btnd.lua

-- helper function for buttons state
-- call btn_update ONCE per update
-- btnd returns true once the button is pressed down
-- btnu returns true when the button is released

do
 local state = {0,0,0,0,0,0}
 -- call this in _update! 
 btn_update=function ()
  for b=0,6 do
   if state[b] == 0 and btn(b) then
    state[b] = 1
   elseif state[b] == 1 then
    state[b] = 2
   elseif state[b] == 2 and not btn(b) then
    state[b] = 3
   elseif state[b] == 3 then
    state[b] = 0
   end
  end
 end

 btnd=function (b)
  return state[b] == 1
 end

 btnu=function (b)
  return state[b] == 3
 end
end

-- don't forget!
-- function _update()
--  btn_update()
-- end