Initial code for a Contiki real-time scheduler
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adamdunkels
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153
core/sys/rt.c
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153
core/sys/rt.c
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/*
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* Copyright (c) 2005, 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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* @(#)$Id: rt.c,v 1.1 2007/03/19 00:16:13 adamdunkels Exp $
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*/
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#include "sys/rt.h"
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#include "contiki.h"
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#define LIST_SIZE 16
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static struct rt_task *tasks[LIST_SIZE];
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static u8_t next, firstempty;
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#define DEBUG 0
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#if DEBUG
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#include <stdio.h>
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#define PRINTF(...) printf(__VA_ARGS__)
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#else
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#define PRINTF(...)
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#endif
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/*---------------------------------------------------------------------------*/
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void
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rt_init(void)
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{
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next = 0;
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firstempty = 0;
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rt_arch_init();
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}
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/*---------------------------------------------------------------------------*/
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int
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rt_post(struct rt_task *task, rt_clock_t time, rt_clock_t duration)
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{
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int i;
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PRINTF("rt_post time %d\n", time);
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/* Check if task queue is full. */
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if(firstempty == (next - 1) % LIST_SIZE) {
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PRINTF("rt_post: next %d firstempty %d full\n", next, firstempty);
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return RT_ERR_FULL;
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}
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/* Check if it is possible to run this task at the requested
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time. */
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for(i = next; i != firstempty;
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i = (i + 1) % LIST_SIZE) {
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/* XXX: should check a range of time not just the same precise
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moment. */
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if(tasks[i]->time == time) {
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PRINTF("rt_post: next %d firstempty %d time %d == %d\n",
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next, firstempty, tasks[i]->time, time);
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return RT_ERR_TIME;
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}
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}
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/* Put the task at the end of the task list. */
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task->time = time;
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tasks[firstempty] = task;
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PRINTF("rt_post: putting task %s as %d\n", task->name, firstempty);
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firstempty = (firstempty + 1) % LIST_SIZE;
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/* PRINTF("rt_post: next %d firstempty %d scheduling soon\n",
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next, firstempty);*/
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/* Check if this is the first task on the list. If so, we need to
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run the rt_arch_schedule() function to get the ball rolling. */
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if(firstempty == (next + 1) % LIST_SIZE) {
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PRINTF("rt_post scheduling %d %s (%d)\n",
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next, tasks[next]->name, tasks[next]->time);
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rt_arch_schedule(time);
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}
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return RT_OK;
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}
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/*---------------------------------------------------------------------------*/
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void
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rt_task_run(void)
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{
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int i, n;
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struct rt_task *t;
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t = tasks[next];
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/* Increase the pointer to the next task. */
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next = (next + 1) % LIST_SIZE;
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/* Run the task. */
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PRINTF("rt_task_run running %s\n", t->name);
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t->func(t, t->ptr);
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if(next == firstempty) {
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PRINTF("rt_task_run: empty task list\n");
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/* The list is empty, no more tasks to schedule. */
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return;
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}
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/* Find the next task to run. */
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n = next;
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for(i = next; i != firstempty; i = (i + 1) % LIST_SIZE) {
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PRINTF("rt_task_run checking %s (%d) against %s (%d)\n",
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tasks[i]->name, tasks[i]->time,
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tasks[n]->name, tasks[n]->time);
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if(tasks[i]->prio >= tasks[n]->prio &&
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RT_CLOCK_LT(tasks[i]->time, tasks[n]->time)) {
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n = i;
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}
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}
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PRINTF("rt_task_run next task is %d %s (%d)\n",
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n, tasks[n]->name, tasks[n]->time);
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/* Put the next task first in the task list. */
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t = tasks[next];
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tasks[next] = tasks[n];
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tasks[n] = t;
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PRINTF("rt_task_run scheduling %d %s (%d)\n",
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next, tasks[next]->name, tasks[next]->time);
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rt_arch_schedule(tasks[next]->time);
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}
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/*---------------------------------------------------------------------------*/
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156
core/sys/rt.h
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156
core/sys/rt.h
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@ -0,0 +1,156 @@
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/**
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* \defgroup rt Real-time task scheduling
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*
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* The real-time module handles the scheduling and execution of
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* real-time tasks (with predictible execution times).
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*
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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 real-time module.
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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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/*
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* Copyright (c) 2005, 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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* @(#)$Id: rt.h,v 1.1 2007/03/19 00:16:13 adamdunkels Exp $
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*/
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#ifndef __RT_H__
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#define __RT_H__
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typedef unsigned short rt_clock_t;
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#define RT_CLOCK_LT(a,b) ((signed short)((a)-(b)) < 0)
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/**
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* \brief Initialize the real-time scheduler.
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*
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* This function initializes the real-time scheduler and
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* must be called at boot-up, before any other functions
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* from the real-time scheduler is called.
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*/
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void rt_init(void);
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/**
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* \brief Repressentation of a real-time task
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*
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* This structure represents a real-time task and is used
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* by the real-time module and the architecture specific
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* support module for the real-time module.
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*/
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struct rt_task {
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char *name;
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rt_clock_t time;
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void (* func)(struct rt_task *t, void *ptr);
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unsigned char prio;
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void *ptr;
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};
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/**
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* \brief Declare a real-time task.
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* \param name The name of the task state variable.
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* \param func The function implementing the real-time task.
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* \param prio The priority of the task.
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* \param ptr An opaque pointer that is passed to the real-time task
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* when it is executed.
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*
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* This macro declares a real-time task.
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*
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* \hideinitializer
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*/
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#define RT_TASK(name, func, prio, ptr) { name, 0, func, prio, ptr }
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enum {
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RT_OK,
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RT_ERR_FULL,
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RT_ERR_TIME,
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};
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/**
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* \brief Post a real-time task.
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* \param task A pointer to the task variable previously declared with RT_TASK().
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* \param time The time when the task is to be executed.
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* \return Non-zero (true) if the task could be scheduled, zero
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* (false) if the task could not be scheduled.
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*
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* This function schedules a real-time task a specified
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* time in the future.
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*
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*/
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int rt_post(struct rt_task *task, rt_clock_t time, rt_clock_t duration);
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/**
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* \brief Execute the next real-time task and schedule the next task, if any
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*
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* This function is called by the architecture dependent
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* code to execute and schedule the next real-time task.
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*
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*/
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void rt_task_run(void);
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/**
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* \brief Get the current clock time
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* \return The current time
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*
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* This function returns what the real-time module thinks
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* is the current time. The current time is used to set
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* the timeouts for real-time tasks.
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*
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* \hideinitializer
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*/
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#define RT_NOW() rt_arch_now()
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/**
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* \brief Get the time that a task last was executed
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* \param task The task
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* \return The time that a task last was executed
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*
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* This function returns the time that the task was last
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* executed. This typically is used to get a periodic
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* execution of a task without clock drift.
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*
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* \hideinitializer
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*/
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#define RT_TASK_TIME(task) ((task)->time)
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void rt_arch_init(void);
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void rt_arch_schedule(rt_clock_t t);
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rt_clock_t rt_arch_now(void);
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#include "rt-arch.h"
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#endif /* __RT_H__ */
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/** @} */
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