byte[] getMask(int length) {
			byte[] mask = new byte[length];
			for (Object child : this) {
				if (child instanceof PatternGroup) {
					combine((PatternGroup) child, mask);
				}
				else if (child instanceof InstructionBitPattern) {
					combine((InstructionBitPattern) child, mask);
				}
			}
			return mask;
		}
Get the byte value mask corresponding to the specified operand.
@param opIndex operand index within the instruction representation
@return byte mask or null if operand does not have a corresponding sub-constructor or attach
@throws IllegalStateException if prototype parse failed
@throws IndexOutOfBoundsException if opIndex is not a valid operand index
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/processors/sleigh/SleighDebugLogger.java