hi,

No time to look at code deeply, but in short, I think you confused with logical operations. Use direct load when it is possible. Look here:

		if(nine) {	// receive HHHHLLLL
			high |= (a&0xF0) >> 4;	// high: 0000HHHH  <- replace with high = (a&0xF0) >> 4;
			low |= (a&0x0F) << 4;	// low: LLLLXXXX <- replace with low = (a&0x0F) << 4;

Next:

		else if(flag) {	// receive LLLLHHHH
			low = (a&0xF0) >> 4;	// low = LLLLLLLL <- replace with low |= (a&0xF0) >> 4;
//...
			high |= a&0x0F;	// high: 0000HHHH <- replace with high = a&0x0F;

Finally:

		else {	// receive LLLLLLLL
			low |= a;	// low: LLLLLLLL <- replace with low = a;

Regards,
Oleg