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 -- ********************************************************************************** --
 -- **                                                                              ** --
 -- **   Minecraft Mining Turtle Ore Quarry v0.7 by AustinKK                        ** --
 -- **   ---------------------------------------------------                        ** --
 -- **                                                                              ** --
 -- **   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 v1.52                       ** --
 -- **                                                                              ** --
 -- ********************************************************************************** --
 
 -- 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 = 5
 local refuelItemsToUseWhenRefuelling = 63
 local emergencyFuelToRetain = 0
 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 returningToStart = true
 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
 
 -- 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 = 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!", 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)
       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()
   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
 isWirelessTurtle = peripheral.isPresent("right")
 if (isWirelessTurtle == true) then
   turtleId = os.getComputerLabel()
   rednet.open("right")
 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 < 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
 end
 
 if (paramsOK == true) then
   writeMessage("---------------------------------", messageLevel.INFO)
   writeMessage("** Ore Quarry v0.7 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: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
       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