/********************************************************************
*
* Copyright 2010 by Sean Conner.  All Rights Reserved.
*
* 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.
*
* Comments, questions and criticisms can be sent to: sean@conman.org
*
* --------------------------------------------------------------------
*
* Used to test the resolution of nanosleep().  To compile:
*
* Linux:
*	gcc -std=c99 -Wall -Wextra -pedantic -g -o nanosleep nanosleep.c
*
* Solaris:
*	cc -xc99 -g -o nanosleep nanosleep.c -lrt
*
* To run:
*	./nanosleep
*	./nanosleep X # X = number of seconds to run program
*
************************************************************************/

#define _POSIX_C_SOURCE	200112L

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <stdbool.h>
#include <assert.h>

#include <sys/time.h>

#define DEFSECS	3

/*********************************************************************/

static int timevalcmp(
	const struct timeval *const restrict a,
	const struct timeval *const restrict b
)
{
  assert(a != NULL);
  assert(b != NULL);
    
  if (a->tv_sec < b->tv_sec)
    return -1;
  else if (a->tv_sec > b->tv_sec)
    return  1;

  if (a->tv_usec < b->tv_usec)
    return -1;
  else if (a->tv_usec > b->tv_usec)
    return  1;
  
  return 0;
}

/*********************************************************************/

int main(int argc,char *argv[])
{
  struct timespec interval;
  struct timeval  start;
  struct timeval  stop;
  unsigned long   count;
  unsigned long   secs;
  
  if (argc == 1)
    secs = DEFSECS;
  else
    secs = strtoul(argv[1],NULL,10);

  gettimeofday(&stop,NULL);  
  stop.tv_sec += secs;
  count = 0;
  
  while(true)
  {
    gettimeofday(&start,NULL);
    if (timevalcmp(&start,&stop) > 0) break;
    interval.tv_sec  = 0;
    interval.tv_nsec = 1000;
    nanosleep(&interval,NULL);
    count++;
  }
  
  printf("%lu %lu/sec\n",count,count / secs);
  return EXIT_SUCCESS;
}