Alhexx' ObsCure HVP File Format Description V1.00
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Here we go, another format description.
This time we're analysing ObsCure's HVP format.


IMPORTANT NOTE:
All integers in this file format are BIG ENDIAN !!!
(i.e. Motorola Order)
There's one exception: HVP_MAIN_ENTRY.ulStructType
is in LITTLE ENDIAN order.


First, I have to say that I haven't fully decoded this
format, but I have enough info to at least decompress
the files.



Let's start with the structures:

Header
------
struct HVP_HEADER
{
	char		szId[12];	// "HV PackFile\0"
	unsigned long	ulVersion;	// 0x01000300
	unsigned long	ulNumRootDirs;	// Directories in Root
	unsigned long	ulNumEntries;	// Files + Directories
	unsigned long	ulNumFiles;
	unsigned long	ulTOCSize;	// 
	unsigned long	ulUnknown5;	// ???
	unsigned long	ulUnknown6;	// ???
}; // 40 Bytes

Main Entry
----------
struct HVP_MAIN_ENTRY
{
	unsigned long	ulStructSize;	// 
	unsigned long	ulStructType;	// io: 0 = directory, 1 = file
}; // 8 Bytes

Dir Entry
---------
struct HVP_DIR_ENTRY
{
	unsigned char	ucUnknown;	// 0
	unsigned long	ulSubFiles;
	unsigned long	ulNameLength;	
	char		szName[ulNameLength];
}; // 9 + x Bytes

File Entry
----------
struct HVP_FILE_ENTRY
{
	unsigned char	ucUnknown;	// 1
	unsigned long	ulPackedSize;
	unsigned long	ulRealSize;
	unsigned long	ulUnknown3;
	unsigned long	ulOffset;
	unsigned long	ulNameLength;
	char		szName[ulNameLength];
}; // 21 + x Bytes




The Entries: Dir Entry VS File Entry
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In this format, both file and dir entries are mixed.
After you have read the header, read a 
HVP_MAIN_ENTRY struct.
Then, check the HVP_MAIN_ENTRY.ulStructType member.
If it is 0, then a HVP_DIR_ENTRY follows.
If it is 1, then a HVP_FILE_ENTRY follows.
Quite simple, huh?


Note:
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Usually, when you read out a HVP_FILE_ENTRY struct, then the
ucUnknown member is 1.
However, I had problems when trying to load the archive "datapack.hvp".

After deactivating the check, that means after ignoring
the ucUnknown member, my decompressor was able to load the archive.



Compression:
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As you can see in the HVP_FILE_ENTRY struct, there's a member called
ulPackedSize. If ulPackedSize is smaller that ulRealSize, then the
file data is compressed using default ZIP compression.
If ulPackedSize is equal to ulRealSize, then the file is uncompressed.


That's all for now.

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 - Alhexx
01:59 2006-02-22