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// Copyright 2003 John Kasunich
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
/*
master.c
Set up a periodic task that gives a semaphore every several
task cycles. Load this first, since it defines 'master_sem',
the global referenced by slave task.
*/
#include "rtapi.h"
#include "rtapi_app.h" /* rtapi_app_main,exit() */
#include "common.h" /* semaphore key */
static int module;
static int master_sem; /* the semaphore ID */
static int master_task; /* the task ID */
static unsigned int master_count = 0;
enum { TIMER_PERIOD_NSEC = 10000000 }; /* timer period, in nanoseconds */
enum { MASTER_PERIOD_NSEC = 1000000000 }; /* timer period, in
nanoseconds */
enum { MASTER_STACKSIZE = 1024 }; /* how big the stack is */
/* task code, executed each timer interrupt */
void master_code(void *arg)
{
while (1) {
rtapi_print("master: giving semaphore, count = %d\n", master_count);
rtapi_sem_give(master_sem);
rtapi_print("master: gave semaphore, count = %d\n", master_count);
master_count++;
rtapi_wait();
}
return;
}
/* part of the Linux kernel module that kicks off the timer task */
int rtapi_app_main(void)
{
int retval;
int master_prio;
long period;
module = rtapi_init("SEM_MASTER");
if (module < 0) {
rtapi_print("sem master init: rtapi_init returned %d\n", module);
return -1;
}
/* create the semaphore */
master_sem = rtapi_sem_new(SEM_KEY, module);
if (master_sem < 0) {
rtapi_print("sem master init: rtapi_sem_new returned %d\n",
master_sem);
rtapi_exit(module);
return -1;
}
/* is timer started? if so, what period? */
period = rtapi_clock_set_period(0);
if (period == 0) {
/* not running, start it */
rtapi_print("sem master init: starting timer with period %ld\n",
TIMER_PERIOD_NSEC);
period = rtapi_clock_set_period(TIMER_PERIOD_NSEC);
if (period < 0) {
rtapi_print
("sem master init: rtapi_clock_set_period failed with %ld\n",
period);
rtapi_exit(module);
return -1;
}
}
/* make sure period <= desired period (allow 1% roundoff error) */
if (period > (TIMER_PERIOD_NSEC + (TIMER_PERIOD_NSEC / 100))) {
/* timer period too long */
rtapi_print("sem master init: clock period too long: %ld\n", period);
rtapi_exit(module);
return -1;
}
rtapi_print("sem master init: desired clock %ld, actual %ld\n",
TIMER_PERIOD_NSEC, period);
/* set the task priority to one above the lowest; the slave task will be
the lowest */
master_prio = rtapi_prio_next_higher(rtapi_prio_lowest());
/* create the master task */
master_task =
rtapi_task_new(master_code, 0 /* arg */ , master_prio, module,
MASTER_STACKSIZE, RTAPI_NO_FP);
if (master_task < 0) {
rtapi_print("sem master init: rtapi_task_new returned %d\n",
master_task);
rtapi_exit(module);
return -1;
}
/* start the master task */
retval = rtapi_task_start(master_task, MASTER_PERIOD_NSEC);
if (retval < 0) {
rtapi_print("sem master init: rtapi_task_start returned %d\n",
retval);
rtapi_exit(module);
return -1;
}
rtapi_print("sem master init: started master task\n");
return 0;
}
/* part of the Linux kernel module that stops the master task */
void rtapi_app_exit(void)
{
int retval;
retval = rtapi_task_pause(master_task);
if (retval < 0) {
rtapi_print("sem master exit: rtapi_task_stop returned %d\n", retval);
}
retval = rtapi_task_delete(master_task);
if (retval < 0) {
rtapi_print("sem master exit: rtapi_task_delete returned %d\n",
retval);
}
retval = rtapi_sem_delete(master_sem, module);
if (retval < 0) {
rtapi_print("sem master exit: rtapi_sem_delete returned %d\n",
retval);
}
rtapi_print("sem master exit: master count is %d\n", master_count);
rtapi_exit(module);
}
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