public BigInteger parseUnsignedLongVal() throws PdbException {
		checkLimit(8);
		byte[] selectedBytes = Arrays.copyOfRange(bytes, index, index + 8);
		selectedBytes = Arrays.copyOf(selectedBytes, 8);
		index += 8;
		return LittleEndianDataConverter.INSTANCE.getBigInteger(selectedBytes, 8, false);
	}
Parses an (64-bit) unsigned long from the PdbByteReader and returns its positive
 BigInteger value.
@return The positive long value of the parsed unsigned int.
@throws PdbException Upon not enough data left to parse.
Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb2/pdbreader/PdbByteReader.java