[1.31] Redstone-Event Extension

local tRedstoneState = {}  -- Holds the state of all redstone sides on the computer.
local tCableState = {}  -- Holds the state of all bundled cables on the computer.

-- Get initial redstone state for all 6 sides.
for _, side in pairs( rs.getSides() ) do
  tRedstoneState[ side ] = rs.getInput( side )
end

-- Get initial bundled cable state for all 6 sides.
for _, v in pairs( rs.getSides() ) do
  tCableState[ v ] = rs.getBundledInput( v )
end

-- If a redstone side changes its state, then this function returns the event 'redstone' plus the string 'vanilla' and a table.
-- The returned table contains only sides that have changed and it has this format: { side = new_value }
-- If a bundled cable changes its state, then this function returns the event 'redstone' plus the string 'bundled_cable' and a table.
-- The returned table contains only sides that have changed and it has this format: { side = { new_value, old_value } }
function pullEvent( _sEvent, _tSide )
  local bRedstoneChanged = false
  local bCableChanged = false
  local tChangedCable = {}
  local tChangedRedstone = {}
  local event, p1, p2, p3, p4, p5 = os.pullEvent( _sEventFilter )

  local function checkRedstoneSides( _tSide )
	-- Iterate over all _tSide sides of the computer.
	-- If _tSide is not given, iterate over all 6 sides.
	for _, side in pairs( _tSide or rs.getSides() ) do
	  local bCurrentInput = rs.getInput( side )  -- Get redstone input for current side.

	  if bCurrentInput ~= tRedstoneState[ side ] then  -- Has the state changed?
		tChangedRedstone[ side ] = bCurrentInput  -- Add the changed side + its new value to the return table.
		tRedstoneState[ side ] = bCurrentInput  -- Update the local state table.
		bRedstoneChanged = true
	  end
	end
	return bRedstoneChanged, tChangedRedstone
  end

  local function checkBundledCableSides( _tSide )
	-- Iterate over all _tSide sides of the computer.
	-- If _tSide is not given, iterate over all 6 sides.
	for _, side in pairs( _tSide or rs.getSides() ) do
	  local nCableInput = rs.getBundledInput( side )  -- Get cable input for current side.

	  if nCableInput ~= tCableState[ side ] then  -- Has the state changed?
		tChangedCable[ side ] = { nCableInput, tCableState[ side ] }  -- Add the changed side + its new and old values to the return table.
		tCableState[ side ] = nCableInput  -- Update the local state table.
		bCableChanged = true
	  end
	end
	return bCableChanged, tChangedCable
  end

  if event == "redstone" then
	local bChanged, tSides = checkRedstoneSides( _tSide )
	if bChanged then return event, "vanilla", tSides, p2, p3, p4, p5 end

	local bChanged, tSides = checkBundledCableSides( _tSide )
	if bChanged then return event, "bundled_cable", tSides, p2, p3, p4, p5 end
  end

  return event, p1, p2, p3, p4, p5
end

term.clear()
term.setCursorPos(1, 1)

-- Load API
os.loadAPI("re")
if not re then
  error( "Redstone Event Extension API not loaded!" )
end

--[[ === MAIN LOOP === ]]
while true do
  local event, param1, param2 = re.pullEvent()

  if event == "redstone" then
	write( event..", "..param1..", " )
	if param1 == "vanilla" then
	  for sSide, bChanged in pairs( param2 ) do
		write( "{ "..sSide.." = "..tostring( bChanged ).." }" )
	  end
	end
	if param1 == "bundled_cable" then
	  local newValue = 1
	  local oldValue = 2
	  for sSide, tChanged in pairs( param2 ) do
		write( "{ "..sSide.." = { "..tostring( tChanged[newValue] )..", "..tostring( tChanged[oldValue] ).." } }" )
	  end
	end
	write( "n" )
  end

  if event == "char" and string.lower( param1 ) == "e" then break end  -- Pressing 'e' will exit the program.
end

-- Cleanup
os.unloadAPI( re )