I'm using this file for notes to developers.


-----------------------------------
Programs to help you test your code
-----------------------------------


Cppcheck
	Cppcheck is a program that will run a static analysis of the code
	report likely errors.  I used the command:
	cppcheck --enable=all src/*.cpp > cppcheck_output.txt 2>&1

Valgrind
	Valgrind is an program that tracks memory usage.  So, if you
	forget to free memory or use memory after it has been freed,
	it will print out a warning.  To run Par2 with Valgrind, you
	the command is:
	valgrind --leak-check=yes par2 create foo.par2 input1.txt input2.txt

	The tests will run with Valgrind if you set the environment
	variable "VALGRINDOPTS".  That environment variable is put
	on the commandline after "valgrind".  So, I use:
	export PARVALGRINDOPTS="--leak-check=yes"

MinGW/WINE
	If you are on a UNIX box and want to check the Windows code,
	you can compile using MinGW and run using WINE.  MinGW is a
	package for compiling with GCC against Windows libraries.
	WINE is a Windows simulator.

	To compile with MinGW, I use the commands:
	make clean
	./configure --host=x86_64-w64-mingw32
	make

	To run Par2 with WINE, you need to tell it where
	MinGW's copy of the DLLs are.  Start by trying to
	run WINE by putting "wine" in front of your
	par.exe command:
	wine ./par2.exe create foo.par2 input1.txt input2.txt
	If you get a warning about "libgomp.dll" or any other
	DLL, use this command:
	x86_64-w64-mingw32-g++ --print-file-name=libgomp.dll
	which will tell you where to find MinGW's libgomp.dll.
	You then convert that Linux path to WINE's Windows path
	by running the command:
	winepath <directory_with_DLLs>
	On my machine, it just adds "z:" in front of the Linux
	path.  You tell WINE about all the DLL directories by
	putting those paths into the environment variable
	WINEPATH, separated by semi-colons.  I use:
	export WINEPATH="z:/usr/lib/gcc/x86_64-w64-mingw32/7.3-win32/;z:/usr/x86_64-w64-mingw32/lib/"
	Then, you should be able to run "wine par2.exe --help"
	to test that it works.

	If WINE is working, you can run tests in WINE with
	the command:
	make check

	WARNING: If the tests see that par2 or the unit tests have
	an ".exe" extension, they will be automatically run with
	WINE.  When switching from MinGW to normal GCC, you need
	to run "make clean" or the tests may run the wrong version
	(or run both versions).



-----------------------------------------
Below are some older notes about the code
-----------------------------------------


commandline.h / commandline.cpp

	class CommandLine;

	This class is used to process the command line arguments passed to
	par2cmdline. Basic verification is done to ensure that invalid
	combinations of options are not used and that files exist.

crc.h / crc.cpp

	u32 CRCUpdateChar(u32 crc, u8 ch);
	u32 CRCUpdateBlock(u32 crc, size_t length, const void *buffer);
	u32 CRCUpdateBlock(u32 crc, size_t length);

	void GenerateWindowTable(u64 window, u32 (&windowtable)[256]);
	u32 ComputeWindowMask(u64 window);
	u32 CRCSlideChar(u32 crc, u8 chNew, u8 chOld,
	                 const u32 (&windowtable)[256]);

	These functions are used to calculate and verify the CCITT CRC32 values
	for blocks of data in data files.

	The latter three functions allow the rapid computation of the crc for
	data in a sliding window.

creatorpacket.h / creatorpacket.cpp

	class CreatorPacket;

	This class is used to read and write "Creator Packets" to a recovery file.

criticalpacket.h / criticalpacket.cpp

	class CriticalPacket;
	class CriticalPacketEntry;

	CriticalPacket is the base class for DesriptionPacket, VerificationPacket,
	MainPacket, and CreatorPacket. CriticalPacket encapsulates memory
	allocation for the packet, computation of the packet hash and writing the
	packet to disk.

	CriticalPacketEntry is used to record that a copy of a specific critical
	packet will be written to a particular file at a specific offset.

datablock.h / datablock.cpp

	class DataBlock;

	Objects of this type are used to track blocks of data that belong to
	different files. When data is read from or written to a datablock, it
	calculates the correct file offset and length to use.

descriptionpacket.h / descriptionpacket.cpp

	class DescriptionPacket;

	This class is used to read and write "File Description Packets" to a
	recovery file. The class can compute the file id for the file when
	creating recovery files and will verify that the packet is ok when
	it is loaded from a recovery file.

diskfile.h / diskfile.cpp

	class DiskFile;
	class DiskFileMap;

	The DiskFile class encapsulates all file access. Each object of this type
	represents on file that par2cmdline is using, and references to it
	are used in any other object that needs to refer to a file.

	The DiskFileMap class is used to track which files have been processed.

filechecksummer.h / filechecksummer.cpp

	class FileCheckSummer;

	The FileCheckSummer is used to compute the CRC and HASH of a sliding
	window onto a data file. The CRC is updated continuously as the window
	is slid allong the file, and the HASH is only calculated when it
	is needed.

galois.h / galois.cpp

	class Galois;

	class GaloisTable;
	class GaloisLongMultiplyTable;

	The Galois object is used for galois arithmetic.

	GaloisTable encapsulates the log and antilog tables used for fast
	multiplation and division, and GaloisLongMultiplyTable is used by the
	ReedSolomon object to allow rapid multiplication of a block of data
	by the same value.

mainpacket.h / mainpacket.cpp

	class MainPacket;

	The MainPacket is used to read and write a "Main Packet" to and from
	a recovery file.

md5.h / md5.cpp

	class MD5Hash;
	class MD5Context;

	MD5Context objects are used to calculate the hash of a block of data.
	The resulting hash value is then stored in an MD5Hash object.

par2cmdline.h / par2cmdline.cpp

	int main(int argc, char *argv[]);

	par2cmdline.cpp defines the main() function which is responsible for
	creating a CommandLine object to parse the command line parameters, and
	then to create either a Par2Creator or a Par2Repairer to either
	create recovery files or use them to verify and repair data files.

	par2cmdline.h contains #include lines for all required header files,
	as well as a number of type definitions.

par2creator.h / par2creator.cpp

	class Par2Creator;

	This class encapsulates all of the procedures required to create recovery
	files from a set of data files.

par2creatorsourcefile.h / par2creatorsourcefile.cpp

	class Par2CreatorSourceFile;

	Each object of this type represent one of the data files for which
	recovery files are to be created. It handles creation of a
	DescriptionPacket and a VerificationPacket, computation of the full
	file hash and 16k hash values and the calculation and recording
	of the crc and hash values for each data block withint the file.

par2fileformat.h / par2fileformat.cpp

	struct PACKET_HEADER;
	struct FILEVERIFICATIONPACKET;
	struct FILEDESCRIPTIONPACKET;
	struct MAINPACKET;
	struct CREATORPACKET;
	struct RECOVERYBLOCKPACKET;

	These structures define the exact format used to store the various
	packets in a recovery file.

par2repairer.h / par2repairer.cpp

	class Par2Repairer;

	This class encapsulates all of the procedures required to use a set
	of recovery files to verify and repair the data files for which they
	were created.

par2repairersourcefile.h / par2repairersourcefile.cpp

	class Par2RepairerSourceFile;

	Each object of this class represents one of the data files that is
	being verified and repaired. It has a copy of the description packet
	and verification packet from the recovery files, and keeps track of
	exactly which disk files contain data blocks that belong to it.

recoverypacket.h / recoverypacket.cpp

	class RecoveryPacket;

	This class is used to read and write the header of a Recovery Packet.

	If contains a DataBlock object which is used to read and write data
	to or from the rest of the recovery packet.

verificationhashtable.h / verificationhashtable.cpp

	class VerificationHashTable;
	class VerificationHashEntry;

	The VerificationHashTable is to store details obtained from all of
	the verification packets. It is used to check whether or not the
	crc and hash values calculated by the FileCheckSummer match any of
	the data blocks from the data files.

verificationpacket.h / verificationpacket.cpp

	class VerificationPacket;

	This class is used to read a write Verification Packets to and from
	recovery files.

letype.h

	class leu32;
	class leu64;

	These two types are used by fileformat.h and are used to handle the
	type conversion between little endian and big endian numerical
	formats.