skyscraper farm operation

-- Variables

turtle.select(1)
height = 0
local tArgs = { ... }
local levelAlt = tonumber(tArgs[1])

-- Functions

local function tMove(distance)
  for i=1,distance do
    while turtle.forward() == false do
      turtle.dig()
      turtle.attack()
      sleep(0.5)
    end
  end
end

local function tDescend(distance)
  for i=1,distance do
    while turtle.down() == false do
      turtle.digDown()
      turtle.attackDown()
      sleep(0.5)
    end
  end
end

local function tAscend(distance)
  for i=1,distance do
    while turtle.up() == false do
      turtle.digUp()
      turtle.attackUp()
      sleep(0.5)
    end
  end
end

local function turnaround()
  turtle.turnRight()
  turtle.turnRight()
end

local function tPlace()
    turtle.digDown()
  placedItem = 0
  for i=1,2 do
    if turtle.getItemCount(i) > 0 then
      if placedItem == 0 then
        turtle.select(i)
        turtle.placeDown()
        placedItem = 1
      end
    end
  end
  turtle.select(1)
end

local function tLineDraw(length)
  for i=1,length do
    tMove(1)
    tPlace()
  end
end

local function layCrop()
 turtle.turnLeft()
 tMove(4)
 turnaround()
  tPlace()
 -- Row 1
  tLineDraw(8)
  turtle.turnLeft()
  tLineDraw(1)
  turtle.turnLeft()
 -- Row 2
  tLineDraw(8)
  turtle.turnRight()
  tLineDraw(1)
  turtle.turnRight()
 -- Row 3
  tLineDraw(8)
  turtle.turnLeft()
  tLineDraw(1)
  turtle.turnLeft()
 -- Row 4
  tLineDraw(8)
  turtle.turnRight()
  tLineDraw(1)
  turtle.turnRight()
 -- Row 5 (Centre Block)
  tLineDraw(3)
  turtle.turnRight()
  tMove(1)
  turtle.turnLeft()
  tMove(2)
  turtle.turnLeft()
  tMove(1)
  turtle.turnRight()
  tPlace()
  tLineDraw(3)
  turtle.turnLeft()
  tLineDraw(1)
  turtle.turnLeft()
 -- Row 6
  tLineDraw(8)
  turtle.turnRight()
  tLineDraw(1)
  turtle.turnRight()
 -- Row 7
  tLineDraw(8)
  turtle.turnLeft()
  tLineDraw(1)
  turtle.turnLeft()
 -- Row 8
  tLineDraw(8)
  turtle.turnRight()
  tLineDraw(1)
  turtle.turnRight()
 -- Row 9
  tLineDraw(8)
  turtle.turnRight()
  tMove(8)
 -- Return to Door
  turtle.turnRight()
  tMove(4)
  turtle.turnLeft()
  tMove(2)
end

-- Startup

 term.clear()
 term.setCursorPos(1,1)
 print("Please place blocks as follows:")
 print("Slot 1 and 2 - Seeds")
 print()
 print("Ground Level = 0")
 print("Press enter a level when ready:")
 level = read(input)

-- Main Program
tAscend(4*level + 1)
tMove(2)
layCrop()
tDescend(4*level + 1)
turnaround()
for i=3,16 do
  turtle.select(i)
  turtle.dropDown()
end
turtle.select(1)