#include <intrins.h>

bit _testbit_ (
  bit b);      /* bit to test and clear */

The _testbit_ routine produces a JBC instruction in the generated program code to simultaneously test the bit b and clear it to 0. This routine may be used only on directly-addressable bit variables and is invalid on any type of expression. This routine is implemented as an intrinsic function.

The _testbit_ routine returns the value of b.

#include <intrins.h>
#include <stdio.h> /* for printf */

void tst_testbit (void){
  bit test_flag;

  if (_testbit_ (test_flag))
    printf ("Bit was set\n");
  else
    printf ("Bit was clear\n");
}