OreQuarry Upgrade

-- ********************************************************************************** --
-- **                                                                              ** --
-- **   Minecraft Mining Turtle Ore Quarry v0.6c by AustinKK, Aeolun               ** --
-- **   ---------------------------------------------------                        ** --
-- **                                                                              ** --
-- **   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                            ** --
-- **    14th Jan 2013: [v0.6a] Added waiting at starting location again           ** --
-- **    17th Jan 2013: [v0.6b] Added possibility of cancelling the resume         ** --
-- **    17th Jan 2013: [v0.6c] Added possibility of not starting at the bottom    ** --
-- **                                                                              ** --
-- ********************************************************************************** --

-- 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.DEBUG
local messageOutputFileName = "log.txt"
local fuelLevelToRefuelAt = 300
local refuelItemsToUseWhenRefuelling = 63
local emergencyFuelToRetain = 3 -- Turtle will return to start once it reaches the emergency fuel levels
local fuelLevelToStartMiningAt = 25000 -- Turtle will not leave start unless it has at least this amount of fuel (not fuel items, but fuel level)
local maximumGravelStackSupported = 25 -- The number of stacked gravel or sand blocks supported
local noiseBlocksCount
local bottomLayer = 5 -- The y co-ords of the layer immediately above bedrock
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 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

-- 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 (turtleId == nil) then
            rednet.broadcast(message)
        else
            -- Broadcast the message (prefixed with the turtle's id)
            rednet.broadcast("[".. turtleId.."] "..message)
        end

        if (messageOutputFileName ~= nil) then
            -- Open file, write message and close file (flush doesn't seem to work!)
            local outputFile = io.open(messageOutputFileName, "a")
            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 items!", messageLevel.FATAL)
                if returningToStart == false then
                    returnToStartAndUnload(true)
                end
            elseif (fuelItems == 1) then
                writeMessage("Out of fuel items!", messageLevel.ERROR)
                turtle.refuel()
                if returningToStart == false then
                    returnToStartAndUnload(true)
                end
            elseif (fuelItems <= (emergencyFuelToRetain + 1)) then
                writeMessage("Consuming emergency fuel supply. "..(fuelItems - 2).." emergency fuel items remain", messageLevel.WARNING)
                turtle.refuel(1)
                if returningToStart == false 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 restoreResume()
    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

function refuelAtStart()
    -- While we are here, refill the fuel items if there is capacity
    if (turtle.getItemCount(16) < 64) then
        writeMessage("Refueling", messageLevel.INFO);
        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)
        local currFuelLevel = turtle.getFuelLevel();
        turtle.suck()
        while ((currFuelItems ~= turtle.getItemCount(16)) and (turtle.getItemCount(16) < 64)) do
            currFuelItems = turtle.getItemCount(16)
            turtle.suck()
        end

        if currFuelLevel < fuelLevelToStartMiningAt then
            -- Turtle doesn't have enough fuel to even start mining
            writeMessage("Turtle cannot retrieve enough fuel. Waiting until we have at least "..fuelLevelToStartMiningAt.." fuel", messageLevel.WARNING)
            turtle.suck()
            turtle.refuel();
            while currFuelLevel < fuelLevelToStartMiningAt do
                currFuelLevel = turtle.getFuelLevel();
                writeMessage("Fuel level at "..currFuelLevel, messageLevel.INFO)
                turtle.suck()
                turtle.refuel();
                os.sleep(1)
            end
            writeMessage("Minimum fuel reached, starting", messageLevel.INFO)
        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
            turtle.select(slotLoop) -- Don't bother updating selected slot variable as it will set later in this function
            turtle.drop()
            slotLoop = slotLoop + 1
        end

        turtleSetOrientation(direction.FORWARD)
    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)
                turtle.drop(turtle.getItemCount(slotLoop) - 1)
            else
                -- Not a noise block, drop all of the items in this slot
                writeMessage("Dropping (all) from slot "..slotLoop.." ["..turtle.getItemCount(slotLoop).."]", messageLevel.DEBUG)
                turtle.drop()
            end

            slotLoop = slotLoop + 1
        end

        refuelAtStart()

        -- 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()
    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()
    -- Before doing anything, check whether there is any extra fuel for us
    if resuming == false then
        refuelAtStart()
    end

    -- 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
        function waitForABit()
            writeMessage("Press C to cancel resume", messageLevel.INFO)
            writeMessage("Continuing in 5 seconds...", messageLevel.INFO)
            os.sleep(5)
        end
        function ifKeyPress()
            while true do
                local event, param1 = os.pullEvent ("char") -- limit os.pullEvent to the char event
                if param1 == "c" then -- if the returned value was 'c'
                    return
                end
            end
        end
        cancel = parallel.waitForAny(waitForABit, ifKeyPress)
        writeMessage(cancel, messageLevel.INFO)
        if cancel == 2 then
            writeMessage("Resume will be cancelled. Rebooting...", messageLevel.INFO)
            resumeFile.close()
            restoreResume()
            sleep(0.5)
            os.reboot()
        end


        writeMessage("Found startup params file", messageLevel.DEBUG)

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

turtleId = os.getComputerLabel()
rednet.open("right")

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
        bottomLayer = tonumber(args[3])
    end
end

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

if (paramsOK == true) then
    if ((startHeight < 6) or (startHeight > 128)) then
        writeMessage("turtleY must be between 6 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

    if ((bottomLayer > startHeight) or (bottomLayer < 5)) then
        writeMessage("bottomLayer must be between 5 and turtleY", messageLevel.FATAL)
        paramsOK = false
    end
end

if (paramsOK == true) then
    writeMessage("----------------------------------", messageLevel.INFO)
    writeMessage("** Ore Quarry v0.6c by AustinKK **", messageLevel.INFO)
    writeMessage("----------------------------------", messageLevel.INFO)
    if (resuming == true) then
        writeMessage("Resuming...", 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:write(bottomLayer)
            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)
            end

            -- Write a new startup file to resume the turtle
            outputFile = io.open("startup", "a")
            outputFile:write("\nshell.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
            restoreResume()
        end
    end
end