View difference between Paste ID: f2Jugase and vSEruxTz

 local tArgs = { ... }
 if #tArgs ~= 1 then
 	print( "Usage: excavate <diameter>" )
 	return
 end
 
 -- Mine in a quarry pattern until we hit something we can't dig
 local size = tonumber( tArgs[1] )
 if size < 1 then
 	print( "Excavate diameter must be positive" )
 	return
 end
 
 local depth = 0
 local collected = 0
 
 local xPos,zPos = 0,0
 local xDir,zDir = 0,1
 
 local function dropUseless()
 	local x = turtle.getItemCount(1);
 	if (x > 1) then
 		turtle.drop(x-1);
 	end
 end
 
 local function collect()
 	collected = collected + 1
 	if math.fmod(collected, 25) == 0 then
 		print( "Mined "..collected.." blocks." )
 	end
 
 	dropUseless();
 
 	for n=1,9 do
 		if turtle.getItemCount(n) == 0 then
 			return true
 		end
 	end
 
 	print( "No empty slots left." )
 	return false
 end
 
 local function tryForwards()
 	while not turtle.forward() do
 		if turtle.dig() then
 			if not collect() then
 				return false
 			end
 	    else
 			-- give sand a chance to fall
  			sleep(0.8)
 	    	if turtle.dig() then
 	    		if not collect() then
 					return false
 				end
 	    	else
 		    	return false
 		    end
 	    end
 	end
 	xPos = xPos + xDir
 	zPos = zPos + zDir
 	return true
 end
 
 local function tryDown()
 	if not turtle.down() then
 		if turtle.digDown() then
 			if not collect() then
 				return false
 			end
 	    end
 		if not turtle.down() then
 			return false
 		end
 	end
 	depth = depth + 1
 	if math.fmod( depth, 10 ) == 0 then
 		print( "Descended "..depth.." metres." )
 	end
 	return true
 end
 
 local function turnLeft()
 	turtle.turnLeft()
 	xDir, zDir = -zDir, xDir
 end
 
 local function turnRight()
 	turtle.turnRight()
 	xDir, zDir = zDir, -xDir
 end
 
 print( "Excavating..." )
 
 local reseal = false
 if turtle.digDown() then
 	reseal = true
 end
 
 local alternate = 0
 local done = false
 while not done do
 	for n=1,size do
 		for m=1,size-1 do
 			if not tryForwards() then
 				done = true
 				break
 			end
 		end
 		if done then
 			break
 		end
 		if n<size then
 			if math.fmod(n + alternate,2) == 0 then
 				turnLeft()
 				if not tryForwards() then
 					done = true
 					break
 				end
 				turnLeft()
 			else
 				turnRight()
 				if not tryForwards() then
 					done = true
 					break
 				end
 				turnRight()
 			end
 		end
 	end
 	if done then
 		break
 	end
 
 	if size > 1 then
 		if math.fmod(size,2) == 0 then
 			turnRight()
 		else
 			if alternate == 0 then
 				turnLeft()
 			else
 				turnRight()
 			end
 			alternate = 1 - alternate
 		end
 	end
 
 	if not tryDown() then
 		done = true
 		break
 	end
 end
 
 print( "Returning to surface..." )
 
 -- Return to where we started
 while depth > 0 do
 	if turtle.up() then
 		depth = depth - 1
 	elseif turtle.digUp() then
 		collect()
 	else
 		sleep( 0.5 )
 	end
 end
 
 if xPos > 0 then
 	while xDir ~= -1 do
 		turnLeft()
 	end
 	while xPos > 0 do
 		if turtle.forward() then
 			xPos = xPos - 1
 		elseif turtle.dig() then
 			collect()
 		else
 			sleep( 0.5 )
 		end
 	end
 end
 
 if zPos > 0 then
 	while zDir ~= -1 do
 		turnLeft()
 	end
 	while zPos > 0 do
 		if turtle.forward() then
 			zPos = zPos - 1
 		elseif turtle.dig() then
 			collected = collected + 1
 		else
 			sleep( 0.5 )
 		end
 	end
 end
 while zDir ~= 1 do
 	turnLeft()
 end
 
 -- Seal the hole
 if reseal then
 	turtle.placeDown()
 end