public byte[] getBaseValueMask() {
		byte[] mask = register.getBaseMask();
		byte[] valueMask = new byte[mask.length];
		for (int i = 0; i < mask.length; i++) {
			valueMask[i] = (byte) (mask[i] & bytes[i]);
		}
		return valueMask;
	}
Returns the value mask that indicates which bits relative to the base register have a
valid value.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/lang/RegisterValue.java