base/arch/i386/calibration/calibration_helper.c

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/*
 * Copyright (C) 2003 Paolo Mantegazza <mantegazza@aero.polimi.it>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.

 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sched.h>
#include <sys/mman.h>

#include <rtai_fifos.h>

int main(int argc, char *argv[])
{
    int fifo, period, skip, average = 0;
    char nm[RTF_NAMELEN+1];
    RT_TASK *task;
    RTIME expected;

        if ((fifo = open(rtf_getfifobyminor(0,nm,sizeof(nm)), O_WRONLY)) < 0) {
                printf("Error opening %s in calibration helper\n",nm);
                exit(1);
        }
    if (!(task = rt_task_init_schmod(nam2num("UCAL"), 0, 0, 0, SCHED_FIFO, 0xF))) {
        printf("Cannot init calibration helper\n");
        exit(1);
    }

    rt_set_oneshot_mode();
    period = start_rt_timer(nano2count(atoi(argv[1])));
    mlockall(MCL_CURRENT | MCL_FUTURE);
    rt_make_hard_real_time();
    expected = rt_get_time() + 100*period;
    rt_task_make_periodic(task, expected, period);
    for (skip = 0; skip < atoi(argv[2]); skip++) {
        expected += period;
        rt_task_wait_period();
        average += (int)count2nano(rt_get_time() - expected);
    }
    rt_make_soft_real_time();
    stop_rt_timer();    
    rt_task_delete(task);
    write(fifo, &average, sizeof(average));
    close(fifo);
    exit(0);
}

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