RosettaCodeData/Task/Gray-code/PowerBASIC/gray-code.basic

function gray%(byval n%)
  gray%=n% xor (n%\2)
end function

function igray%(byval n%)
  r%=0
  while n%>0
    r%=r% xor n%
    shift right n%,1
  wend
  igray%=r%
end function

print "   N  GRAY   INV"
for n%=0 to 31
  g%=gray%(n%)
  print bin$(n%);" ";bin$(g%);" ";bin$(igray%(g%))
next