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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
/*
shmemtask.c
Set up a periodic task that increments a heartbeat in shared memory.
*/
#include "rtapi.h"
#include "rtapi_app.h" /* rtapi_app_main,exit() */
#include "common.h" /* shmem structure, SHMEM_KEY */
static int module;
static int shmem_task; /* the task ID */
static int shmem_mem; /* the shared memory ID */
enum { TIMER_PERIOD_NSEC = 1000000 }; /* timer period, in nanoseconds */
enum { SHMEM_PERIOD_NSEC = 1000000 }; /* task period, in nanoseconds */
enum { SHMEM_STACKSIZE = 1024 }; /* how big the stack is */
static int key = SHMEM_KEY;
static SHMEM_STRUCT *shmem_struct = 0;
/* task code, executed periodically */
void shmem_code(void *arg)
{
while (1) {
if (0 != shmem_struct) {
shmem_struct->heartbeat++;
}
rtapi_wait();
}
return;
}
/* part of the Linux kernel module that kicks off the shmem task */
int rtapi_app_main(void)
{
int retval;
int shmem_prio;
long period;
module = rtapi_init("SHMEMTASK");
if (module < 0) {
rtapi_print("shmemtask init: rtapi_init returned %d\n", module);
return -1;
}
/* allocate and initialize the shared memory structure */
shmem_mem = rtapi_shmem_new(key, module, sizeof(SHMEM_STRUCT));
if (shmem_mem < 0) {
rtapi_print("shmemtask init: rtapi_shmem_new returned %d\n",
shmem_mem);
rtapi_exit(module);
return -1;
}
retval = rtapi_shmem_getptr(shmem_mem, (void **) &shmem_struct);
if (retval < 0) {
rtapi_print("shmemtask init: rtapi_shmem_getptr returned %d\n",
retval);
rtapi_exit(module);
return -1;
}
shmem_struct->heartbeat = 0;
/* is timer started? if so, what period? */
period = rtapi_clock_set_period(0);
if (period == 0) {
/* not running, start it */
rtapi_print("shmemtask init: starting timer with period %ld\n",
TIMER_PERIOD_NSEC);
period = rtapi_clock_set_period(TIMER_PERIOD_NSEC);
if (period < 0) {
rtapi_print
("shmemtask 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("shmemtask init: clock period too long: %ld\n", period);
rtapi_exit(module);
return -1;
}
rtapi_print("shmemtask init: desired clock %ld, actual %ld\n",
TIMER_PERIOD_NSEC, period);
/* set the task priority to lowest, since we only have one task */
shmem_prio = rtapi_prio_lowest();
/* create the shmem task */
shmem_task = rtapi_task_new(shmem_code, 0 /* arg */ , shmem_prio, module,
SHMEM_STACKSIZE, RTAPI_NO_FP);
if (shmem_task < 0) {
rtapi_print("shmemtask init: rtapi_task_new returned %d\n",
shmem_task);
rtapi_exit(module);
return -1;
}
/* start the shmem task */
retval = rtapi_task_start(shmem_task, SHMEM_PERIOD_NSEC);
if (retval < 0) {
rtapi_print("shmemtask init: rtapi_task_start returned %d\n", retval);
rtapi_exit(module);
return -1;
}
rtapi_print("shmemtask init: started shmem task\n");
return 0;
}
/* part of the Linux kernel module that stops the shmem task */
void rtapi_app_exit(void)
{
int retval;
if (0 != shmem_struct) {
rtapi_print("shmemtask exit: heartbeat is %u\n",
shmem_struct->heartbeat);
}
retval = rtapi_task_pause(shmem_task);
if (retval < 0) {
rtapi_print("shmemtask exit: rtapi_task_stop returned %d\n", retval);
}
retval = rtapi_task_delete(shmem_task);
if (retval < 0) {
rtapi_print("shmemtask exit: rtapi_task_delete returned %d\n",
retval);
}
retval = rtapi_shmem_delete(shmem_mem, module);
if (retval < 0) {
rtapi_print("shmemtask exit: rtapi_shmem_delete returned %d\n",
retval);
}
/* Clean up and exit */
rtapi_exit(module);
}
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