public static uint HashFilename(string name, PackageHashType type)
{
switch (type)
{
case PackageHashType.Classic:
{
name = name.ToUpperInvariant();
if (name.Length % 4 != 0)
name = name.PadRight(name.Length + (4 - name.Length % 4), '\0');
using (var ms = new MemoryStream(Encoding.ASCII.GetBytes(name)))
{
var len = name.Length >> 2;
uint result = 0;
while (len-- != 0)
result = ((result << 1) | (result >> 31)) + ms.ReadUInt32();
return result;
}
}
case PackageHashType.CRC32:
{
name = name.ToUpperInvariant();
var l = name.Length;
var a = l >> 2;
if ((l & 3) != 0)
{
name += (char)(l - (a << 2));
var i = 3 - (l & 3);
while (i-- != 0)
name += name[a << 2];
}
return CRC32.Calculate(Encoding.ASCII.GetBytes(name));
}
default: throw new NotImplementedException("Unknown hash type `{0}`".F(type));
}
}