test1.c

QNX ver4.25 education example code

/******************************************************************************
 *  test1.c : show the rdtsc counter on a pentium class machine
 ******************************************************************************/
#ifdef __USAGE
%C [ -p priority ]

priority   = priority to run at (0 to 29) Default=10
e.g. 
%C -p 29
#endif
 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/kernel.h>
#include <sys/vc.h>
#include <sys/seginfo.h>
#include <sys/osinfo.h>
#include <sys/name.h>
#include <i86.h>
#include <sys/irqinfo.h>
#include <sys/proxy.h>
#include <sys/sched.h>
#include <sys/timers.h>
#include <sys/name.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <sys/trace.h>
#include <sys/tracecod.h>
#include <math.h>
#include <time.h>
#include <signal.h>

#include "64bit.h"

/* globals */

double   seconds_per_tick;
Long     start_time64, stop_time64;
int      priority = 10;

#define NANOS_PER_SEC    1000000000
#define MICROS_PER_SEC   1000000
#define MILLIS_PER_SEC   1000

#define HIGHEST_PRIORITY     29

set_my_priority( int priority ) {
	int ret;

    ret = setprio( getpid(), priority );
    if ( ret == -1 ) {
       fprintf(stderr,"Error setting priority. (%s)\n",strerror(errno));
       exit(-1);
       }
	return(ret);
	}

sync_pentium() {
	Long diff;
	double ticks_per_second;
	int previous_priority;

    // get synchronization values for this Pentium
	do {

        previous_priority = set_my_priority( HIGHEST_PRIORITY );
    	rdtsc64( &start_time64 );  // snap time
        sleep(1);
    	rdtsc64( &stop_time64 );   // snap time
        set_my_priority( previous_priority );

		} while (start_time64.lo > stop_time64.lo);

    _Lsub( &diff, stop_time64, start_time64 ); 

	ticks_per_second = (float)diff.lo;
    seconds_per_tick = 1.000000000 / ticks_per_second;

	printf( "\nPentium Clock Speed Measurement:\n\n" );
	printf( "1 second took %lf cycles on this machine.\n", ticks_per_second );
	printf( "Each cycle is %18.15lf seconds, or %8.3lf nanoseconds.\n",
              seconds_per_tick, seconds_per_tick * NANOS_PER_SEC );
	printf( "This is a %3.1f MHz Pentium.\n\n",
		(float) ticks_per_second / 1000000.0);
    }

main(int argc, char **argv) {
    int     c;

    while ( ( c = getopt( argc, argv, "p:" ) ) != -1 ) {
         switch(c) {
            case 'p' : priority = atoi(optarg);
                       if ( priority < 0 || priority > 29 ) {
                          fprintf(stderr,"Invalid priority. Defaulting to 10.\n");
                          priority = 10;
                          }
                       break;
            }
         }

    if ( setprio( getpid(), priority ) == -1 ) {
       fprintf(stderr,"Error setting priority. (%s)\n",strerror(errno));
       exit(-1);
       }

	sync_pentium();
    go();
	}


go() {
    Long diffl;
	double diffd;

    while (1) {              
   		rdtsc64( &start_time64 );  // snap time
		sleep(1);
   		rdtsc64( &stop_time64 );   // snap time

        _Lsub( &diffl, stop_time64, start_time64 ); 
        diffd = (float)diffl.lo * seconds_per_tick;

		printf("%12.9f\n", diffd);
		fflush(stdout);
		}
	}