case 3: if (BitStream[j]==1) return 0; break; //should be 0 spacer bit
case 2: if (BitStream[j]==0) return 0; break; //should be 1 spacer bit
default: //test parity
case 3: if (BitStream[j]==1) return 0; break; //should be 0 spacer bit
case 2: if (BitStream[j]==0) return 0; break; //should be 1 spacer bit
default: //test parity