' version 18-01-2017
' compile with: fbc -s console

Function gray2bin(g As UInteger) As UInteger

    Dim As UInteger b = g

    While g
        g Shr= 1
        b Xor= g
    Wend

    Return b

End Function

Function bin2gray(b As UInteger) As UInteger

    Return b Xor (b Shr 1)

End Function

' ------=< MAIN >=------

Dim As UInteger i

Print " i     binary     gray   gra2bin"
Print String(32,"=")

For i = 0 To 31
    Print Using "## --> "; i;
    print Bin(i,5); " --> ";
    Print Bin(bin2gray(i),5); " --> ";
    Print Bin(gray2bin(bin2gray(i)),5)
Next

' empty keyboard buffer
While Inkey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End