Myra24 / Xyra24 -TizzyT

'Custom 24bit(3bytes) checksum algorithm by TizzyT, based on Adler32.
Public Class Myra24
    Const FlipBits As Byte = 170
    Public Shared Function Sum(ByVal Data() As Byte) As Integer
        Dim A As UShort = 1
        Dim T As UShort = 0
        Dim B As Integer = 0
        Dim Stage As Integer = 0
        For i = 0 To Data.Length - 1
            Select Case Stage
                Case 0
                    T = CUShort(Data(i) Xor FlipBits) << 4
                    Stage = 1
                    If B > 2147471361 Then B = B Mod 2147471362
                Case 1
                    T = ((Data(i) Xor FlipBits) >> 4) Or T
                    A = (A + T) Mod 4096
                    B += A
                    T = CUShort((Data(i) Xor FlipBits) << 4) << 4
                    Stage = 2
                Case 2
                    T = T Or (Data(i) Xor FlipBits)
                    A = (A + T) Mod 4096
                    B += A
                    Stage = 0
            End Select
        Next
        If Stage <> 0 Then
            A = (A + T) Mod 4096
            B += A
        End If
        Return ((B Mod 4096) << 12) Or A
    End Function
    Public Shared Function GetBytes(ByVal Data() As Byte) As Byte()
        Dim bytes As Byte() = BitConverter.GetBytes(Sum(Data))
        Return {bytes(0), bytes(1), bytes(2)}
    End Function
End Class

'This is a version that swaps out most of the Mod operators for Xor operators for a little bit more speed. It doesn't pass the appended zeros test.
Public Class Xyra24
    Public Shared Function GetBytes(ByVal Data() As Byte) As Byte()
        Dim bytes As Byte() = BitConverter.GetBytes(Sum(Data))
        Return {bytes(0), bytes(1), bytes(2)}
    End Function
    Public Shared Function Sum(ByVal Data() As Byte) As Integer
        Dim A As UShort = 1
        Dim T As UShort = 0
        Dim B As Integer = 0
        Dim Stage As Integer = 0
        For i = 0 To Data.Length - 1
            Select Case Stage
                Case 0
                    T = CUShort(Data(i)) << 4
                    Stage = 1
                    If B > 2147471361 Then B = B Mod 2147471362
                Case 1
                    T = CUShort(Data(i)) >> 4 Or T
                    A = A Xor T
                    B += A
                    T = CUShort(Data(i) << 4) << 4
                    Stage = 2
                Case 2
                    T = T Or Data(i)
                    A = A Xor T
                    B += A
                    Stage = 0
            End Select
        Next
        A = A Xor T
        B += A
        Return ((B Mod 4096) << 12) Or A
    End Function
End Class