[Minecraft] Ore Quarry

-- ********************************************************************************** --
-- **                                                                              ** --
-- **   Minecraft Mining Turtle Ore Quarry v0.71 by AustinKK (Modified by WillisS) ** --
-- **   (Add fuel control and broadcast location function)                         ** --
-- **   ----------------------------------------------------                       ** --
-- **                                                                              ** --
-- **   For instructions on how to use:                                            ** --
-- **                                                                              ** --
-- **     http://www.youtube.com/watch?v=PIugLVzUz3g                               ** --
-- **                                                                              ** --
-- **  Change Log:                                                                 ** --
-- **    27th Dec 2012: [v0.2] Initial Draft Release                               ** --
-- **    29th Dec 2012: [v0.3] Minor Performance Improvements                      ** --
-- **    30th Dec 2012: [v0.4] Further Performance Improvements                    ** --
-- **    9th  Jan 2013: [v0.5] Debug Version (dropping off chest)                  ** --
-- **    10th Jan 2013: [v0.51] Further Debug (dropping off chest)                 ** --
-- **    10th Jan 2013: [v0.52] Fix for dropping off chest bug                     ** --
-- **    11th Jan 2013: [v0.53] Fix for dropping off chest bug (release)           ** --
-- **    12th Jan 2013: [v0.6] Added support for resume                            ** --
-- **    31st Mar 2013: [v0.7] Fixes for ComputerCraft 1.52                        ** --
-- **    25th Aug 2013: [v0.71] Support ComputerCraft 1.56 and Chunk Loader Module ** --
-- **                                                                              ** --
-- ********************************************************************************** --


-- ********************************************************************************** --
-- Note: If you are in a world with flat bedrock, change the value below from 5 to 2.
--       You don't need to change this, but the turtle is slightly faster if you do.
-- ********************************************************************************** --
local bottomLayer = 2 -- The y co-ords of the layer immediately above bedrock



-- Enumeration to store the the different types of message that can be written
messageLevel = { DEBUG=0, INFO=1, WARNING=2, ERROR=3, FATAL=4 }

-- Enumeration to store names for the 6 directions
direction = { FORWARD=0, RIGHT=1, BACK=2, LEFT=3, UP=4, DOWN=5 }

-- Enumeration of mining states
miningState = { START=0, LAYER=1, EMPTYCHESTDOWN=2, EMPTYINVENTORY=3 }

local messageOutputLevel = messageLevel.INFO
local messageOutputFileName
local fuelLevelToRefuelAt = 100
local refuelItemsToUseWhenRefuelling = 20
local emergencyFuelToRetain = 3
local maximumGravelStackSupported = 25 -- The number of stacked gravel or sand blocks supported
local noiseBlocksCount
local returningToStart = false
local lookForChests = false -- Determines if chests should be located as part of the quarrying
local miningOffset -- The offset to the mining layer. This is set depending on whether chests are being looked for or not
local lastEmptySlot -- The last inventory slot that was empty when the program started (is either 15 if not looking for chests or 14 if we are)
local turtleId
local isWirelessTurtle
local currentlySelectedSlot = 0 -- The slot that the last noise block was found in
local lastMoveNeededDig = true -- Determines whether the last move needed a dig first
local haveBeenAtZeroZeroOnLayer -- Determines whether the turtle has been at (0, 0) in this mining layer
local orientationAtZeroZero -- The turtle's orientation when it was at (0, 0)
local levelToReturnTo -- The level that the turtle should return to in order to head back to the start to unload
local isGPSlost -- whether GPS is lost

-- Variables used to support a resume
local startupParamsFile = "OreQuarryParams.txt"
local oreQuarryLocation = "OreQuarryLocation.txt"
local returnToStartFile = "OreQuarryReturn.txt"
local startupBackup = "startup_bak"
local supportResume = true -- Determines whether the turtle is being run in the mode that supports resume
local resuming = false -- Determines whether the turtle is currently in the process of resuming
local resumeX
local resumeY
local resumeZ
local resumeOrient
local resumeMiningState

-- Variables to store the current location and orientation of the turtle. x is right, left, y is up, down and
-- z is forward, back with relation to the starting orientation. Y is the actual turtle level, x and z are
-- in relation to the starting point (i.e. the starting point is (0, 0))
local currX
local currY
local currZ
local currOrient
local currMiningState = miningState.START

-- Command line parameters
local startHeight -- Represents the height (y co-ord) that the turtle started at
local quarryWidth -- Represents the length of the mines that the turtle will dig

-- ********************************************************************************** --
-- Writes an output message
-- ********************************************************************************** --
function writeMessage(message, msgLevel)
	if (msgLevel >= messageOutputLevel) then
		print(message)

		-- If this turtle has a modem, then write the message to red net
		if (isWirelessTurtle == true) then
			if (turtleId == nil) then
				rednet.broadcast(message)
			else
				-- Broadcast the message (prefixed with the turtle's id)
				rednet.broadcast("[".. turtleId.."] "..message)
			end
		end

		if (messageOutputFileName ~= nil) then
			-- Open file, write message and close file (flush doesn't seem to work!)
			local outputFile
			if (fs.exists(messageOutputFileName) == true) then
				outputFile = io.open(messageOutputFileName, "a")
			else
				outputFile = io.open(messageOutputFileName, "w")
			end

			outputFile:write(message)
			outputFile:write("\n")
			outputFile:close()
		end
	end
end

-- ********************************************************************************** --
-- Ensures that the turtle has fuel
-- ********************************************************************************** --
function ensureFuel()

	-- Determine whether a refuel is required
	local fuelLevel = turtle.getFuelLevel()
	if (fuelLevel ~= "unlimited") then
		if (fuelLevel < fuelLevelToRefuelAt) then
			-- Need to refuel
			turtle.select(16)
			currentlySelectedSlot = 16
			local fuelItems = turtle.getItemCount(16)

			-- Do we need to impact the emergency fuel to continue? (always
			-- keep one fuel item in slot 16)
			if (fuelItems == 0) then
				writeMessage("Completely out of fuel!", messageLevel.FATAL)
			elseif (fuelItems == 1) then
				writeMessage("Out of Fuel!", messageLevel.ERROR)
				turtle.refuel()
			elseif (fuelItems <= (emergencyFuelToRetain + 1)) then
				writeMessage("Consuming emergency fuel supply. "..(fuelItems - 2).." emergency fuel items remain", messageLevel.WARNING)
				turtle.refuel(1)
				if returningToStart ~= true then
					returnToStartAndUnload(true)
				end
			else
				-- Refuel the lesser of the refuelItemsToUseWhenRefuelling and the number of items more than
				-- the emergency fuel level
				if (fuelItems - (emergencyFuelToRetain + 1) < refuelItemsToUseWhenRefuelling) then
					turtle.refuel(fuelItems - (emergencyFuelToRetain + 1))
				else
					turtle.refuel(refuelItemsToUseWhenRefuelling)
				end
			end
		end
	end
end

-- ********************************************************************************** --
-- Checks that the turtle has inventory space by checking for spare slots and returning
-- to the starting point to empty out if it doesn't.
--
-- Takes the position required to move to in order to empty the turtle's inventory
-- should it be full as arguments
-- ********************************************************************************** --
function ensureInventorySpace()

	-- If already returning to start, then don't need to do anything
	if (returningToStart == false) then

		-- If the last inventory slot is full, then need to return to the start and empty
		if (turtle.getItemCount(lastEmptySlot) > 0) then

			-- Return to the starting point and empty the inventory, then go back to mining
			returnToStartAndUnload(true)
		end
	end
end

-- ********************************************************************************** --
-- Function to move to the starting point, call a function that is passed in
-- and return to the same location (if required)
-- ********************************************************************************** --
function returnToStartAndUnload(returnBackToMiningPoint)

	writeMessage("returnToStartAndUnload called", messageLevel.DEBUG)
	returningToStart = true
	local storedX, storedY, storedZ, storedOrient
	local prevMiningState = currMiningState

	if (resuming == true) then
		-- Get the stored parameters from the necessary file
		local resumeFile = fs.open(returnToStartFile, "r")
		if (resumeFile ~= nil) then
			-- Restore the parameters from the file
			local beenAtZero = resumeFile.readLine()
			if (beenAtZero == "y") then
				haveBeenAtZeroZeroOnLayer = true
			else
				haveBeenAtZeroZeroOnLayer = false
			end

			local miningPointFlag = resumeFile.readLine()
			if (miningPointFlag == "y") then
				returnBackToMiningPoint = true
			else
				returnBackToMiningPoint = false
			end

			currX = readNumber(resumeFile)
			currY = readNumber(resumeFile)
			currZ = readNumber(resumeFile)
			currOrient = readNumber(resumeFile)
			levelToReturnTo = readNumber(resumeFile)
			prevMiningState = readNumber(resumeFile)
			orientationAtZeroZero = readNumber(resumeFile)
			resumeFile.close()

		else
			writeMessage("Failed to read return to start file", messageLevel.ERROR)
		end
	elseif (supportResume == true) then

		local outputFile = io.open(returnToStartFile, "w")

		if (haveBeenAtZeroZeroOnLayer == true) then
			outputFile:write("y\n")
		else
			outputFile:write("n\n")
		end
		if (returnBackToMiningPoint == true) then
			outputFile:write("y\n")
		else
			outputFile:write("n\n")
		end

		outputFile:write(currX)
		outputFile:write("\n")
		outputFile:write(currY)
		outputFile:write("\n")
		outputFile:write(currZ)
		outputFile:write("\n")
		outputFile:write(currOrient)
		outputFile:write("\n")
		outputFile:write(levelToReturnTo)
		outputFile:write("\n")
		outputFile:write(prevMiningState)
		outputFile:write("\n")
		outputFile:write(orientationAtZeroZero)
		outputFile:write("\n")

		outputFile:close()
	end

	storedX = currX
	storedY = currY
	storedZ = currZ
	storedOrient = currOrient

	-- Store the current location and orientation so that it can be returned to
	currMiningState = miningState.EMPTYINVENTORY
	writeMessage("last item count = "..turtle.getItemCount(lastEmptySlot), messageLevel.DEBUG)

	if ((turtle.getItemCount(lastEmptySlot) > 0) or (returnBackToMiningPoint == false)) then

		writeMessage("Heading back to surface", messageLevel.DEBUG)

		-- Move down to the correct layer to return via
		if (currY > levelToReturnTo) then
			while (currY > levelToReturnTo) do
				turtleDown()
			end
		elseif (currY < levelToReturnTo) then
			while (currY < levelToReturnTo) do
				turtleUp()
			end
		end

		if ((haveBeenAtZeroZeroOnLayer == false) or (orientationAtZeroZero == direction.FORWARD)) then
			-- Move back to the correct X position first
			if (currX > 0) then
				turtleSetOrientation(direction.LEFT)
				while (currX > 0) do
					turtleForward()
				end
			elseif (currX < 0) then
				-- This should never happen
				writeMessage("Current x is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
			end

			-- Then move back to the correct Z position
			if (currZ > 0) then
				turtleSetOrientation(direction.BACK)
				while (currZ > 0) do
					turtleForward()
				end
			elseif (currZ < 0) then
				-- This should never happen
				writeMessage("Current z is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
			end
		else
			-- Move back to the correct Z position first
			if (currZ > 0) then
				turtleSetOrientation(direction.BACK)
				while (currZ > 0) do
					turtleForward()
				end
			elseif (currZ < 0) then
				-- This should never happen
				writeMessage("Current z is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
			end

			-- Then move back to the correct X position
			if (currX > 0) then
				turtleSetOrientation(direction.LEFT)
				while (currX > 0) do
					turtleForward()
				end
			elseif (currX < 0) then
				-- This should never happen
				writeMessage("Current x is less than 0 in returnToStartAndUnload", messageLevel.ERROR)
			end
		end

		-- Return to the starting layer
		if (currY < startHeight) then
			while (currY < startHeight) do
				turtleUp()
			end
		elseif (currY > startHeight) then
			-- This should never happen
			writeMessage("Current height is greater than start height in returnToStartAndUnload", messageLevel.ERROR)
		end

		-- Empty the inventory
		local slotLoop = 1

		-- Face the chest
		turtleSetOrientation(direction.BACK)

		-- Loop over each of the slots (except the 16th one which stores fuel)
		while (slotLoop < 16) do
			-- If this is one of the slots that contains a noise block, empty all blocks except
			-- one
			turtle.select(slotLoop) -- Don't bother updating selected slot variable as it will set later in this function
			if ((slotLoop <= noiseBlocksCount) or ((slotLoop == 15) and (lastEmptySlot == 14))) then
				writeMessage("Dropping (n-1) from slot "..slotLoop.." ["..turtle.getItemCount(slotLoop).."]", messageLevel.DEBUG)
				if (turtle.getItemCount(slotLoop) > 0) then
					turtle.drop(turtle.getItemCount(slotLoop) - 1)
				end
			else
				-- Not a noise block, drop all of the items in this slot
				writeMessage("Dropping (all) from slot "..slotLoop.." ["..turtle.getItemCount(slotLoop).."]", messageLevel.DEBUG)
				if (turtle.getItemCount(slotLoop) > 0) then
					turtle.drop()
				end
			end

			slotLoop = slotLoop + 1
		end

		-- While we are here, refill the fuel items if there is capacity
		if (turtle.getItemCount(16) < 64) then
			turtleSetOrientation(direction.LEFT)
			turtle.select(16) -- Don't bother updating selected slot variable as it will set later in this function
			local currFuelItems = turtle.getItemCount(16)
			turtle.suck()
			while ((currFuelItems ~= turtle.getItemCount(16)) and (turtle.getItemCount(16) < 64)) do
				currFuelItems = turtle.getItemCount(16)
				turtle.suck()
			end

			slotLoop = noiseBlocksCount + 1
			-- Have now picked up all the items that we can. If we have also picked up some
			-- additional fuel in some of the other slots, then drop it again
			while (slotLoop <= lastEmptySlot) do
				-- Drop any items found in this slot
				if (turtle.getItemCount(slotLoop) > 0) then
					turtle.select(slotLoop) -- Don't bother updating selected slot variable as it will set later in this function
					turtle.drop()
				end
				slotLoop = slotLoop + 1
			end
		end

		-- Select the 1st slot because sometimes when leaving the 15th or 16th slots selected it can result
		-- in that slot being immediately filled (resulting in the turtle returning to base again too soon)
		turtle.select(1)
		currentlySelectedSlot = 1
	end

	-- If required, move back to the point that we were mining at before returning to the start
	if (returnBackToMiningPoint == true) then

		-- If resuming, refresh the starting point to be the top of the return shaft
		if (resuming == true) then
			currX = 0
			currY = startHeight
			currZ = 0
			currOrient = resumeOrient
		end

		-- Return back to the required layer
		while (currY > levelToReturnTo) do
			turtleDown()
		end

		if ((haveBeenAtZeroZeroOnLayer == false) or (orientationAtZeroZero == direction.FORWARD)) then
			-- Move back to the correct Z position first
			writeMessage("Stored Z: "..storedZ..", currZ: "..currZ, messageLevel.DEBUG)
			if (storedZ > currZ) then
				writeMessage("Orienting forward", messageLevel.DEBUG)
				writeMessage("Moving in z direction", messageLevel.DEBUG)
				turtleSetOrientation(direction.FORWARD)
				while (storedZ > currZ) do
					turtleForward()
				end
			elseif (storedZ < currZ) then
				-- This should never happen
				writeMessage("Stored z is less than current z in returnToStartAndUnload", messageLevel.ERROR)
			end

			-- Then move back to the correct X position
			if (storedX > currX) then
				writeMessage("Stored X: "..storedX..", currX: "..currX, messageLevel.DEBUG)
				writeMessage("Orienting right", messageLevel.DEBUG)
				writeMessage("Moving in x direction", messageLevel.DEBUG)
				turtleSetOrientation(direction.RIGHT)
				while (storedX > currX) do
					turtleForward()
				end
			elseif (storedX < currX) then
				-- This should never happen
				writeMessage("Stored x is less than current x in returnToStartAndUnload", messageLevel.ERROR)
			end
		else
			-- Move back to the correct X position first
			if (storedX > currX) then
				writeMessage("Stored X: "..storedX..", currX: "..currX, messageLevel.DEBUG)
				writeMessage("Orienting right", messageLevel.DEBUG)
				writeMessage("Moving in x direction", messageLevel.DEBUG)
				turtleSetOrientation(direction.RIGHT)
				while (storedX > currX) do
					turtleForward()
				end
			elseif (storedX < currX) then
				-- This should never happen
				writeMessage("Stored x is less than current x in returnToStartAndUnload", messageLevel.ERROR)
			end

			-- Then move back to the correct Z position
			writeMessage("Stored Z: "..storedZ..", currZ: "..currZ, messageLevel.DEBUG)
			if (storedZ > currZ) then
				writeMessage("Orienting forward", messageLevel.DEBUG)
				writeMessage("Moving in z direction", messageLevel.DEBUG)
				turtleSetOrientation(direction.FORWARD)
				while (storedZ > currZ) do
					turtleForward()
				end
			elseif (storedZ < currZ) then
				-- This should never happen
				writeMessage("Stored z is less than current z in returnToStartAndUnload", messageLevel.ERROR)
			end
		end

		-- Move back to the correct layer
		if (storedY < currY) then
			while (storedY < currY) do
				turtleDown()
			end
		elseif (storedY > currY) then
			while (storedY > currY) do
				turtleUp()
			end
		end

		-- Finally, set the correct orientation
		turtleSetOrientation(storedOrient)

		writeMessage("Have returned to the mining point", messageLevel.DEBUG)
	end

	-- Store the current location and orientation so that it can be returned to
	currMiningState = prevMiningState

	returningToStart = false

end

-- ********************************************************************************** --
-- Empties a chest's contents
-- ********************************************************************************** --
function emptyChest(suckFn)

	local prevInventoryCount = {}
	local inventoryLoop
	local chestEmptied = false

	-- Record the number of items in each of the inventory slots
	for inventoryLoop = 1, 16 do
		prevInventoryCount[inventoryLoop] = turtle.getItemCount(inventoryLoop)
	end

	while (chestEmptied == false) do
		-- Pick up the next item
		suckFn()

		-- Determine the number of items in each of the inventory slots now
		local newInventoryCount = {}
		for inventoryLoop = 1, 16 do
			newInventoryCount[inventoryLoop] = turtle.getItemCount(inventoryLoop)
		end

		-- Now, determine whether there have been any items taken from the chest
		local foundDifferentItemCount = false
		inventoryLoop = 1
		while ((foundDifferentItemCount == false) and (inventoryLoop <= 16)) do
			if (prevInventoryCount[inventoryLoop] ~= newInventoryCount[inventoryLoop]) then
				foundDifferentItemCount = true
			else
				inventoryLoop = inventoryLoop + 1
			end
		end

		-- If no items have been found with a different item count, then the chest has been emptied
		chestEmptied = not foundDifferentItemCount

		if (chestEmptied == false) then
			prevInventoryCount = newInventoryCount
			-- Check that there is sufficient inventory space as may have picked up a block
			ensureInventorySpace()
		end
	end

	writeMessage("Finished emptying chest", messageLevel.DEBUG)
end

-- ********************************************************************************** --
-- Write the current location to a file
-- ********************************************************************************** --
function saveLocation()

	-- Write the x, y, z and orientation to the file
	if ((supportResume == true) and (resuming == false)) then
		local outputFile = io.open(oreQuarryLocation, "w")
		outputFile:write(currMiningState)
		outputFile:write("\n")
		outputFile:write(currX)
		outputFile:write("\n")
		outputFile:write(currY)
		outputFile:write("\n")
		outputFile:write(currZ)
		outputFile:write("\n")
		outputFile:write(currOrient)
		outputFile:write("\n")
		outputFile:close()
	end

end

-- ********************************************************************************** --
-- If the turtle is resuming and the current co-ordinates, orientation and
-- mining state have been matched, then no longer resuming
-- ********************************************************************************** --
function updateResumingFlag()

	if (resuming == true) then
		if ((resumeMiningState == currMiningState) and (resumeX == currX) and (resumeY == currY) and (resumeZ == currZ) and (resumeOrient == currOrient)) then
			resuming = false
		end
	end

end

-- ********************************************************************************** --
-- Generic function to move the Turtle (pushing through any gravel or other
-- things such as mobs that might get in the way).
--
-- The only thing that should stop the turtle moving is bedrock. Where this is
-- found, the function will return after 15 seconds returning false
-- ********************************************************************************** --
function moveTurtle(moveFn, detectFn, digFn, attackFn, compareFn, suckFn, maxDigCount, newX, newY, newZ)

	local moveSuccess = false

	-- If we are resuming, then don't do anything in this function other than updating the
	-- co-ordinates as if the turtle had moved
	if (resuming == true) then
		-- Set the move success to true (but don't move) - unless this is below bedrock level
		-- in which case return false
		if (currY <= 0) then
			moveSuccess = false
		else
			moveSuccess = true
		end

		-- Update the co-ordinates to reflect the movement
		currX = newX
		currY = newY
		currZ = newZ

	else
		local prevX, prevY, prevZ
		prevX = currX
		prevY = currY
		prevZ = currZ

		ensureFuel()

		-- Flag to determine whether digging has been tried yet. If it has
		-- then pause briefly before digging again to allow sand or gravel to
		-- drop
		local digCount = 0

		if (lastMoveNeededDig == false) then
			-- Didn't need to dig last time the turtle moved, so try moving first

			currX = newX
			currY = newY
			currZ = newZ
			saveLocation()

			moveSuccess = moveFn()

			-- If move failed, update the co-ords back to the previous co-ords
			if (moveSuccess == false) then
				currX = prevX
				currY = prevY
				currZ = prevZ
				saveLocation()
			end

			-- Don't need to set the last move needed dig. It is already false, if
			-- move success is now true, then it won't be changed
		else
			-- If we are looking for chests, then check that this isn't a chest before trying to dig it
			if (lookForChests == true) then
				if (isNoiseBlock(compareFn) == false) then
					if (detectFn() == true) then
						-- Determine if it is a chest before digging it
						if (isChestBlock(compareFn) == true) then
							-- Have found a chest, empty it before continuing
							emptyChest (suckFn)
						end
					end
				end
			end

			-- Try to dig (without doing a detect as it is quicker)
			local digSuccess = digFn()
			if (digSuccess == true) then
				digCount = 1
			end

			currX = newX
			currY = newY
			currZ = newZ
			saveLocation()

			moveSuccess = moveFn()

			if (moveSuccess == true) then
				lastMoveNeededDig = digSuccess
			else
				currX = prevX
				currY = prevY
				currZ = prevZ
				saveLocation()
			end

		end

		-- Loop until we've successfully moved
		if (moveSuccess == false) then
			while ((moveSuccess == false) and (digCount < maxDigCount)) do

				-- If there is a block in front, dig it
				if (detectFn() == true) then

						-- If we've already tried digging, then pause before digging again to let
						-- any sand or gravel drop, otherwise check for a chest before digging
						if(digCount == 0) then
							-- Am about to dig a block - check that it is not a chest if necessary
							-- If we are looking for chests, then check that this isn't a chest before moving
							if (lookForChests == true) then
								if (isNoiseBlock(compareFn) == false) then
									if (detectFn() == true) then
										-- Determine if it is a chest before digging it
										if (isChestBlock(compareFn) == true) then
											-- Have found a chest, empty it before continuing
											emptyChest (suckFn)
										end
									end
								end
							end
						else
							sleep(0.1)
						end

						digFn()
						digCount = digCount + 1
				else
					 -- Am being stopped from moving by a mob, attack it
					 attackFn()
				end

				currX = newX
				currY = newY
				currZ = newZ
				saveLocation()

				-- Try the move again
				moveSuccess = moveFn()

				if (moveSuccess == false) then
					currX = prevX
					currY = prevY
					currZ = prevZ
					saveLocation()
				end
			end

			if (digCount == 0) then
				lastMoveNeededDig = false
			else
				lastMoveNeededDig = true
			end
		end
	end

	-- If we are resuming and the current co-ordinates and orientation are the resume point
	-- then are no longer resuming
	if (moveSuccess == true) then
		updateResumingFlag()
		-- broadcast gps location"
		if (isWirelessTurtle == true) then
			local x, y, z = gps.locate()
			if (x~=nil and y~=nil and z~=nil) then
				isGPSlost = nil
				rednet.broadcast(turtleId.." is now at ("..x..", "..y..", "..z..")")
			else
				-- only broadcast lost signal once
				if (isGPSlost == nil) then
					rednet.broadcast(turtleId..": GPS lost")
				end
				isGPSlost = true
			end
		end
	end

	-- Return the move success
	return moveSuccess

end

-- ********************************************************************************** --
-- Move the turtle forward one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleForward()

	-- Determine the new co-ordinate that the turtle will be moving to
	local newX, newZ

	-- Update the current co-ordinates
	if (currOrient == direction.FORWARD) then
		newZ = currZ + 1
		newX = currX
	elseif (currOrient == direction.LEFT) then
		newX = currX - 1
		newZ = currZ
	elseif (currOrient == direction.BACK) then
		newZ = currZ - 1
		newX = currX
	elseif (currOrient == direction.RIGHT) then
		newX = currX + 1
		newZ = currZ
	else
		writeMessage ("Invalid currOrient in turtleForward function", messageLevel.ERROR)
	end

	local returnVal = moveTurtle(turtle.forward, turtle.detect, turtle.dig, turtle.attack, turtle.compare, turtle.suck, maximumGravelStackSupported, newX, currY, newZ)

	if (returnVal == true) then
		-- Check that there is sufficient inventory space as may have picked up a block
		ensureInventorySpace()
	end

	return returnVal
end

-- ********************************************************************************** --
-- Move the turtle up one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleUp()

	local returnVal = moveTurtle(turtle.up, turtle.detectUp, turtle.digUp, turtle.attackUp, turtle.compareUp, turtle.suckUp, maximumGravelStackSupported, currX, currY + 1, currZ)

	if (returnVal == true) then
		-- Check that there is sufficient inventory space as may have picked up a block
		ensureInventorySpace()
	end

	return returnVal
end

-- ********************************************************************************** --
-- Move the turtle down one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleDown()

	local returnVal = moveTurtle(turtle.down, turtle.detectDown, turtle.digDown, turtle.attackDown, turtle.compareDown, turtle.suckDown, 1, currX, currY - 1, currZ)

	if (returnVal == true) then
		-- Check that there is sufficient inventory space as may have picked up a block
		ensureInventorySpace()
	end

	return returnVal

end

-- ********************************************************************************** --
-- Move the turtle back one block (updating the turtle's position)
-- ********************************************************************************** --
function turtleBack()

	-- Assume that the turtle will move, and switch the co-ords back if it doesn't
	-- (do this so that we can write the co-ords to a file before moving)
	local newX, newZ
	local prevX, prevZ
	prevX = currX
	prevZ = currZ

	-- Update the current co-ordinates
	if (currOrient == direction.FORWARD) then
		newZ = currZ - 1
		newX = currX
	elseif (currOrient == direction.LEFT) then
		newX = currX + 1
		newZ = currZ
	elseif (currOrient == direction.BACK) then
		newZ = currZ + 1
		newX = currX
	elseif (currOrient == direction.RIGHT) then
		newX = currX - 1
		newZ = currZ
	else
		writeMessage ("Invalid currOrient in turtleBack function", messageLevel.ERROR)
	end

	-- First try to move back using the standard function

	currX = newX
	currZ = newZ
	saveLocation()
	local returnVal = turtle.back()

	if (returnVal == false) then
		-- Didn't move. Reset the co-ordinates to the previous value
		currX = prevX
		currZ = prevZ

		-- Reset the location back to the previous location (because the turn takes 0.8 of a second
		-- so could be stopped before getting to the forward function)
		saveLocation()

		turtle.turnRight()
		turtle.turnRight()

		-- Try to move by using the forward function (note, the orientation will be set as
		-- the same way as this function started because if the function stops, that is the
		-- direction that we want to consider the turtle to be pointing)

		returnVal = moveTurtle(turtle.forward, turtle.detect, turtle.dig, turtle.attack, turtle.compare, turtle.suck, maximumGravelStackSupported, newX, currY, newZ)

		turtle.turnRight()
		turtle.turnRight()
	end

	if (returnVal == true) then
		-- Check that there is sufficient inventory space as may have picked up a block
		ensureInventorySpace()
	end

	return returnVal
end

-- ********************************************************************************** --
-- Turns the turtle (updating the current orientation at the same time)
-- ********************************************************************************** --
function turtleTurn(turnDir)

	if (turnDir == direction.LEFT) then
		if (currOrient == direction.FORWARD) then
			currOrient = direction.LEFT
		elseif (currOrient == direction.LEFT) then
			currOrient = direction.BACK
		elseif (currOrient == direction.BACK) then
			currOrient = direction.RIGHT
		elseif (currOrient == direction.RIGHT) then
			currOrient = direction.FORWARD
		else
			writeMessage ("Invalid currOrient in turtleTurn function", messageLevel.ERROR)
		end

		-- If we are resuming, just check to see whether have reached the resume point, otherwise
		-- turn
		if (resuming == true) then
			updateResumingFlag()
		else
			-- Write the new orientation and turn
			saveLocation()
			turtle.turnLeft()
		end

	elseif (turnDir == direction.RIGHT) then
		if (currOrient == direction.FORWARD) then
			currOrient = direction.RIGHT
		elseif (currOrient == direction.LEFT) then
			currOrient = direction.FORWARD
		elseif (currOrient == direction.BACK) then
			currOrient = direction.LEFT
		elseif (currOrient == direction.RIGHT) then
			currOrient = direction.BACK
		else
			writeMessage ("Invalid currOrient in turtleTurn function", messageLevel.ERROR)
		end

		-- If we are resuming, just check to see whether have reached the resume point, otherwise
		-- turn
		if (resuming == true) then
			updateResumingFlag()

			writeMessage("["..currMiningState..", "..currX..", "..currY..", "..currZ..", "..currOrient.."]", messageLevel.DEBUG)
		else
			-- Write the new orientation and turn
			saveLocation()
			turtle.turnRight()
		end
	else
		writeMessage ("Invalid turnDir in turtleTurn function", messageLevel.ERROR)
	end
end

-- ********************************************************************************** --
-- Sets the turtle to a specific orientation, irrespective of its current orientation
-- ********************************************************************************** --
function turtleSetOrientation(newOrient)

	if (currOrient ~= newOrient) then
		if (currOrient == direction.FORWARD) then
			if (newOrient == direction.RIGHT) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
				end
			elseif (newOrient == direction.BACK) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
					turtle.turnRight()
				end
			elseif (newOrient == direction.LEFT) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnLeft()
				end
			else
				writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
			end
		elseif (currOrient == direction.RIGHT) then
			if (newOrient == direction.BACK) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
				end
			elseif (newOrient == direction.LEFT) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
					turtle.turnRight()
				end
			elseif (newOrient == direction.FORWARD) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnLeft()
				end
			else
				writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
			end
		elseif (currOrient == direction.BACK) then
			if (newOrient == direction.LEFT) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
				end
			elseif (newOrient == direction.FORWARD) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
					turtle.turnRight()
				end
			elseif (newOrient == direction.RIGHT) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnLeft()
				end
			else
				writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
			end
		elseif (currOrient == direction.LEFT) then
			if (newOrient == direction.FORWARD) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
				end
			elseif (newOrient == direction.RIGHT) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnRight()
					turtle.turnRight()
				end
			elseif (newOrient == direction.BACK) then
				currOrient = newOrient

				-- If resuming, check whether the resume point has been reached, otherwise turn
				if (resuming == true) then
					updateResumingFlag()
				else
					-- Write the new orientation and turn
					saveLocation()
					turtle.turnLeft()
				end
			else
				writeMessage ("Invalid newOrient in turtleSetOrientation function", messageLevel.ERROR)
			end
		else
			writeMessage ("Invalid currOrient in turtleTurn function", messageLevel.ERROR)
		end
	end
end

-- ********************************************************************************** --
-- Determines if a particular block is considered a noise block or not. A noise
-- block is one that is a standard block in the game (stone, dirt, gravel etc.) and
-- is one to ignore as not being an ore. Function works by comparing the block
-- in question against a set of blocks in the turtle's inventory which are known not to
-- be noise blocks. Param is the function to use to compare the block for a noise block
-- ********************************************************************************** --
function isNoiseBlock(compareFn)

	-- Consider air to be a noise block
	local returnVal = false

	if (resuming == true) then
		returnVal = true
	else
		local seamLoop = 1
		local prevSelectedSlot

		-- If the currently selected slot is a noise block, then compare against this first
		-- so that the slot doesn't need to be selected again (there is a 0.05s cost to do
		-- this even if it is the currently selected slot)
		if (currentlySelectedSlot <= noiseBlocksCount) then
			returnVal = compareFn()
		end

		if (returnVal == false) then
			prevSelectedSlot = currentlySelectedSlot
			while((returnVal == false) and (seamLoop <= noiseBlocksCount)) do
				if (seamLoop ~= prevSelectedSlot) then
					turtle.select(seamLoop)
					currentlySelectedSlot = seamLoop
					returnVal = compareFn()
				end
				seamLoop = seamLoop + 1
			end
		end
	end

	-- Return the calculated value
	return returnVal

end

-- ********************************************************************************** --
-- Determines if a particular block is a chest. Returns false if it is not a chest
-- or chests are not being detected
-- ********************************************************************************** --
function isChestBlock(compareFn)

	-- Check the block in the appropriate direction to see whether it is a chest. Only
	-- do this if we are looking for chests
	local returnVal = false
	if (lookForChests == true) then
		turtle.select(15)
		currentlySelectedSlot = 15
		returnVal = compareFn()
	end

	-- Return the calculated value
	return returnVal

end

-- ********************************************************************************** --
-- Function to calculate the number of non seam blocks in the turtle's inventory. This
-- is all of the blocks at the start of the inventory (before the first empty slot is
-- found
-- ********************************************************************************** --
function determineNoiseBlocksCountCount()
	-- Determine the location of the first empty inventory slot. All items before this represent
	-- noise items.
	local foundFirstBlankInventorySlot = false
	noiseBlocksCount = 1
	while ((noiseBlocksCount < 16) and (foundFirstBlankInventorySlot == false)) do
		if (turtle.getItemCount(noiseBlocksCount) > 0) then
			noiseBlocksCount = noiseBlocksCount + 1
		else
			foundFirstBlankInventorySlot = true
		end
	end
	noiseBlocksCount = noiseBlocksCount - 1

	-- Determine whether a chest was provided, and hence whether we should support
	-- looking for chests
	if (turtle.getItemCount(15) > 0) then
		lookForChests = true
		lastEmptySlot = 14
		miningOffset = 0
		writeMessage("Looking for chests...", messageLevel.DEBUG)
	else
		lastEmptySlot = 15
		miningOffset = 1
		writeMessage("Ignoring chests...", messageLevel.DEBUG)
	end
end

-- ********************************************************************************** --
-- Creates a quarry mining out only ores and leaving behind any noise blocks
-- ********************************************************************************** --
function createQuarry()

	-- Determine the top mining layer layer. The turtle mines in layers of 3, and the bottom layer
	-- is the layer directly above bedrock.
	--
	-- The actual layer that the turtle operates in is the middle of these three layers,
	-- so determine the top layer
	local topMiningLayer = startHeight + ((bottomLayer - startHeight - 2) % 3) - 1 + miningOffset

	-- If the top layer is up, then ignore it and move to the next layer
	if (topMiningLayer > currY) then
		topMiningLayer = topMiningLayer - 3
	end

	local startedLayerToRight = true -- Only used where the quarry is of an odd width

	-- Loop over each mining row
	local miningLevel
	for miningLevel = (bottomLayer + miningOffset), topMiningLayer, 3 do
		writeMessage("Mining Layer: "..miningLevel, messageLevel.INFO)
		haveBeenAtZeroZeroOnLayer = false

		-- While the initial shaft is being dug out, set the level to return to in order to unload
		-- to the just take the turtle straight back up
		if (miningLevel == (bottomLayer + miningOffset)) then
			levelToReturnTo = startHeight
		end

		-- Move to the correct level to start mining
		if (currY > miningLevel) then
			while (currY > miningLevel) do
				turtleDown()
			end
		elseif (currY < miningLevel) then
			while (currY < miningLevel) do
				turtleUp()
			end
		end

		-- Am now mining the levels (update the mining state to reflect that fact)
		currMiningState = miningState.LAYER

		-- Set the layer to return via when returning to the surface as the one below the currently
		-- mined one
		if (miningLevel == (bottomLayer + miningOffset)) then
			levelToReturnTo = (bottomLayer + miningOffset)
		else
			levelToReturnTo = miningLevel - 3
		end

		-- Move turtle into the correct orientation to start mining (if this is the
		-- first row to be mined, then don't need to turn, otherwise turn towards the next
		-- mining section)

		writeMessage("Mining Level: "..miningLevel..", Bottom Layer: "..bottomLayer..", Mining Offset: "..miningOffset, messageLevel.DEBUG)

		if (miningLevel > (bottomLayer + miningOffset)) then
			-- Turn towards the next mining layer
			if (quarryWidth % 2 == 0) then
				-- An even width quarry, always turn right
				turtleTurn(direction.RIGHT)
			else
				-- Turn the opposite direction to that which we turned before
				if (startedLayerToRight == true) then
					turtleTurn(direction.LEFT)
					startedLayerToRight = false
				else
					turtleTurn(direction.RIGHT)
					startedLayerToRight = true
				end
			end
		end

		local mineRows
		local onNearSideOfQuarry = true
		local diggingAway = true
		for mineRows = 1, quarryWidth do

			-- If this is not the first row, then get into position to mine the next row
			if ((mineRows == 1) and (lookForChests == false)) then
				-- Not looking for chests, check the block below for being an ore. Only do this
				-- if we're not looking for chests since the program doesn't support chests in
				-- bedrock
				if (isNoiseBlock(turtle.compareDown) == false) then
					turtle.digDown()
					ensureInventorySpace()
				end
			elseif (mineRows > 1) then
				-- Move into position for mining the next row
				if (onNearSideOfQuarry == diggingAway) then
					if (startedLayerToRight == true) then
						turtleTurn(direction.LEFT)
					else
						turtleTurn(direction.RIGHT)
					end
				else
					if (startedLayerToRight == true) then
						turtleTurn(direction.RIGHT)
					else
						turtleTurn(direction.LEFT)
					end
				end

				turtleForward()

				-- Before making the final turn, check the block below. Do this
				-- now because if it is a chest, then we want to back up and
				-- approach it from the side (so that we don't lose items if we
				-- have to return to the start through it).
				--
				-- This is the point at which it is safe to back up without moving
				-- out of the quarry area (unless at bedrock in which case don't bother
				-- as we'll be digging down anyway)
				if (miningLevel ~= bottomLayer) then
					if (isNoiseBlock(turtle.compareDown) == false) then
						-- If we are not looking for chests, then just dig it (it takes
						-- less time to try to dig and fail as it does to do detect and
						-- only dig if there is a block there)
						if (lookForChests == false) then
							turtle.digDown()
							ensureInventorySpace()
						elseif (turtle.detectDown() == true) then
							if (isChestBlock(turtle.compareDown) == true) then
								-- There is a chest block below. Move back and approach
								-- from the side to ensure that we don't need to return to
								-- start through the chest itself (potentially losing items)
								turtleBack()
								turtleDown()
								currMiningState = miningState.EMPTYCHESTDOWN
								emptyChest(turtle.suck)
								currMiningState = miningState.LAYER
								turtleUp()
								turtleForward()
								turtle.digDown()
								ensureInventorySpace()
							else
								turtle.digDown()
								ensureInventorySpace()
							end
						end
					end
				end

				-- Move into final position for mining the next row
				if (onNearSideOfQuarry == diggingAway) then
					if (startedLayerToRight == true) then
						turtleTurn(direction.LEFT)
					else
						turtleTurn(direction.RIGHT)
					end
				else
					if (startedLayerToRight == true) then
						turtleTurn(direction.RIGHT)
					else
						turtleTurn(direction.LEFT)
					end
				end
			end

			-- Dig to the other side of the quarry
			local blocksMined
			for blocksMined = 0, (quarryWidth - 1) do
				if (blocksMined > 0) then
					-- Only move forward if this is not the first space
					turtleForward()
				end

				-- If the current block is (0,0), then record the fact that the
				-- turtle has been through this block and what it's orientation was and update the layer
				-- that it should return via to get back to the surface (it no longer needs to go down
				-- a level to prevent losing ores).
				if ((currX == 0) and (currZ == 0)) then
					-- Am at (0, 0). Remember this, and what direction I was facing so that the quickest route
					-- to the surface can be taken
					levelToReturnTo = miningLevel
					haveBeenAtZeroZeroOnLayer = true
					orientationAtZeroZero = currOrient
				end

				-- If currently at bedrock, just move down until the turtle can't go any
				-- further. This allows the blocks within the bedrock to be mined
				if (miningLevel == bottomLayer) then
					-- Temporarily turn off looking for chests to increase bedrock mining speed (this
					-- means that the program doesn't support chests below level 5 - but I think
					-- they they don't exist anyway)
					local lookForChestsPrev = lookForChests
					lookForChests = false

					-- Manually set the flag to determine whether the turtle should try to move first or
					-- dig first. At bedrock, is very rarely any space

					-- Just above bedrock layer, dig down until can't dig any lower, and then
					-- come back up. This replicates how the quarry functions
					lastMoveNeededDig = true
					local moveDownSuccess = turtleDown()
					while (moveDownSuccess == true) do
						moveDownSuccess = turtleDown()
					end

					-- Know that we are moving back up through air, therefore set the flag to force the
					-- turtle to try moving first
					lastMoveNeededDig = false

					-- Have now hit bedrock, move back to the mining layer
					while (currY < bottomLayer) do
						turtleUp()
					end

					-- Now back at the level above bedrock, again reset the flag to tell the turtle to
					-- try digging again (because it is rare to find air at bedrock level)
					lastMoveNeededDig = false

					-- Reset the look for chests value
					lookForChests = lookForChestsPrev
				elseif ((blocksMined > 0) and ((currX ~= 0) or (currZ ~= 0))) then
					-- This isn't the first block of the row, nor are we at (0, 0) so we need to check the
					-- block below

					-- Check the block down for being a noise block (don't need to check the first
					-- block as it has already been checked in the outer loop)
					if (isNoiseBlock(turtle.compareDown) == false) then
						-- If we are not looking for chests, then just dig it (it takes
						-- less time to try to dig and fail as it does to do detect and
						-- only dig if there is a block there)
						if (lookForChests == false) then
							turtle.digDown()
							ensureInventorySpace()
						elseif (turtle.detectDown() == true) then
							if (isChestBlock(turtle.compareDown) == true) then
								-- There is a chest block below. Move back and approach
								-- from the side to ensure that we don't need to return to
								-- start through the chest itself (potentially losing items)
								turtleBack()
								currMiningState = miningState.EMPTYCHESTDOWN
								turtleDown()
								emptyChest(turtle.suck)
								currMiningState = miningState.LAYER
								turtleUp()
								turtleForward()
								turtle.digDown()
								ensureInventorySpace()
							else
								turtle.digDown()
								ensureInventorySpace()
							end
						end
					end
				end

				-- Check the block above for ores (if we're not a (0, 0) in which case
				-- we know it's air)
				if ((currX ~= 0) or (currZ ~= 0)) then
					if (isNoiseBlock(turtle.compareUp) == false) then
						-- If we are not looking for chests, then just dig it (it takes
						-- less time to try to dig and fail as it does to do detect and
						-- only dig if there is a block there)
						if (lookForChests == false) then
							turtle.digUp()
							ensureInventorySpace()
						elseif (turtle.detectUp() == true) then
							-- Determine if it is a chest before digging it
							if (isChestBlock(turtle.compareUp) == true) then
								-- There is a chest block above. Empty it before digging it
								emptyChest(turtle.suckUp)
								turtle.digUp()
								ensureInventorySpace()
							else
								turtle.digUp()
								ensureInventorySpace()
							end
						end
					end
				end
			end

			-- Am now at the other side of the quarry
			onNearSideOfQuarry = not onNearSideOfQuarry
		end

		-- If we were digging away from the starting point, will be digging
		-- back towards it on the next layer
		diggingAway = not diggingAway
	end

	-- Return to the start
	returnToStartAndUnload(false)

	-- Face forward
	turtleSetOrientation(direction.FORWARD)
end

-- ********************************************************************************** --
-- Reads the next number from a given file
-- ********************************************************************************** --
function readNumber(inputFile)

	local returnVal
	local nextLine = inputFile.readLine()
	if (nextLine ~= nil) then
		returnVal = tonumber(nextLine)
	end

	return returnVal
end

-- ********************************************************************************** --
-- Startup function to support resuming mining turtle
-- ********************************************************************************** --
function isResume()

	local returnVal = false

	-- Try to open the resume file
	local resumeFile = fs.open(startupParamsFile, "r")
	if (resumeFile == nil) then
		-- No resume file (presume that we are not supporting it)
		supportResume = false
	else
		writeMessage("Found startup params file", messageLevel.DEBUG)

		-- Read in the startup params
		quarryWidth = readNumber(resumeFile)
		startHeight = readNumber(resumeFile)
		noiseBlocksCount = readNumber(resumeFile)
		lastEmptySlot = readNumber(resumeFile)
		resumeFile.close()

		-- If the parameters were successfully read, then set the resuming flag to true
		if ((quarryWidth ~= nil) and (startHeight ~= nil) and (noiseBlocksCount ~= nil) and (lastEmptySlot ~= nil)) then

			resuming = true
			writeMessage("Read params", messageLevel.DEBUG)

			-- Determine the look for chest and mining offset
			if (lastEmptySlot == 14) then
				lookForChests = true
				miningOffset = 0
			else
				lookForChests = false
				miningOffset = 1
			end

			-- Get the turtle resume location
			resumeFile = fs.open(oreQuarryLocation, "r")
			if (resumeFile ~= nil) then

				resumeMiningState = readNumber(resumeFile)
				resumeX = readNumber(resumeFile)
				resumeY = readNumber(resumeFile)
				resumeZ = readNumber(resumeFile)
				resumeOrient = readNumber(resumeFile)
				resumeFile.close()

				-- Ensure that the resume location has been found
				if ((resumeMiningState ~= nil) and (resumeX ~= nil) and (resumeY ~= nil) and (resumeZ ~= nil) and (resumeOrient ~= nil)) then
					returnVal = true
					local emptiedInventory = false

					-- Perform any mining state specific startup
					if (resumeMiningState == miningState.EMPTYINVENTORY) then
						-- Am mid way through an empty inventory cycle. Complete it before
						-- starting the main Quarry function
						returnToStartAndUnload(true)
						resuming = true

						-- Continue from the current position
						resumeX = currX
						resumeY = currY
						levelToReturnTo = resumeY
						resumeZ = currZ
						resumeOrient = currOrient

						writeMessage("Resuming with state of "..currMiningState, messageLevel.DEBUG)
						resumeMiningState = currMiningState
						emptiedInventory = true
					end

					-- If was emptying a chest when the program stopped, then move back
					-- to a point which the Quarry
					if (resumeMiningState == miningState.EMPTYCHESTDOWN) then

						-- Set the current X, Y, Z and orientation to the true position that
						-- the turtle is at
						if (emptiedInventory == false) then
							currX = resumeX
							currY = resumeY
							currZ = resumeZ
							currOrient = resumeOrient
						end

						-- Set the mining state as layer, assume haven't been through zero
						-- zero and set the level to return to as the one below the current one
						currMiningState = miningState.LAYER
						levelToReturnTo = currY - 2
						haveBeenAtZeroZeroOnLayer = false

						-- Temporarily disable resuming (so that the new location is written to the file
						-- in case the program stops again)
						resuming = false
						turtleUp()
						resuming = true

						resumeY = currY
						resumeMiningState = miningState.LAYER
					end
				end
			end
		end

		if (returnVal == false) then
			writeMessage("Failed to resume", messageLevel.ERROR)
		end
	end

	return returnVal
end

-- ********************************************************************************** --
-- Main Function
-- ********************************************************************************** --
-- Process the input arguments - storing them to global variables
local args = { ... }
local paramsOK = true

-- Detect whether this is a wireless turtle, and if so, open the modem
local peripheralConnected = peripheral.getType("right")
if (peripheralConnected == "modem") then
	isWirelessTurtle = true
end

-- If a wireless turtle, open the modem
if (isWirelessTurtle == true) then
	turtleId = os.getComputerLabel()
	rednet.open("right")
end

-- give an empty turtleID if it's nil
if (turtleId == nil ) then
	turtleId = " "
end

if (#args == 0) then
	-- Is this a resume?
	if (isResume() == false) then
		paramsOK = false
	end
elseif (#args == 1) then
	quarryWidth = tonumber(args[1])
	local x, y, z = gps.locate(5)
	startHeight = y
	if (startHeight == nil) then
		writeMessage("Can't locate GPS", messageLevel.FATAL)
		paramsOK = false
	end
elseif (#args == 2) then
	if (args[2] == "/r") then
		quarryWidth = tonumber(args[1])
		supportResume = false
	else
		quarryWidth = tonumber(args[1])
		startHeight = tonumber(args[2])
	end
elseif (#args == 3) then
	quarryWidth = tonumber(args[1])
	startHeight = tonumber(args[2])
	if (args[3] == "/r") then
		supportResume = false
	else
		paramsOK = false
	end
end

if ((paramsOK == false) and (resuming == false)) then
	writeMessage("Usage: "..shell.getRunningProgram().." <diameter> [turtleY] [/r]", messageLevel.FATAL)
	paramsOK = false
end

if (paramsOK == true) then
	if ((startHeight < bottomLayer+1) or (startHeight > 128)) then
		writeMessage("turtleY must be between 3 and 128", messageLevel.FATAL)
		paramsOK = false
	end

	if ((quarryWidth < 2) or (quarryWidth > 64)) then
		writeMessage("diameter must be between 2 and 64", messageLevel.FATAL)
		paramsOK = false
	end
end

if (paramsOK == true) then
	if (resuming == true) then
		writeMessage("Resuming Ore Quarry...", messageLevel.INFO)
	else
		writeMessage("--------------------------------------------------------", messageLevel.INFO)
		writeMessage("** Ore Quarry v0.71 by AustinKK (Modified by WillisS) **", messageLevel.INFO)
		writeMessage("--------------------------------------------------------", messageLevel.INFO)
	end

	-- Set the turtle's starting position
	currX = 0
	currY = startHeight
	currZ = 0
	currOrient = direction.FORWARD

	-- Calculate which blocks in the inventory signify noise blocks
	if (resuming == false) then
		determineNoiseBlocksCountCount()
	end

	if ((noiseBlocksCount == 0) or (noiseBlocksCount > 13)) then
		writeMessage("No noise blocks have been been added. Please place blocks that the turtle should not mine (e.g. Stone, Dirt, Gravel etc.) in the first few slots of the turtle\'s inventory. The first empty slot signifies the end of the noise blocks.", messageLevel.FATAL)
	else
		-- If we are supporting resume (and are not currently in the process of resuming)
		-- then store startup parameters in appropriate files
		if ((supportResume == true) and (resuming == false)) then
			-- Write the startup parameters to  file
			local outputFile = io.open(startupParamsFile, "w")
			outputFile:write(quarryWidth)
			outputFile:write("\n")
			outputFile:write(startHeight)
			outputFile:write("\n")
			outputFile:write(noiseBlocksCount)
			outputFile:write("\n")
			outputFile:write(lastEmptySlot)
			outputFile:write("\n")
			outputFile:close()

			-- Setup the startup file

			-- Take a backup of the current startup file
			if (fs.exists("startup") == true) then
				fs.copy("startup", startupBackup)
				outputFile = io.open("startup", "a")
			else
				outputFile = io.open("startup", "w")
			end

			-- Write an info message so that people know how to get out of auto-resume
			outputFile:write("\nprint(\"Running auto-restart...\")\n")
			outputFile:write("print(\"If you want to stop auto-resume and restore original state:\")\n")
			outputFile:write("print(\"1) Hold Ctrl-T until the program terminates\")\n")
			outputFile:write("print(\"2) Type \\\"rm startup\\\" (without quotes) and hit Enter\")\n")
			outputFile:write("print(\"\")\n\n")

			-- Write the code required to restart the turtle
			outputFile:write("shell.run(\"")
			outputFile:write(shell.getRunningProgram())
			outputFile:write("\")\n")
			outputFile:close()

		end

		-- Create a Quarry
		turtle.select(1)
		currentlySelectedSlot = 1
		createQuarry()

		-- Restore the file system to its original configuration
		if (supportResume == true) then
			fs.delete("startup")
			if (fs.exists(startupBackup) == true) then
				fs.move(startupBackup, "startup")
			end

			if (fs.exists(startupParamsFile) == true) then
				fs.delete(startupParamsFile)
			end

			if (fs.exists(oreQuarryLocation) == true) then
				fs.delete(oreQuarryLocation)
			end

			if (fs.exists(returnToStartFile) == true) then
				fs.delete(returnToStartFile)
			end
		end
	end
end