/// <summary>
/// Create a OS9 module file object.
/// </summary>
/// <param name="fileinfo">Directory information for this file, or <value>null</value> if no directory information is available.</param>
/// <param name="filedata">Raw file data, including headers and payload.</param>
/// <param name="validate">If cleared, an invalid module file can be created, i.e. header and file checksum values are not validated.</param>
internal OS9ModuleFile(OS9FileInfo fileinfo, byte[] filedata, bool validate = true) : base(fileinfo)
{
if (filedata == null)
{
throw new ArgumentNullException("filedata");
}
var filename = fileinfo == null ? null : fileinfo.Name;
if (filedata.Length < StandardModuleHeaderSize)
{
throw new InvalidFileException(filename, String.Format("A module file must contain a {0} byte header. This file is only {1} bytes long.", StandardModuleHeaderSize, filedata.Length));
}
if (filedata[0] != 0x87 || filedata[1] != 0xcd)
{
throw new InvalidFileException(filename, "Module file header does not contain valid sync sequence.");
}
data = (byte[])filedata.Clone();
if (ModuleSize > data.Length)
{
throw new InvalidFileException(filename, String.Format("The module header specifies a module size of {0} bytes but the file is only {1} bytes.", ModuleSize, data.Length));
}
int nameoffset = (data[4] << 8) | data[5];
if (nameoffset > data.Length)
{
throw new InvalidFileException(filename, "Module filename offset is outside the file data.");
}
ModuleName = OS9Utils.ParseString(data, nameoffset);
if (validate)
{
if (HeaderParity != CalculateHeaderParity(data, StandardModuleHeaderSize - 1))
{
throw new InvalidFileException(filename, "Header parity error");
}
if (ModuleCRC != CalculateModuleCRC(data, ModuleSize - 3))
{
throw new InvalidFileException(filename, "Invalid module CRC");
}
}
}
