Stopwatch Timer

-- Variable definitions
local monitor, screenw, screenh
local args = {...}
local sides = {"left", "right", "top", "bottom", "front", "back"};
local timing = false
local timer = 0
local best = -1
local starttime

local function getDeviceSide(deviceType)
    for i,side in pairs(sides) do
        if (peripheral.isPresent(side)) then
            if (peripheral.getType(side)) == string.lower(deviceType) then
                return side;
            end
        end
    end
end

local function displayTime(value)
    if (value) then
        print(value)
        term.redirect(monitor)
        monitor.setTextScale(5)
        monitor.setCursorPos(2, 2)
        monitor.clearLine()
        --write(string.format("%d%d.%d%d", value))
        write(value)
        term.restore()
    end
end

local function displayBest(value)
    if (value) then
        term.redirect(monitor)
        monitor.setTextScale(3)
        monitor.setCursorPos(1, 4)
        monitor.clearLine()
        --write(string.format("%d%d.%d%d", value))
        write("Best: " .. tostring(value))
        term.restore()
    end
end


local function mainLoop()
    while true do
        if (rs.getInput("top")) then
            if (timing) then
                local endtime = os.clock()
                final = endtime - starttime
                print("final: " .. tostring(final))
                if (final > 1) then -- ignore signals until the second second.
                    if (best == -1 or final < best) then
                        best = final
                        print("New best: " .. tostring(best))
                        displayBest(best)
                    end
                    timing = false
                    displayTime(final)
                    sleep(1)
                end
            else
                --monitor.clear()
                starttime = os.clock()
                timing = true
            end
        end
        if (timing) then
            local current = os.clock() - starttime
--          print("current time: " .. tostring(current))
            displayTime(current)
            sleep(.01)
        else
            sleep(.1)
        end
    end
end
---------------------------------------
--the Main
---------------------------------------
local screenSide = getDeviceSide("monitor");

if (screenSide) then
    monitor = peripheral.wrap(screenSide)
    if(not monitor.isColor()) then
        error("The attached monitor must be Advanced.  Get some gold!")
    end
    screenw, screenh = monitor.getSize()
    print("Monitor found, width: " .. tostring(screenw))
    print(monitor)
    monitor.setBackgroundColor(colors.black)
    monitor.setTextScale(5)
    monitor.clear()
else
    error("No attached monitor.  The timer needs a monitor.")
end

print("Waiting for a redstone signal.")
displayTime(0)
print("calling mainloop")
parallel.waitForAll(mainLoop)