contiki/core/sys/mt.h

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/*
* Copyright (c) 2004, 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>
*
*/
/** \addtogroup sys
* @{
*/
/**
* \defgroup mt Multi-threading library
*
* The event driven Contiki kernel does not provide multi-threading
* by itself - instead, preemptive multi-threading is implemented
* as a library that optionally can be linked with applications. This
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* library consists of two parts: a platform independent part, which is
* the same for all platforms on which Contiki runs, and a platform
* specific part, which must be implemented specifically for the
* platform that the multi-threading library should run.
*
* @{
*/
/**
* \defgroup mtarch Architecture support for multi-threading
* @{
*
* The Contiki multi-threading library requires some architecture
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* specific support for setting up and switching stacks. This support
* requires four stack manipulation functions to be implemented:
* mtarch_start(), which sets up the stack frame for a new thread,
* mtarch_exec(), which switches in the stack of a thread,
* mtarch_yield(), which restores the kernel stack from a thread's
* stack and mtarch_stop(), which cleans up the stack of a thread.
* Additionally, two functions for controlling the preemption
* (if any) must be implemented: mtarch_pstart() and mtarch_pstop().
* If no preemption is used, these functions can be implemented as
* empty functions. Finally, the function mtarch_init() is called by
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* mt_init(), and can be used for initialization of timer interrupts,
* or any other mechanisms required for correct operation of the
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* architecture specific support functions while mtarch_remove() is
* called by mt_remove() to clean up those resources.
*
*/
/**
* \file
* Header file for the preemptive multitasking library for Contiki.
* \author
* Adam Dunkels <adam@sics.se>
*
*/
#ifndef MT_H_
#define MT_H_
#include "contiki.h"
#define MT_STATE_READY 1
#define MT_STATE_RUNNING 2
#define MT_STATE_EXITED 5
/**
* An opaque structure that is used for holding the state of a thread.
*
* The structure should be defined in the "mtarch.h" file. This
* structure typically holds the entire stack for the thread.
*/
struct mtarch_thread;
/**
* Initialize the architecture specific support functions for the
* multi-thread library.
*
* This function is implemented by the architecture specific functions
* for the multi-thread library and is called by the mt_init()
* function as part of the initialization of the library. The
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* mtarch_init() function can be used for, e.g., starting preemption
* timers or other architecture specific mechanisms required for the
* operation of the library.
*/
void mtarch_init(void);
/**
* Uninstall library and clean up.
*
*/
void mtarch_remove(void);
/**
* Setup the stack frame for a thread that is being started.
*
* This function is called by the mt_start() function in order to set
* up the architecture specific stack of the thread to be started.
*
* \param thread A pointer to a struct mtarch_thread for the thread to
* be started.
*
* \param function A pointer to the function that the thread will
* start executing the first time it is scheduled to run.
*
* \param data A pointer to the argument that the function should be
* passed.
*/
void mtarch_start(struct mtarch_thread *thread,
void (* function)(void *data),
void *data);
/**
* Start executing a thread.
*
* This function is called from mt_exec() and the purpose of the
* function is to start execution of the thread. The function should
* switch in the stack of the thread, and does not return until the
* thread has explicitly yielded (using mt_yield()) or until it is
* preempted.
*
* \param thread A pointer to a struct mtarch_thread for the thread to
* be executed.
*
*/
void mtarch_exec(struct mtarch_thread *thread);
/**
* Yield the processor.
*
* This function is called by the mt_yield() function, which is called
* from the running thread in order to give up the processor.
*
*/
void mtarch_yield(void);
/**
* Clean up the stack of a thread.
*
* This function is called by the mt_stop() function in order to clean
* up the architecture specific stack of the thread to be stopped.
*
* \note If the stack is wholly contained in struct mtarch_thread this
* function may very well be empty.
*
* \param thread A pointer to a struct mtarch_thread for the thread to
* be stopped.
*
*/
void mtarch_stop(struct mtarch_thread *thread);
void mtarch_pstart(void);
void mtarch_pstop(void);
/** @} */
#include "mtarch.h"
struct mt_thread {
int state;
process_event_t *evptr;
process_data_t *dataptr;
struct mtarch_thread thread;
};
/**
* No error.
*
* \hideinitializer
*/
#define MT_OK 1
/**
* Initializes the multithreading library.
*
*/
void mt_init(void);
/**
* Uninstalls library and cleans up.
*
*/
void mt_remove(void);
/**
* Starts a multithreading thread.
*
* \param thread Pointer to an mt_thread struct that must have been
* previously allocated by the caller.
*
* \param function A pointer to the entry function of the thread that is
* to be set up.
*
* \param data A pointer that will be passed to the entry function.
*
*/
void mt_start(struct mt_thread *thread, void (* function)(void *), void *data);
/**
* Execute parts of a thread.
*
* This function is called by a Contiki process and runs a
* thread. The function does not return until the thread has yielded,
* or is preempted.
*
* \note The thread library must first be initialized with the mt_init()
* function.
*
* \param thread A pointer to a struct mt_thread block that must be
* allocated by the caller.
*
*/
void mt_exec(struct mt_thread *thread);
/**
* Voluntarily give up the processor.
*
* This function is called by a running thread in order to give up
* control of the CPU.
*
*/
void mt_yield(void);
/**
* Exit a thread.
*
* This function is called from within an executing thread in order to
* exit the thread. The function never returns.
*
*/
void mt_exit(void);
/**
* Stop a thread.
*
* This function is called by a Contiki process in order to clean up a
* thread. The struct mt_thread block may then be discarded by the caller.
*
* \param thread A pointer to a struct mt_thread block that must be
* allocated by the caller.
*
*/
void mt_stop(struct mt_thread *thread);
/** @} */
/** @} */
#endif /* MT_H_ */