Optimizing byte array to string encoder

[Chris001]

Hi, below is a byte array to string encoder. It uses the yEnc algorithm that is used for Usenet binaries (Usenet only supports text).

Doing a performance analysis in VS2010 shows that this is the most CPU intensive part of the application.

The encoder function is used thousands of times, so I'd like to optimize it as much as possible.
Does anybody know if more improvements can be made?

I'm using 'ReDim Preserve' instead of 'Take()ToArray', because I'm targeting .NET Framework 2.0. Is there a more efficient way of getting only a part of a byte array?

'Values for yEnc Encoder
Public Structure EncoderValues
    Public lChar As Byte
    Public IsSingleChar As Boolean
    Public CheckLine0 As Boolean
    Public Line0Char As Byte
End Structure
Public m_EncoderTable(255) As EncoderValues
 
'This is called in the Form_Load event.
Public Sub SetupEncoder()
    Dim lngInput As Integer, bTest As Byte
    For lngInput = 0 To 255
        With m_EncoderTable(lngInput)
            bTest = CByte((lngInput + 42) Mod 256)
            Select Case bTest
                Case 1 To 8, 11 To 12, 14 To 45, 47 To 60, 62 To 255    'Normal processing
                    .lChar = bTest
                    .IsSingleChar = True
                Case 46                                           'Test for column one, escape if in that col.
                    .lChar = bTest
                    .IsSingleChar = False
                    .CheckLine0 = True
                    .Line0Char = CByte((bTest + 64) Mod 256)
                Case Else                                         'Critical char, needs to be escaped.
                    .lChar = CByte((bTest + 64) Mod 256)
                    .IsSingleChar = False
            End Select
        End With
    Next lngInput
End Sub
 
 
Public Function EncodeData(ByVal bIn() As Byte) As String
 
    Dim bOut() As Byte, lChar As Integer, lPos As Integer, lLine As Integer
 
    ReDim bOut(UBound(bIn) * 2)             'Make the output buffer.  Double size will almost always be enough.  2 extra
    'chars per 72 and worst case would be all characters escaped.  If so, use Base64.
    For lChar = 0 To UBound(bIn)
        With m_EncoderTable(bIn(lChar))
            If .IsSingleChar Then             'Normal processing
                bOut(lPos) = .lChar
                lPos += 1
                lLine += 1
            ElseIf .CheckLine0 Then           'Test for column one, escape if in that col.
                If lLine <> 0 Then
                    bOut(lPos) = .lChar
                    lPos += 1
                    lLine += 1
                Else
                    bOut(lPos) = 61
                    bOut(lPos + 1) = .Line0Char
                    lPos += 2
                    lLine += 2
                End If
            Else                              'Critical char, needs to be escaped.
                bOut(lPos) = 61
                bOut(lPos + 1) = .lChar
                lPos += 2
                lLine += 2
            End If
        End With
        If lLine >= 128 Then           'Add a vbCrLf
            bOut(lPos) = 13
            bOut(lPos + 1) = 10
            lPos += 2
            lLine = 0
        End If
    Next lChar
 
    ReDim Preserve bOut(lPos - 1)           'Truncate the unused portion of the buffer.
    Return System.Text.Encoding.GetEncoding(1252).GetString(bOut)
End Function