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#include <sys/time.h>
#include <stdio.h>
// count to a billion. Time it. If it's < 1 sec, count to 10B, etc.
unsigned long micro = 1;
void myusec_delay(int time)
{
volatile unsigned long i;
for (i = 0; i < time * micro; i++)
;
}
void myusec_calibrate_delay()
{
int count = 1000;
unsigned long timeusec;
struct timeval start, end;
int ok = 0;
printf("Setting up microsecond timing loop\n");
while (!ok) {
gettimeofday(&start, 0);
myusec_delay(count);
gettimeofday(&end, 0);
timeusec = 1000000 * (end.tv_sec - start.tv_sec ) +
(end.tv_usec - start.tv_usec);
count *= 2;
if (timeusec < 1000000/4)
continue;
ok = 1;
}
// compute one microsecond. That will be count / time
micro = count / timeusec;
fprintf(stderr, "%ldM loops per second\n", (unsigned long)micro);
}
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