link bitint

procedure main()
    every write(right(i := 0 to 10,4),":",right(int2bit(i),10)," -> ",
                                          right(g := gEncode(i),10)," -> ",
                                          right(b := gDecode(g),10)," -> ",
                                          right(bit2int(b),10))
end

procedure gEncode(b)
    return int2bit(ixor(b, ishift(b,-1)))
end

procedure gDecode(g)
    b := g[1]
    every i := 2 to *g do b ||:= if g[i] == b[i-1] then "0" else "1"
    return b
end