startup

--IC2 Reinforced Stone automation
--Sand autonomous activator logic

--declare variables that persist across iterations
local pulseTriggered, foamState, activatorState = false, false, false

while true do
  local foamExists = rs.getInput("bottom")
  local activatorEmpty = rs.getInput("back")

--check if the input from CF Turtle master changed
  if foamExists ~= foamState then
    pulseTriggered = false
  end

--relay input to next computer
  rs.setOutput("top", foamExists)

--output signal to export bus if foam in system and activator is empty
  if not pulseTriggered then
    rs.setOutput("left", (foamExists and activatorEmpty))
    print("sand export = "..tostring((foamExists and activatorEmpty)))
  end

--update variables carried to next iteration
  if (foamExists and activatorEmpty) ~= (foamState and activatorState) then
    pulseTriggered = true
  end

  foamState = foamExists
  activatorState = activatorEmpty

--wait for redstone signal change
  os.pullEvent("redstone")
end