canister_controller

local lb,ub=0,4095
local delay=1
if lb<0 then lb=0 end
if ub>4095 then ub=4095 end

local cmp=component or require"component"
local comp=computer or require"computer"
local interrupt
local ut=comp.uptime
local sleep=function(secs) dl=ut()+secs;while ut()<dl do local s=comp.pullSignal(dl-ut()); if s=="interrupted" then interrupt(); dl=0 end end end
local et=cmp.proxy(cmp.list("ender_tank")())
local ga=function() return et.getTankInfo()[1].contents.amount end
local gc=function() return et.getTankInfo()[1].capacity end
local gf=function() return et.getFrequency() end
local sf=function(nf) et.setFrequency(nf) end
local chf=function(d) local cf=gf();local nf=cf+d;if nf>=lb and nf<=ub then sf(nf) end end

running=true
interrupt=function() running=false end

while running do
  if ga()<=0 then chf(-1)
  elseif ga()>=gc() then chf(1)
  end
  sleep(delay)
end