Redstone-Event Extenstion API

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