274 lines
7.8 KiB
C
274 lines
7.8 KiB
C
/*
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* Copyright (c) 2004, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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*/
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/** \addtogroup sys
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* @{
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*/
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/**
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* \defgroup mt Multi-threading library
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*
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* The event driven Contiki kernel does not provide multi-threading
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* by itself - instead, preemptive multi-threading is implemented
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* 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
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* the same for all platforms on which Contiki runs, and a platform
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* specific part, which must be implemented specifically for the
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* platform that the multi-threading library should run.
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*
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* @{
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*/
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/**
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* \defgroup mtarch Architecture support for multi-threading
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* @{
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*
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* The Contiki multi-threading library requires some architecture
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* specific support for setting up and switching stacks. This support
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* requires four stack manipulation functions to be implemented:
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* mtarch_start(), which sets up the stack frame for a new thread,
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* mtarch_exec(), which switches in the stack of a thread,
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* mtarch_yield(), which restores the kernel stack from a thread's
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* stack and mtarch_stop(), which cleans up the stack of a thread.
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* Additionally, two functions for controlling the preemption
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* (if any) must be implemented: mtarch_pstart() and mtarch_pstop().
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* If no preemption is used, these functions can be implemented as
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* 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,
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* or any other mechanisms required for correct operation of the
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* architecture specific support functions while mtarch_remove() is
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* called by mt_remove() to clean up those resources.
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*
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*/
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/**
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* \file
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* Header file for the preemptive multitasking library for Contiki.
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* \author
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* Adam Dunkels <adam@sics.se>
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*
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*/
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#ifndef MT_H_
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#define MT_H_
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#include "contiki.h"
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#define MT_STATE_READY 1
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#define MT_STATE_RUNNING 2
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#define MT_STATE_EXITED 5
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/**
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* An opaque structure that is used for holding the state of a thread.
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*
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* The structure should be defined in the "mtarch.h" file. This
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* structure typically holds the entire stack for the thread.
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*/
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struct mtarch_thread;
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/**
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* Initialize the architecture specific support functions for the
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* multi-thread library.
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*
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* This function is implemented by the architecture specific functions
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* for the multi-thread library and is called by the mt_init()
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* 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
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* timers or other architecture specific mechanisms required for the
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* operation of the library.
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*/
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void mtarch_init(void);
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/**
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* Uninstall library and clean up.
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*
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*/
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void mtarch_remove(void);
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/**
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* Setup the stack frame for a thread that is being started.
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*
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* This function is called by the mt_start() function in order to set
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* up the architecture specific stack of the thread to be started.
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*
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* \param thread A pointer to a struct mtarch_thread for the thread to
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* be started.
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*
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* \param function A pointer to the function that the thread will
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* start executing the first time it is scheduled to run.
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*
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* \param data A pointer to the argument that the function should be
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* passed.
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*/
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void mtarch_start(struct mtarch_thread *thread,
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void (* function)(void *data),
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void *data);
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/**
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* Start executing a thread.
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*
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* This function is called from mt_exec() and the purpose of the
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* function is to start execution of the thread. The function should
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* switch in the stack of the thread, and does not return until the
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* thread has explicitly yielded (using mt_yield()) or until it is
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* preempted.
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*
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* \param thread A pointer to a struct mtarch_thread for the thread to
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* be executed.
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*
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*/
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void mtarch_exec(struct mtarch_thread *thread);
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/**
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* Yield the processor.
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*
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* This function is called by the mt_yield() function, which is called
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* from the running thread in order to give up the processor.
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*
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*/
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void mtarch_yield(void);
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/**
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* Clean up the stack of a thread.
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*
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* This function is called by the mt_stop() function in order to clean
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* up the architecture specific stack of the thread to be stopped.
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*
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* \note If the stack is wholly contained in struct mtarch_thread this
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* function may very well be empty.
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*
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* \param thread A pointer to a struct mtarch_thread for the thread to
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* be stopped.
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*
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*/
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void mtarch_stop(struct mtarch_thread *thread);
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void mtarch_pstart(void);
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void mtarch_pstop(void);
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/** @} */
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#include "mtarch.h"
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struct mt_thread {
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int state;
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process_event_t *evptr;
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process_data_t *dataptr;
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struct mtarch_thread thread;
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};
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/**
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* No error.
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*
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* \hideinitializer
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*/
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#define MT_OK 1
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/**
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* Initializes the multithreading library.
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*
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*/
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void mt_init(void);
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/**
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* Uninstalls library and cleans up.
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*
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*/
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void mt_remove(void);
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/**
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* Starts a multithreading thread.
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*
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* \param thread Pointer to an mt_thread struct that must have been
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* previously allocated by the caller.
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*
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* \param function A pointer to the entry function of the thread that is
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* to be set up.
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*
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* \param data A pointer that will be passed to the entry function.
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*
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*/
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void mt_start(struct mt_thread *thread, void (* function)(void *), void *data);
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/**
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* Execute parts of a thread.
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*
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* This function is called by a Contiki process and runs a
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* thread. The function does not return until the thread has yielded,
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* or is preempted.
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*
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* \note The thread library must first be initialized with the mt_init()
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* function.
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*
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* \param thread A pointer to a struct mt_thread block that must be
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* allocated by the caller.
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*
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*/
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void mt_exec(struct mt_thread *thread);
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/**
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* Voluntarily give up the processor.
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*
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* This function is called by a running thread in order to give up
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* control of the CPU.
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*
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*/
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void mt_yield(void);
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/**
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* Exit a thread.
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*
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* This function is called from within an executing thread in order to
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* exit the thread. The function never returns.
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*
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*/
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void mt_exit(void);
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/**
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* Stop a thread.
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*
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* This function is called by a Contiki process in order to clean up a
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* thread. The struct mt_thread block may then be discarded by the caller.
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*
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* \param thread A pointer to a struct mt_thread block that must be
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* allocated by the caller.
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*
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*/
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void mt_stop(struct mt_thread *thread);
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/** @} */
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/** @} */
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#endif /* MT_H_ */
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