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Initial code for a Contiki real-time scheduler

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adamdunkels 2007-03-19 00:16:13 +00:00
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commit 31a4d8504a
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core/sys/rt.c Normal file
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/*
* Copyright (c) 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.
*
* @(#)$Id: rt.c,v 1.1 2007/03/19 00:16:13 adamdunkels Exp $
*/
#include "sys/rt.h"
#include "contiki.h"
#define LIST_SIZE 16
static struct rt_task *tasks[LIST_SIZE];
static u8_t next, firstempty;
#define DEBUG 0
#if DEBUG
#include <stdio.h>
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
/*---------------------------------------------------------------------------*/
void
rt_init(void)
{
next = 0;
firstempty = 0;
rt_arch_init();
}
/*---------------------------------------------------------------------------*/
int
rt_post(struct rt_task *task, rt_clock_t time, rt_clock_t duration)
{
int i;
PRINTF("rt_post time %d\n", time);
/* Check if task queue is full. */
if(firstempty == (next - 1) % LIST_SIZE) {
PRINTF("rt_post: next %d firstempty %d full\n", next, firstempty);
return RT_ERR_FULL;
}
/* Check if it is possible to run this task at the requested
time. */
for(i = next; i != firstempty;
i = (i + 1) % LIST_SIZE) {
/* XXX: should check a range of time not just the same precise
moment. */
if(tasks[i]->time == time) {
PRINTF("rt_post: next %d firstempty %d time %d == %d\n",
next, firstempty, tasks[i]->time, time);
return RT_ERR_TIME;
}
}
/* Put the task at the end of the task list. */
task->time = time;
tasks[firstempty] = task;
PRINTF("rt_post: putting task %s as %d\n", task->name, firstempty);
firstempty = (firstempty + 1) % LIST_SIZE;
/* PRINTF("rt_post: next %d firstempty %d scheduling soon\n",
next, firstempty);*/
/* Check if this is the first task on the list. If so, we need to
run the rt_arch_schedule() function to get the ball rolling. */
if(firstempty == (next + 1) % LIST_SIZE) {
PRINTF("rt_post scheduling %d %s (%d)\n",
next, tasks[next]->name, tasks[next]->time);
rt_arch_schedule(time);
}
return RT_OK;
}
/*---------------------------------------------------------------------------*/
void
rt_task_run(void)
{
int i, n;
struct rt_task *t;
t = tasks[next];
/* Increase the pointer to the next task. */
next = (next + 1) % LIST_SIZE;
/* Run the task. */
PRINTF("rt_task_run running %s\n", t->name);
t->func(t, t->ptr);
if(next == firstempty) {
PRINTF("rt_task_run: empty task list\n");
/* The list is empty, no more tasks to schedule. */
return;
}
/* Find the next task to run. */
n = next;
for(i = next; i != firstempty; i = (i + 1) % LIST_SIZE) {
PRINTF("rt_task_run checking %s (%d) against %s (%d)\n",
tasks[i]->name, tasks[i]->time,
tasks[n]->name, tasks[n]->time);
if(tasks[i]->prio >= tasks[n]->prio &&
RT_CLOCK_LT(tasks[i]->time, tasks[n]->time)) {
n = i;
}
}
PRINTF("rt_task_run next task is %d %s (%d)\n",
n, tasks[n]->name, tasks[n]->time);
/* Put the next task first in the task list. */
t = tasks[next];
tasks[next] = tasks[n];
tasks[n] = t;
PRINTF("rt_task_run scheduling %d %s (%d)\n",
next, tasks[next]->name, tasks[next]->time);
rt_arch_schedule(tasks[next]->time);
}
/*---------------------------------------------------------------------------*/

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/**
* \defgroup rt Real-time task scheduling
*
* The real-time module handles the scheduling and execution of
* real-time tasks (with predictible execution times).
*
* @{
*/
/**
* \file
* Header file for the real-time module.
* \author
* Adam Dunkels <adam@sics.se>
*
*/
/*
* Copyright (c) 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.
*
* @(#)$Id: rt.h,v 1.1 2007/03/19 00:16:13 adamdunkels Exp $
*/
#ifndef __RT_H__
#define __RT_H__
typedef unsigned short rt_clock_t;
#define RT_CLOCK_LT(a,b) ((signed short)((a)-(b)) < 0)
/**
* \brief Initialize the real-time scheduler.
*
* This function initializes the real-time scheduler and
* must be called at boot-up, before any other functions
* from the real-time scheduler is called.
*/
void rt_init(void);
/**
* \brief Repressentation of a real-time task
*
* This structure represents a real-time task and is used
* by the real-time module and the architecture specific
* support module for the real-time module.
*/
struct rt_task {
char *name;
rt_clock_t time;
void (* func)(struct rt_task *t, void *ptr);
unsigned char prio;
void *ptr;
};
/**
* \brief Declare a real-time task.
* \param name The name of the task state variable.
* \param func The function implementing the real-time task.
* \param prio The priority of the task.
* \param ptr An opaque pointer that is passed to the real-time task
* when it is executed.
*
* This macro declares a real-time task.
*
* \hideinitializer
*/
#define RT_TASK(name, func, prio, ptr) { name, 0, func, prio, ptr }
enum {
RT_OK,
RT_ERR_FULL,
RT_ERR_TIME,
};
/**
* \brief Post a real-time task.
* \param task A pointer to the task variable previously declared with RT_TASK().
* \param time The time when the task is to be executed.
* \return Non-zero (true) if the task could be scheduled, zero
* (false) if the task could not be scheduled.
*
* This function schedules a real-time task a specified
* time in the future.
*
*/
int rt_post(struct rt_task *task, rt_clock_t time, rt_clock_t duration);
/**
* \brief Execute the next real-time task and schedule the next task, if any
*
* This function is called by the architecture dependent
* code to execute and schedule the next real-time task.
*
*/
void rt_task_run(void);
/**
* \brief Get the current clock time
* \return The current time
*
* This function returns what the real-time module thinks
* is the current time. The current time is used to set
* the timeouts for real-time tasks.
*
* \hideinitializer
*/
#define RT_NOW() rt_arch_now()
/**
* \brief Get the time that a task last was executed
* \param task The task
* \return The time that a task last was executed
*
* This function returns the time that the task was last
* executed. This typically is used to get a periodic
* execution of a task without clock drift.
*
* \hideinitializer
*/
#define RT_TASK_TIME(task) ((task)->time)
void rt_arch_init(void);
void rt_arch_schedule(rt_clock_t t);
rt_clock_t rt_arch_now(void);
#include "rt-arch.h"
#endif /* __RT_H__ */
/** @} */