Change Hex Number To Dec Number

Function hex_2_num(hexnum As String) As Variant
    Dim bogus As Boolean
    bogus = False
    For x = 1 To Len(hexnum)
        Select Case Mid$(hexnum, x, 1)
        Case Is = "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"
        Case Else
            bogus = True
        End Select
    Next x
    If Not bogus Then
        Dim hexes(5, 1) As String
        hexes(0, 0) = "A"
        hexes(0, 1) = "10"
        hexes(1, 0) = "B"
        hexes(1, 1) = "11"
        hexes(2, 0) = "C"
        hexes(2, 1) = "12"
        hexes(3, 0) = "D"
        hexes(3, 1) = "13"
        hexes(4, 0) = "E"
        hexes(4, 1) = "14"
        hexes(5, 0) = "F"
        hexes(5, 1) = "15"
        
        For x = Len(hexnum) To 1 Step -1
            Position = Len(hexnum) - x + 1
            If Position > 8 Then
                MsgBox "Number too large"
                'Call clearcontents
                Exit Function
            End If
            If IsNumeric(Mid$(hexnum, x, 1)) Then
                Select Case Position
                    Case Is = 1
                        Position = 1
                    Case Is = 2
                        Position = 16
                    Case Is = 3
                        Position = 256
                    Case Is = 4
                        Position = 4096
                    Case Is = 5
                        Position = 65536
                    Case Is = 6
                        Position = 1048576
                    Case Is = 7
                        Position = 16777216
                    Case Is = 8
                        Position = 268435456
                End Select
                returnvalue = returnvalue + (Position * CInt(Mid$(hexnum, x, 1)))
            Else
                For y = 0 To 5
                    If hexes(y, 0) = Mid$(hexnum, x, 1) Then
                           multiplier = hexes(y, 1)
                    End If
                Next y
                Select Case Position
                    Case Is = 1
                        Position = 1
                    Case Is = 2
                        Position = 16
                    Case Is = 3
                        Position = 256
                    Case Is = 4
                        Position = 4096
                    Case Is = 5
                        Position = 65536
                    Case Is = 6
                        Position = 1048576
                    Case Is = 7
                        Position = 16777216
                    Case Is = 8
                        Position = 268435456
                End Select
                returnvalue = returnvalue + (Position * CInt(multiplier))
            End If
        Next x
        hex_2_num = returnvalue
    Else
        MsgBox "This is not a valid hex value"
        'Call clearcontents
    End If
    hex_2_num = returnvalue
End Function

Function ConvertESN(strESN As String, strHex As String, strDec As String) As Boolean
    
    ConvertESN = False
    
    Select Case Len(strESN)
    
        Case Is = 11
            If IsNumeric(strESN) Then
                strHex = HEX(Left$(strESN, 3)) & HEX(Right$(strESN, 8))
                strDec = strESN
                ConvertESN = True
                If Len(strHex) > 8 Then ConvertESN = False
            End If
            
        Case Is = 8
            If IsValidHex(strESN) Then
                strDec = GetDecimal(strESN)
                strHex = strESN
                ConvertESN = True
            End If
        
    
    End Select
    
End Function


Function IsValidHex(strESN As String) As Boolean
    
    Dim intPos As Integer
    Dim strValidHexValues As String
    strValidHexValues = "0123456789ABCDEF"
    
    IsValidHex = True
    
    For intPos = 1 To Len(strESN)
        If InStr(strValidHexValues, Mid$(strESN, intPos, 1)) = 0 Then
            IsValidHex = False
            Exit Function
        End If
    Next
    
End Function




Function GetDecimal(strESN As String) As String


    Dim lngDecESN As Long
    Dim strHexValues As String
    strHexValues = "123456789ABCDEF"


' First two bytes
    lngDecESN = 16 * InStr(1, strHexValues, Mid$(strESN, 1, 1))
    lngDecESN = lngDecESN + InStr(1, strHexValues, Mid$(strESN, 2, 1))
    GetDecimal = lngDecESN


' Next six bytes
    lngDecESN = 1048576 * InStr(1, strHexValues, Mid$(strESN, 3, 1))
    lngDecESN = lngDecESN + 65536 * InStr(1, strHexValues, Mid$(strESN, 4, 1))
    lngDecESN = lngDecESN + 4096 * InStr(1, strHexValues, Mid$(strESN, 5, 1))
    lngDecESN = lngDecESN + 256 * InStr(1, strHexValues, Mid$(strESN, 6, 1))
    lngDecESN = lngDecESN + 16 * InStr(1, strHexValues, Mid$(strESN, 7, 1))
    lngDecESN = lngDecESN + InStr(1, strHexValues, Mid$(strESN, 8, 1))
' The above code will drop a leading zero in the "next six bytes".
' this next line of code was added to
' Handle 7-byte decimals - this is the only line I added ...
    If Left(Str(lngDecESN), 1) = " " Then GetDecimal = GetDecimal & "0"


    GetDecimal = GetDecimal & lngDecESN


End Function

Function H2D(s As String) As Variant
    Dim i As Long, sc As String
    
    For i = 1 To Len(s)
        sc = Mid(s, i, 1)
        Select Case sc
            Case "0" To "9": H2D = 16 * H2D + sc - 48
            Case "A" To "F": H2D = 16 * H2D + sc - 55
            Case "a" To "f": H2D = 16 * H2D + sc - 87
            Case Else
                H2D = "#VALUE!"
                Exit Function
        End Select
    Next
End Function

Function H2D(s As String) As Variant
    ' convert hex string to decimal
    Dim i As Long, sc As String


    For i = 1 To Len(s)
        sc = Mid(s, i, 1)
        Select Case sc
            Case "0" To "9": H2D = 16 * H2D + Asc(sc) - 48
            Case "A" To "F": H2D = 16 * H2D + Asc(sc) - 55
            Case "a" To "f": H2D = 16 * H2D + Asc(sc) - 87
            Case Else
                H2D = "#VALUE!"
                Exit Function
        End Select
    Next
End Function