[2005] Reading bits in Big Endian format.

I made the following function that reads a specified number of bits from my internal buffer and returns the value

vb.net Code:

''' <summary>
        ''' Reads an unsigned value from the buffer.
        ''' </summary>
        ''' <param name="index">The index to start reading.</param>
        ''' <param name="length">The number of bits to read.</param>
        ''' <param name="OutputTo">When this method returns, contains the unsigned value read.</param>
        ''' <returns>An unsigned value read from the buffer.</returns>
        ''' <exception cref="ArgumentException">This method cannot read more than 64 bits.</exception>
        ''' <exception cref="ArgumentException">The value to be read extends past the end of the buffer.</exception>
 
        Public Shared Function unsigned(ByVal index As Int32, ByVal length As Int32, Optional ByRef OutputTo As Long = 0) As Long
            If length > 64 Then
                Throw New ArgumentException("length cannot be greater than 64")
                Exit Function
            End If
 
            If index + (length * 8) > OdwinBuffer.Length Then
                Throw New ArgumentException("end of buffer reached")
                Exit Function
            End If
 
            Dim num As Integer = 0
            Dim total As Integer = 0
 
            Do
                If GetBitflagState(index, CInt(Math.Ceiling(length / 8)), num) Then
                    total = total Or (1 << num)
                End If
                num += 1
            Loop While num < length
 
            OutputTo = total
            Return OutputTo
        End Function

GetBitflagState is a custom function that determines if a bit is set or not.

I know that big endian just reverses the bytes and it would be easy enough to read it like that but I need to read the bits. I have never worked with big endian before.

any help is great. thanks, troy.