_FLAG == 0) || !(cond)) {	\
+      return PT_YIELDED;			\
+    }						\
+  } while(0)
+
+/** @} */
+
+#endif /* __PT_H__ */
+
+/** @} */