private void determineCvSigValues() throws CancelledException, IOException, PdbException {
		PdbDebugInfo debugInfo = pdb.getDebugInfo();
		if (debugInfo == null) {
			return;
		}
		if (debugInfo.getModuleInformationList().isEmpty()) {
			return;
		}
		// We are assuming that first in the list is the one to look at for cases 1 and 2.
		//  If something else like lowest stream number, then need to change the logic.
		ModuleInformation moduleInfo = debugInfo.getModuleInformationList().get(0);
		int streamNumber = moduleInfo.getStreamNumberDebugInformation();
		if (streamNumber == MsfStream.NIL_STREAM_NUMBER) {
			return;
		}
		PdbByteReader reader = pdb.getReaderForStreamNumber(streamNumber);
		// Skipping pulling out of sub-reader for symbols, as symbols stuff is first.
		if (getSig) {
			cvSignature = reader.parseInt();
		}
		switch (cvSignature) {
			case 1:
			case 2:
				// We have no 1,2 examples to test this logic for cvSignature.  Confirming
				// or rejecting this logic is important for simplifying/refactoring this
				// method or writing new methods to allow for extraction of information from
				// individual modules.  The current implementation has cross-module logic
				// (setting state in the processing of the first and using this state in the
				// processing of follow-on modules).
				getSig = false;
				break;
			case 4:
				break;
			default:
				if (cvSignature < 0x10000) {
					throw new PdbException(
						"Invalid module CV signature in stream " + streamNumber);
				}
				break;
		}
		cvSignatureCase1and2Stream = streamNumber;
	}
Deserializes and initializes basic {@link SymbolRecords} information from the stream noted
in the DBI header so that later symbol queries can be done
@throws IOException on file seek or read, invalid parameters, bad file configuration, or
 inability to read required bytes
@throws PdbException upon not enough data left to parse
@throws CancelledException upon user cancellation
Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb2/pdbreader/SymbolRecords.java