/* * 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 * 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 * 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 * mt_init(), and can be used for initialization of timer interrupts, * or any other mechanisms required for correct operation of the * 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" /** * 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 * 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_ */