#include <stdio.h>

int main(void) {
  unsigned short mask = 0xbc61;

  // convert to new mask 0xbcaa
  mask ^= 0xCB; // mask now is 0xbcaa
  printf("New mask %#x\n", mask);
  
  // convert back to 0xbc61
  mask ^= 0xCB; // mask now is 0xbc61
  printf("New mask %#x\n", mask);
  
  return 0;
}