private string LookupStringTable(ushort identifier)
{
StringTable strTable = GetStringTableByIdentifier(identifier);
identifier -= strTable.identifierOffset;
IntPtr indexerTable = reader.ReadAddress32(strTable.indexTable, AddressingMode.Relative);
if (indexerTable == IntPtr.Zero)
{
return(null);
}
IntPtr addressTable = reader.ReadAddress32(strTable.addressTable, AddressingMode.Relative);
if (addressTable == IntPtr.Zero)
{
return(null);
}
/*
* Info by [qhris].
*
* Unicode strings are stored contiguous in a big buffer. To access this buffer
* the address table is used. The address table maps an address index to a string
* in the contiguous buffer.
*
* Note that all strings end with a null terminator and string length does not seem to
* be stored anywhere.
*
* To get the address index, the string identifier (unsigned short) is looked up in the
* item info table, along with a few checks to validate.
*/
var tableInfo = reader.Read <D2StringTableInfo>(indexerTable);
// We use the identifier 0x1F4 for invalid identifiers.
// because this is also what happens in D2Lang.dll
if (identifier >= tableInfo.IdentifierCount)
{
identifier = 0x01F4;
}
// Right after the string info table (in memory) lies the identifier -> address index
// mapping array.
IntPtr stringDataRegion = indexerTable + Marshal.SizeOf <D2StringTableInfo>();
Func <ushort, IntPtr> GetAddressIndexLocation = (index) => stringDataRegion + index * sizeof(ushort);
// Read address index; must be in valid range.
ushort addressTableIndex = reader.ReadUInt16(GetAddressIndexLocation(identifier));
if (addressTableIndex >= tableInfo.AddressTableSize)
{
return(null);
}
// Get the address containing string information.
IntPtr stringInfoBlock = GetAddressIndexLocation(tableInfo.IdentifierCount);
IntPtr stringInfoAddress = stringInfoBlock + addressTableIndex * Marshal.SizeOf <D2StringInfo>();
// Make sure it's in range.
IntPtr endTest = indexerTable + tableInfo.DataBlockSize;
if ((long)stringInfoAddress >= (long)endTest)
{
return(null);
}
// Check if the string has been loaded into the address table.
D2StringInfo stringInfo = reader.Read <D2StringInfo>(stringInfoAddress);
if (!stringInfo.IsLoadedUnicode)
{
return(null);
}
// If we get a null string address, just ignore it.
IntPtr stringAddress = reader.ReadAddress32(addressTable + addressTableIndex * sizeof(uint));
if (stringAddress == IntPtr.Zero)
{
return(null);
}
// A maximum of 0x4000 sized buffer **should** be enough to read all strings, bump if too low.
return(reader.GetNullTerminatedString(stringAddress, 0x100, 0x4000, Encoding.Unicode, AddressingMode.Absolute));
}