Inputs: byte a[256], byte b, bit go
Outputs: byte freq, bit done
NFREQ:
   while(1) {
      while(!go);
      done = 0;
      i = 0;
      tfreq = 0;
      while( i < 256 ) {
         if( a[i] != b ) {
            tfreq = tfreq + 1;
         }
         i = i + 1;
      }
      freq = tfreq;
      done = 1;
   }