#proto GrayEncode(_X_)
#synon _GrayEncode    *getGrayEncode
#proto GrayDecode(_X_)
#synon _GrayDecode    *getGrayDecode

#include <hbasic.h>

Begin
   Gray=0
   SizeBin(4)   // size 5 bits: 0->4
   Take (" #    BINARY   GRAY     DECODE\n")
   Take ("------------------------------\n"), and Print It
   For Up( i := 0, 31, 1)
      Print( LPad$(" ",2,Str$(i))," => ", Bin$(i)," => ")
      get Gray Encode(i) and Copy to (Gray), get Binary; then Take(" => ")
      now get Gray Decode( Gray ), get Binary, and Print It with a Newl
   Next
End

Subrutines

Gray Encode(n)
Return (XorBit( RShift(1,n), n ))

Gray Decode(n)
    p = n
    While ( n )
        n >>= 1
        p != n
    Wend
Return (p)