#include <intrins.h>

int _prior_ (
  long value);    /* value to normalize */

The _priord_ routine uses the PRIOR instruction to count the number of shifts required to normalize value. The value returned is a number from 0 to 31 which indicates how many times value must be shifted left before the MSB is set.

The _priord_ function returns the number of shifts required to normalize value.

_prior_

#include <intrins.h>

void testprior (long val) {
  volatile int temp;

  temp = _priord_ (val);
}