GCodes.cpp

/****************************************************************************************************

RepRapFirmware - G Codes

This class interprets G Codes from one or more sources, and calls the functions in Move, Heat etc
that drive the machine to do what the G Codes command.

Most of the functions in here are designed not to wait, and they return a boolean.  When you want them to do
something, you call them.  If they return false, the machine can't do what you want yet.  So you go away
and do something else.  Then you try again.  If they return true, the thing you wanted done has been done.

-----------------------------------------------------------------------------------------------------

Version 0.1

13 February 2013

Adrian Bowyer
RepRap Professional Ltd
http://reprappro.com

Licence: GPL

****************************************************************************************************/

#include "RepRapFirmware.h"

GCodes::GCodes(Platform* p, Webserver* w)
{
  active = false;
  platform = p;
  webserver = w;
  webGCode = new GCodeBuffer(platform, "web: ");
  fileGCode = new GCodeBuffer(platform, "file: ");
  serialGCode = new GCodeBuffer(platform, "serial: ");
  cannedCycleGCode = new GCodeBuffer(platform, "macro: ");
}

void GCodes::Exit()
{
   platform->Message(BOTH_MESSAGE, "GCodes class exited.\n");
   active = false;
}

void GCodes::Init()
{
  webGCode->Init();
  fileGCode->Init();
  serialGCode->Init();
  cannedCycleGCode->Init();
  webGCode->SetFinished(true);
  fileGCode->SetFinished(true);
  serialGCode->SetFinished(true);
  cannedCycleGCode->SetFinished(true);
  moveAvailable = false;
  drivesRelative = true;
  axesRelative = false;
  checkEndStops = false;
  gCodeLetters = GCODE_LETTERS;
  distanceScale = 1.0;
  for(int8_t i = 0; i < DRIVES - AXES; i++)
    lastPos[i] = 0.0;
  fileBeingPrinted = NULL;
  fileToPrint = NULL;
  fileBeingWritten = NULL;
  configFile = NULL;
  doingCannedCycleFile = false;
  eofString = EOF_STRING;
  eofStringCounter = 0;
  eofStringLength = strlen(eofString);
  homeX = false;
  homeY = false;
  homeZ = false;
  homeAxisMoveCount = 0;
  offSetSet = false;
  dwellWaiting = false;
  stackPointer = 0;
  zProbesSet = false;
  probeCount = 0;
  cannedCycleMoveCount = 0;
  cannedCycleMoveQueued = false;
  limitAxes = true;
  axisIsHomed[X_AXIS] = axisIsHomed[Y_AXIS] = axisIsHomed[Z_AXIS] = false;
  toolChangeSequence = 0;
  active = true;
  longWait = platform->Time();
  dwellTime = longWait;
}

void GCodes::DoFilePrint(GCodeBuffer* gb)
{
	char b;

	if(fileBeingPrinted != NULL)
	{
		if(fileBeingPrinted->Read(b))
		{
			if(gb->Put(b))
				gb->SetFinished(ActOnGcode(gb));
		} else
		{
			if(gb->Put('\n')) // In case there wasn't one ending the file
				gb->SetFinished(ActOnGcode(gb));
			fileBeingPrinted->Close();
			fileBeingPrinted = NULL;
		}
	}
}

void GCodes::Spin()
{
  if(!active)
    return;
    
  // Check each of the sources of G Codes (web, serial, and file) to
  // see if what they are doing has been done.  If it hasn't, return without
  // looking at anything else.
  //
  // Note the order establishes a priority: web first, then serial, and file
  // last.  If file weren't last, then the others would never get a look in when
  // a file was being printed.

  if(!webGCode->Finished())
  {
    webGCode->SetFinished(ActOnGcode(webGCode));
    platform->ClassReport("GCodes", longWait);
    return;
  }
  
  if(!serialGCode->Finished())
  {
    serialGCode->SetFinished(ActOnGcode(serialGCode));
    platform->ClassReport("GCodes", longWait);
    return;
  }  

  if(!fileGCode->Finished())
  {
    fileGCode->SetFinished(ActOnGcode(fileGCode));
    platform->ClassReport("GCodes", longWait);
    return;
  }

  // Now check if a G Code byte is available from each of the sources
  // in the same order for the same reason.

  if(webserver->GCodeAvailable())
  {
	  int8_t i = 0;
	  do
	  {
		  char b = webserver->ReadGCode();
		  if(webGCode->Put(b))
		  {
			  // we have a complete gcode
			  if(webGCode->WritingFileDirectory() != NULL)
			  {
				  WriteGCodeToFile(webGCode);
			  }
			  else
			  {
				  webGCode->SetFinished(ActOnGcode(webGCode));
			  }
			  break;	// stop after receiving a complete gcode in case we haven't finished processing it
		  }
		  ++i;
	  } while ( i < 16 && webserver->GCodeAvailable());
	  platform->ClassReport("GCodes", longWait);
	  return;
  }
  
  // Now the serial interface.  First check the special case of our
  // uploading the reprap.htm file

  if(serialGCode->WritingFileDirectory() == platform->GetWebDir())
  {
	  if(platform->GetLine()->Status() & byteAvailable)
	  {
		  char b;
		  platform->GetLine()->Read(b);
		  WriteHTMLToFile(b, serialGCode);
	  }
  } else
  {
	  // Otherwise just deal in general with incoming bytes from the serial interface

	  if(platform->GetLine()->Status() & byteAvailable)
	  {
		  // Read several bytes instead of just one. This approximately doubles the speed of file uploading.
		  int8_t i = 0;
		  do
		  {
			  char b;
			  platform->GetLine()->Read(b);
			  if(serialGCode->Put(b))	// add char to buffer and test whether the gcode is complete
			  {
				  // we have a complete gcode
				  if(serialGCode->WritingFileDirectory() != NULL)
				  {
					  WriteGCodeToFile(serialGCode);
				  }
				  else
				  {
					  serialGCode->SetFinished(ActOnGcode(serialGCode));
				  }
				  break;	// stop after receiving a complete gcode in case we haven't finished processing it
			  }
			  ++i;
		  } while (i < 16 && (platform->GetLine()->Status() & byteAvailable));
		  platform->ClassReport("GCodes", longWait);
		  return;
	  }
  }

  DoFilePrint(fileGCode);

  platform->ClassReport("GCodes", longWait);
}

void GCodes::Diagnostics() 
{
  platform->Message(BOTH_MESSAGE, "GCodes Diagnostics:\n");
}

// The wait till everything's done function.  If you need the machine to
// be idle before you do something (for example homeing an axis, or shutting down) call this
// until it returns true.  As a side-effect it loads moveBuffer with the last
// position and feedrate for you.

bool GCodes::AllMovesAreFinishedAndMoveBufferIsLoaded()
{
  // Last one gone?
  
  if(moveAvailable)
    return false;
  
  // Wait for all the queued moves to stop so we get the actual last position and feedrate
      
  if(!reprap.GetMove()->AllMovesAreFinished())
    return false;
  reprap.GetMove()->ResumeMoving();
    
  // Load the last position; If Move can't accept more, return false - should never happen
  
  if(!reprap.GetMove()->GetCurrentUserPosition(moveBuffer))
    return false;

  return true;  
}

// Save (some of) the state of the machine for recovery in the future.
// Call repeatedly till it returns true.

bool GCodes::Push()
{
  if(stackPointer >= STACK)
  {
    platform->Message(BOTH_ERROR_MESSAGE, "Push(): stack overflow!\n");
    return true;
  }
  
  if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
    return false;
  
  drivesRelativeStack[stackPointer] = drivesRelative;
  axesRelativeStack[stackPointer] = axesRelative;
  feedrateStack[stackPointer] = moveBuffer[DRIVES];
  fileStack[stackPointer] = fileBeingPrinted;
  stackPointer++;
  platform->PushMessageIndent();
  return true;
}

// Recover a saved state.  Call repeatedly till it returns true.

bool GCodes::Pop()
{
  if(stackPointer <= 0)
  {
    platform->Message(BOTH_ERROR_MESSAGE, "Pop(): stack underflow!\n");
    return true;  
  }
  
  if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
    return false;
    
  stackPointer--;
  drivesRelative = drivesRelativeStack[stackPointer];
  axesRelative = axesRelativeStack[stackPointer];
  fileBeingPrinted = fileStack[stackPointer];
  platform->PopMessageIndent();
  // Remember for next time if we have just been switched
  // to absolute drive moves
  
  for(int8_t i = AXES; i < DRIVES; i++)
    lastPos[i - AXES] = moveBuffer[i];
  
  // Do a null move to set the correct feedrate
  
  moveBuffer[DRIVES] = feedrateStack[stackPointer];
  
  checkEndStops = false;
  moveAvailable = true;
  return true;
}

// Move expects all axis movements to be absolute, and all
// extruder drive moves to be relative.  This function serves that.
// If applyLimits is true and we have homed the relevant axes, then we don't allow movement beyond the bed.

bool GCodes::LoadMoveBufferFromGCode(GCodeBuffer *gb, bool doingG92, bool applyLimits)
{
	// First do extrusion, and check, if we are extruding, that we have a tool to extrude with

	Tool* tool = reprap.GetCurrentTool();
	if(gb->Seen(EXTRUDE_LETTER))
	{
		if(tool == NULL)
		{
			platform->Message(BOTH_ERROR_MESSAGE, "Attempting to extrude with no tool selected.\n");
			return false;
		}
		float eMovement[DRIVES-AXES];
		int eMoveCount = tool->DriveCount();
		gb->GetFloatArray(eMovement, eMoveCount);
		if(tool->DriveCount() != eMoveCount)
		{
			snprintf(scratchString, STRING_LENGTH, "Wrong number of extruder drives for the selected tool: %s\n", gb->Buffer());
			platform->Message(HOST_MESSAGE, scratchString);
			return false;
		}

		// Zero every extruder drive as some drives may not be changed

		for(int8_t drive = AXES; drive < DRIVES; drive++)
				moveBuffer[drive] = 0.0;

		// Set the drive values for this tool.

		for(int8_t eDrive = 0; eDrive < eMoveCount; eDrive++)
		{
			int8_t drive = tool->Drive(eDrive);
			if(drivesRelative || doingG92)
			{
				moveBuffer[drive + AXES] = eMovement[eDrive]*distanceScale; //Absolute
				if(doingG92)
					lastPos[drive] = moveBuffer[drive + AXES];
			} else
			{
				float absE = eMovement[eDrive]*distanceScale;
				moveBuffer[drive + AXES] = absE - lastPos[drive];
				lastPos[drive] = absE;
			}
		}
	}

	// Now the movement axes

	for(uint8_t axis = 0; axis < AXES; axis++)
	{
		if(gb->Seen(gCodeLetters[axis]))
		{
			float moveArg = gb->GetFValue()*distanceScale;
			if (axesRelative && !doingG92)
			{
				moveArg += moveBuffer[axis];
			}
			if (applyLimits && axis < 2 && axisIsHomed[axis] && !doingG92)	// limit X & Y moves unless doing G92.  FIXME: No Z for the moment as we often need to move -ve to set the origin
			{
				if (moveArg < 0.0)
				{
					moveArg = 0.0;
				} else if (moveArg > platform->AxisLength(axis))
				{
					moveArg = platform->AxisLength(axis);
				}
			}
			moveBuffer[axis] = moveArg;
			if (doingG92)
			{
				axisIsHomed[axis] = true;		// doing a G92 is equivalent to homing the axis.  FIXME: No it's not if the coordinate specified wasn't 0.
			}
		}
	}

	// Deal with feedrate

	if(gb->Seen(FEEDRATE_LETTER))
		moveBuffer[DRIVES] = gb->GetFValue()*distanceScale*0.016666667; // G Code feedrates are in mm/minute; we need mm/sec

	return true;
}



// This function is called for a G Code that makes a move.
// If the Move class can't receive the move (i.e. things have to wait)
// this returns false, otherwise true.

bool GCodes::SetUpMove(GCodeBuffer *gb)
{
  // Last one gone yet?
  
  if(moveAvailable)
    return false;
    
  // Load the last position into moveBuffer; If Move can't accept more, return false

  if(!reprap.GetMove()->GetCurrentUserPosition(moveBuffer))
    return false;

  //check to see if the move is a 'homing' move that endstops are checked on.
  checkEndStops = false;
  if(gb->Seen('S'))
  {
	  if(gb->GetIValue() == 1)
		  checkEndStops = true;
  }

  //loads the movebuffer with either the absolute movement required or the
  //relative movement required
  moveAvailable = LoadMoveBufferFromGCode(gb, false, !checkEndStops && limitAxes);

  return true; 
}

// The Move class calls this function to find what to do next.

bool GCodes::ReadMove(float m[], bool& ce)
{
    if(!moveAvailable)
      return false; 
    for(int8_t i = 0; i <= DRIVES; i++) // 1 more for feedrate
      m[i] = moveBuffer[i];
    ce = checkEndStops;
    moveAvailable = false;
    checkEndStops = false;
    return true;
}


bool GCodes::DoFileCannedCycles(const char* fileName)
{
	// Have we started the file?

	if(!doingCannedCycleFile)
	{
		// No

		if(!Push())
			return false;

		fileBeingPrinted = platform->GetFileStore(platform->GetSysDir(), fileName, false);
		if(fileBeingPrinted == NULL)
		{
			snprintf(scratchString, STRING_LENGTH, "Macro file %s not found.\n ", fileName);
			platform->Message(HOST_MESSAGE, scratchString);
			if(!Pop())
				platform->Message(HOST_MESSAGE, "Cannot pop the stack.\n");
			return true;
		}
		doingCannedCycleFile = true;
		cannedCycleGCode->Init();
		return false;
	}

	// Have we finished the file?

	if(fileBeingPrinted == NULL)
	{
		// Yes

		if(!Pop())
			return false;
		doingCannedCycleFile = false;
		cannedCycleGCode->Init();
		return true;
	}

	// No - Do more of the file

	if(!cannedCycleGCode->Finished())
	{
		cannedCycleGCode->SetFinished(ActOnGcode(cannedCycleGCode));
	    return false;
	}

	DoFilePrint(cannedCycleGCode);

	return false;
}

bool GCodes::FileCannedCyclesReturn()
{
	if(!doingCannedCycleFile)
		return true;

	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
		return false;

	doingCannedCycleFile = false;
	cannedCycleGCode->Init();

	if(fileBeingPrinted != NULL)
		fileBeingPrinted->Close();

	fileBeingPrinted = NULL;
	return true;
}

// To execute any move, call this until it returns true.
// moveToDo[] entries corresponding with false entries in action[] will
// be ignored.  Recall that moveToDo[DRIVES] should contain the feedrate
// you want (if action[DRIVES] is true).

bool GCodes::DoCannedCycleMove(bool ce)
{
	// Is the move already running?

	if(cannedCycleMoveQueued)
	{ // Yes.
		if(!Pop()) // Wait for the move to finish then restore the state
			return false;
		cannedCycleMoveQueued = false;
		return true;
	} else
	{ // No.
		if(!Push()) // Wait for the RepRap to finish whatever it was doing, save it's state, and load moveBuffer[] with the current position.
			return false;
		for(int8_t drive = 0; drive <= DRIVES; drive++)
		{
			if(activeDrive[drive])
				moveBuffer[drive] = moveToDo[drive];
		}
		checkEndStops = ce;
		cannedCycleMoveQueued = true;
		moveAvailable = true;
	}
	return false;
}

// This sets positions.  I.e. it handles G92.

bool GCodes::SetPositions(GCodeBuffer *gb)
{
	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
		return false;

	if(LoadMoveBufferFromGCode(gb, true, false))
	{
		// Transform the position so that e.g. if the user does G92 Z0,
		// the position we report (which gets inverse-transformed) really is Z=0 afterwards
		reprap.GetMove()->Transform(moveBuffer);
		reprap.GetMove()->SetLiveCoordinates(moveBuffer);
		reprap.GetMove()->SetPositions(moveBuffer);
		reprap.GetMove()->SetFeedrate(platform->InstantDv(platform->SlowestDrive()));  // On a G92 we must effectively be stationary
	}

	return true;
}

// Offset the axes by the X, Y, and Z amounts in the M code in gb.  Say the machine is at [10, 20, 30] and
// the offsets specified are [8, 2, -5].  The machine will move to [18, 22, 25] and henceforth consider that point
// to be [10, 20, 30].

bool GCodes::OffsetAxes(GCodeBuffer* gb)
{
	if(!offSetSet)
	{
		if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
		    return false;
		for(int8_t drive = 0; drive <= DRIVES; drive++)
		{
			if(drive < AXES || drive == DRIVES)
			{
				record[drive] = moveBuffer[drive];
				moveToDo[drive] = moveBuffer[drive];
			} else
			{
				record[drive] = 0.0;
				moveToDo[drive] = 0.0;
			}
			activeDrive[drive] = false;
		}

		for(int8_t axis = 0; axis < AXES; axis++)
		{
			if(gb->Seen(gCodeLetters[axis]))
			{
				moveToDo[axis] += gb->GetFValue();
				activeDrive[axis] = true;
			}
		}

		if(gb->Seen(FEEDRATE_LETTER)) // Has the user specified a feedrate?
		{
			moveToDo[DRIVES] = gb->GetFValue();
			activeDrive[DRIVES] = true;
		}

		offSetSet = true;
	}


	if(DoCannedCycleMove(false))
	{
		//LoadMoveBufferFromArray(record);
		for(int drive = 0; drive <= DRIVES; drive++)
			moveBuffer[drive] = record[drive];
		reprap.GetMove()->SetLiveCoordinates(record);  // This doesn't transform record
		reprap.GetMove()->SetPositions(record);        // This does
		offSetSet = false;
		return true;
	}

	return false;
}

// Home one or more of the axes.  Which ones are decided by the
// booleans homeX, homeY and homeZ.
// Returns true if completed, false if needs to be called again.
// 'reply' is only written if there is an error.
// 'error' is false on entry, gets changed to true if there is an error.
bool GCodes::DoHome(char* reply, bool& error)
//pre(reply.upb == STRING_LENGTH)
{
	if(homeX && homeY && homeZ)
	{
		if(DoFileCannedCycles(HOME_ALL_G))
		{
			homeAxisMoveCount = 0;
			homeX = false;
			homeY = false;
			homeZ = false;
			axisIsHomed[X_AXIS] = axisIsHomed[Y_AXIS] = axisIsHomed[Z_AXIS] = true;
			return true;
		}
		return false;
	}

	if(homeX)
	{
		if(DoFileCannedCycles(HOME_X_G))
		{
			homeAxisMoveCount = 0;
			homeX = false;
			axisIsHomed[X_AXIS] = true;
			return NoHome();
		}
		return false;
	}


	if(homeY)
	{
		if(DoFileCannedCycles(HOME_Y_G))
		{
			homeAxisMoveCount = 0;
			homeY = false;
			axisIsHomed[Y_AXIS] = true;
			return NoHome();
		}
		return false;
	}


	if(homeZ)
	{
		//FIXME this check should be optional
		if (!(axisIsHomed[X_AXIS] && axisIsHomed[Y_AXIS]))
		{
			// We can only home Z if X and Y have already been homed. Possibly this should only be if we are using an IR probe.
			strncpy(reply, "Must home X and Y before homing Z", STRING_LENGTH);
			error = true;
			homeZ = false;
			return true;
		}
		if(DoFileCannedCycles(HOME_Z_G))
		{
			homeAxisMoveCount = 0;
			homeZ = false;
			axisIsHomed[Z_AXIS] = true;
			return NoHome();
		}
		return false;
	}

	// Should never get here

	checkEndStops = false;
	moveAvailable = false;
	homeAxisMoveCount = 0;

	return true;
}

// This lifts Z a bit, moves to the probe XY coordinates (obtained by a call to GetProbeCoordinates() ),
// probes the bed height, and records the Z coordinate probed.  If you want to program any general
// internal canned cycle, this shows how to do it.

bool GCodes::DoSingleZProbeAtPoint()
{
	float x, y, z;

	reprap.GetMove()->SetIdentityTransform();  // It doesn't matter if these are called repeatedly

	for(int8_t drive = 0; drive <= DRIVES; drive++)
		activeDrive[drive] = false;

	switch(cannedCycleMoveCount)
	{
	case 0:  // This only does anything on the first move; on all the others Z is already there
		moveToDo[Z_AXIS] = Z_DIVE;
		activeDrive[Z_AXIS] = true;
		moveToDo[DRIVES] = platform->HomeFeedRate(Z_AXIS);
		activeDrive[DRIVES] = true;
		reprap.GetMove()->SetZProbing(false);
		if(DoCannedCycleMove(false))
			cannedCycleMoveCount++;
		return false;

	case 1:
		GetProbeCoordinates(probeCount, moveToDo[X_AXIS], moveToDo[Y_AXIS], moveToDo[Z_AXIS]);
		activeDrive[X_AXIS] = true;
		activeDrive[Y_AXIS] = true;
		// NB - we don't use the Z value
		moveToDo[DRIVES] = platform->HomeFeedRate(X_AXIS);
		activeDrive[DRIVES] = true;
		reprap.GetMove()->SetZProbing(false);
		if(DoCannedCycleMove(false))
			cannedCycleMoveCount++;
		return false;

	case 2:
		moveToDo[Z_AXIS] = -2.0*platform->AxisLength(Z_AXIS);
		activeDrive[Z_AXIS] = true;
		moveToDo[DRIVES] = platform->HomeFeedRate(Z_AXIS);
		activeDrive[DRIVES] = true;
		reprap.GetMove()->SetZProbing(true);
		if(DoCannedCycleMove(true))
		{
			cannedCycleMoveCount++;
			axisIsHomed[Z_AXIS] = true;		// we now home the Z-axis in Move.cpp it is wasn't already
		}
		return false;

	case 3:
		moveToDo[Z_AXIS] = Z_DIVE;
		activeDrive[Z_AXIS] = true;
		moveToDo[DRIVES] = platform->HomeFeedRate(Z_AXIS);
		activeDrive[DRIVES] = true;
		reprap.GetMove()->SetZProbing(false);
		if(DoCannedCycleMove(false))
			cannedCycleMoveCount++;
		return false;

	default:
		cannedCycleMoveCount = 0;
		reprap.GetMove()->SetZBedProbePoint(probeCount, reprap.GetMove()->GetLastProbedZ());
		return true;
	}
}


// This simply moves down till the Z probe/switch is triggered.

bool GCodes::DoSingleZProbe()
{
	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
		return false;

	for(int8_t drive = 0; drive <= DRIVES; drive++)
		activeDrive[drive] = false;

	moveToDo[Z_AXIS] = -1.1*platform->AxisLength(Z_AXIS);
	activeDrive[Z_AXIS] = true;
	moveToDo[DRIVES] = platform->HomeFeedRate(Z_AXIS);
	activeDrive[DRIVES] = true;
	if(DoCannedCycleMove(true))
	{
		cannedCycleMoveCount = 0;
		probeCount = 0;
		axisIsHomed[Z_AXIS] = true;	// we have homed the Z axis
		return true;
	}
	return false;
}

// This sets wherever we are as the probe point P (probePointIndex)
// then probes the bed, or gets all its parameters from the arguments.
// If X or Y are specified, use those; otherwise use the machine's
// coordinates.  If no Z is specified use the machine's coordinates.  If it
// is specified and is greater than SILLY_Z_VALUE (i.e. greater than -9999.0)
// then that value is used.  If it's less than SILLY_Z_VALUE the bed is
// probed and that value is used.

bool GCodes::SetSingleZProbeAtAPosition(GCodeBuffer *gb)
{
	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
		return false;

	if(!gb->Seen('P'))
		return DoSingleZProbe();

	int probePointIndex = gb->GetIValue();

	float x, y, z;
	if(gb->Seen(gCodeLetters[X_AXIS]))
		x = gb->GetFValue();
	else
		x = moveBuffer[X_AXIS];
	if(gb->Seen(gCodeLetters[Y_AXIS]))
		y = gb->GetFValue();
	else
		y = moveBuffer[Y_AXIS];
	if(gb->Seen(gCodeLetters[Z_AXIS]))
		z = gb->GetFValue();
	else
		z = moveBuffer[Z_AXIS];

	probeCount = probePointIndex;
	reprap.GetMove()->SetXBedProbePoint(probeCount, x);
	reprap.GetMove()->SetYBedProbePoint(probeCount, y);

	if(z > SILLY_Z_VALUE)
	{
		reprap.GetMove()->SetZBedProbePoint(probeCount, z);
		reprap.GetMove()->SetZProbing(false); // Not really needed, but let's be safe
		probeCount = 0;
		if(gb->Seen('S'))
		{
			zProbesSet = true;
			reprap.GetMove()->SetProbedBedEquation();
		}
		return true;
	} else
	{
		if(DoSingleZProbeAtPoint())
		{
			probeCount = 0;
			reprap.GetMove()->SetZProbing(false);
			if(gb->Seen('S'))
			{
				zProbesSet = true;
				reprap.GetMove()->SetProbedBedEquation();
			}
			return true;
		}
	}

	return false;
}

// This probes multiple points on the bed (three in a
// triangle or four in the corners), then sets the bed transformation to compensate
// for the bed not quite being the plane Z = 0.

bool GCodes::DoMultipleZProbe()
{
	if(reprap.GetMove()->NumberOfXYProbePoints() < 3)
	{
		platform->Message(HOST_MESSAGE, "Bed probing: there needs to be 3 or more points set.\n");
		return true;
	}

	if(DoSingleZProbeAtPoint())
		probeCount++;
	if(probeCount >= reprap.GetMove()->NumberOfXYProbePoints())
	{
		probeCount = 0;
		zProbesSet = true;
		reprap.GetMove()->SetZProbing(false);
		reprap.GetMove()->SetProbedBedEquation();
		return true;
	}
	return false;
}

// This returns the (X, Y) points to probe the bed at probe point count.  When probing,
// it returns false.  If called after probing has ended it returns true, and the Z coordinate
// probed is also returned.

bool GCodes::GetProbeCoordinates(int count, float& x, float& y, float& z)
{
	x = reprap.GetMove()->xBedProbePoint(count);
	y = reprap.GetMove()->yBedProbePoint(count);
	z = reprap.GetMove()->zBedProbePoint(count);
	return zProbesSet;
}

bool GCodes::SetPrintZProbe(GCodeBuffer* gb, char* reply)
{
	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
		return false;
	if(gb->Seen(gCodeLetters[Z_AXIS]))
	{
		platform->SetZProbeStopHeight(gb->GetFValue());
		if(gb->Seen('P'))
		{
			platform->SetZProbe(gb->GetIValue());
		}
	} else if (platform->GetZProbeType() == 2)
	{
		snprintf(reply, STRING_LENGTH, "%d (%d)", platform->ZProbe(), platform->ZProbeOnVal());
	}
	else
	{
		snprintf(reply, STRING_LENGTH, "%d", platform->ZProbe());
	}
	return true;
}

// Return the current coordinates as a printable string.  Coordinates
// are updated at the end of each movement, so this won't tell you
// where you are mid-movement.

//Fixed to deal with multiple extruders

char* GCodes::GetCurrentCoordinates()
{
	float liveCoordinates[DRIVES+1];
	reprap.GetMove()->LiveCoordinates(liveCoordinates);

	snprintf(scratchString, STRING_LENGTH, "X:%f Y:%f Z:%f ", liveCoordinates[X_AXIS], liveCoordinates[Y_AXIS], liveCoordinates[Z_AXIS]);
	char eString[STRING_LENGTH];
	for(int i = AXES; i< DRIVES; i++)
	{
		snprintf(eString,STRING_LENGTH,"E%d:%f ",i-AXES,liveCoordinates[i]);
		strncat(scratchString,eString,STRING_LENGTH);
	}
	return scratchString;
}

void GCodes::OpenFileToWrite(const char* directory, const char* fileName, GCodeBuffer *gb)
{
	fileBeingWritten = platform->GetFileStore(directory, fileName, true);
	if(fileBeingWritten == NULL)
	{
		platform->Message(HOST_MESSAGE, "Can't open GCode file for writing.\n");
	}
	else
	{
		gb->SetWritingFileDirectory(directory);
	}
	eofStringCounter = 0;
}

void GCodes::WriteHTMLToFile(char b, GCodeBuffer *gb)
{
	char reply[1];
	reply[0] = 0;

	if(fileBeingWritten == NULL)
	{
		platform->Message(HOST_MESSAGE, "Attempt to write to a null file.\n");
		return;
	}

	fileBeingWritten->Write(b);

	if(b == eofString[eofStringCounter])
	{
		eofStringCounter++;
		if(eofStringCounter >= eofStringLength)
		{
			fileBeingWritten->Close();
			fileBeingWritten = NULL;
			gb->SetWritingFileDirectory(NULL);
			char* r = reply;
			if(platform->Emulating() == marlin)
				r = "Done saving file.";
			HandleReply(false, gb == serialGCode , r, 'M', 560, false);
			return;
		}
	} else
		eofStringCounter = 0;
}

void GCodes::WriteGCodeToFile(GCodeBuffer *gb)
{
	char reply[1];
	reply[0] = 0;

	if(fileBeingWritten == NULL)
	{
		platform->Message(HOST_MESSAGE, "Attempt to write to a null file.\n");
		return;
	}

	// End of file?

	if(gb->Seen('M'))
	{
		if(gb->GetIValue() == 29)
		{
			fileBeingWritten->Close();
			fileBeingWritten = NULL;
			gb->SetWritingFileDirectory(NULL);
			char* r = reply;
			if(platform->Emulating() == marlin)
				r = "Done saving file.";
			HandleReply(false, gb == serialGCode , r, 'M', 29, false);
			return;
		}
	}

	// Resend request?

	if(gb->Seen('G'))
	{
		if(gb->GetIValue() == 998)
		{
			if(gb->Seen('P'))
			{
				snprintf(scratchString, STRING_LENGTH, "%s", gb->GetIValue());
				HandleReply(false, gb == serialGCode , scratchString, 'G', 998, true);
				return;
			}
		}
	}

	fileBeingWritten->Write(gb->Buffer());
	fileBeingWritten->Write('\n');
	HandleReply(false, gb == serialGCode , reply, 'G', 1, false);
}

// Set up a file to print, but don't print it yet.

void GCodes::QueueFileToPrint(const char* fileName)
{
  if(fileToPrint != NULL)
    fileToPrint->Close();
  fileToPrint = platform->GetFileStore(platform->GetGCodeDir(), fileName, false);
  if(fileToPrint == NULL)
	platform->Message(BOTH_ERROR_MESSAGE, "GCode file not found\n");
}

void GCodes::DeleteFile(const char* fileName)
{
  if(!platform->GetMassStorage()->Delete(platform->GetGCodeDir(), fileName))
  {
	snprintf(scratchString, STRING_LENGTH, "Unsuccessful attempt to delete: %s\n", fileName);
	platform->Message(BOTH_ERROR_MESSAGE, scratchString);
  }
}

// Send the config file to USB in response to an M503 command.
// This is not used for processing M503 requests received via the webserver.
bool GCodes::SendConfigToLine()
{
	if(configFile == NULL)
	{
		configFile = platform->GetFileStore(platform->GetSysDir(), platform->GetConfigFile(), false);
		if(configFile == NULL)
		{
			platform->Message(HOST_MESSAGE, "Configuration file not found\n");
			return true;
		}
		platform->GetLine()->Write('\n');
	}

	char b;
	while(configFile->Read(b))
	{
		platform->GetLine()->Write(b);
		if(b == '\n')
			return false;
	}

	platform->GetLine()->Write('\n');
	configFile->Close();
	configFile = NULL;
	return true;
}


// Function to handle dwell delays.  Return true for
// dwell finished, false otherwise.

bool GCodes::DoDwell(GCodeBuffer *gb)
{
  if(!gb->Seen('P'))
    return true;  // No time given - throw it away
  
  float dwell = 0.001*(float)gb->GetLValue(); // P values are in milliseconds; we need seconds
      
  // Wait for all the queued moves to stop
      
  if(!reprap.GetMove()->AllMovesAreFinished())
    return false;
      
  // Are we already in the dwell?
      
  if(dwellWaiting)
  {
    if(platform->Time() - dwellTime >= 0.0)
    {
      dwellWaiting = false;
      reprap.GetMove()->ResumeMoving();
      return true;
    }
    return false;
  }
      
  // New dwell - set it up
      
  dwellWaiting = true;
  dwellTime = platform->Time() + dwell;
  return false;
}

// Set working and standby temperatures for
// a tool.  I.e. handle a G10.

bool GCodes::SetOffsets(GCodeBuffer *gb)
{
  if(gb->Seen('P'))
  {
	  int8_t toolNumber = gb->GetIValue();
	  Tool* tool = reprap.GetTool(toolNumber);
	  if(tool == NULL)
	  {
		  snprintf(scratchString, STRING_LENGTH, "Attempt to set temperatures for non-existent tool: %d\n", toolNumber);
		  platform->Message(HOST_MESSAGE, scratchString);
		  return true;
	  }
	  float standby[HEATERS];
	  float active[HEATERS];
	  int hCount = tool->HeaterCount();
	  if(gb->Seen('R'))
		  gb->GetFloatArray(standby, hCount);
	  if(gb->Seen('S'))
		  gb->GetFloatArray(active, hCount);
	  tool->SetVariables(standby, active);
  }
  return true;  
}

void GCodes::AddNewTool(GCodeBuffer *gb)
{
	if(!gb->Seen('P'))
		return;

	int toolNumber = gb->GetLValue();

	long drives[DRIVES - AXES];  // There can never be more than we have...
	int dCount = DRIVES - AXES;  // Sets the limit and returns the count
	if(gb->Seen('D'))
		gb->GetLongArray(drives, dCount);

	long heaters[HEATERS];
	int hCount = HEATERS;
	if(gb->Seen('H'))
		gb->GetLongArray(heaters, hCount);

	Tool* tool = new Tool(toolNumber, drives, dCount, heaters, hCount);
	reprap.AddTool(tool);
}

// Does what it says.

bool GCodes::DisableDrives()
{
	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
	   return false;
	for(int8_t drive = 0; drive < DRIVES; drive++)
		platform->Disable(drive);
	return true;
}

// Does what it says.

bool GCodes::StandbyHeaters()
{
	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
		return false;
	reprap.GetHeat()->Standby(HOT_BED);
	Tool* tool = reprap.GetCurrentTool();
	if(tool != NULL)
		reprap.StandbyTool(tool->Number());
	return true;
}

void GCodes::SetEthernetAddress(GCodeBuffer *gb, int mCode)
{
	byte eth[4];
	const char* ipString = gb->GetString();
	uint8_t sp = 0;
	uint8_t spp = 0;
	uint8_t ipp = 0;
	while(ipString[sp])
	{
		if(ipString[sp] == '.')
		{
			eth[ipp] = atoi(&ipString[spp]);
			ipp++;
			if(ipp > 3)
			{
				platform->Message(HOST_MESSAGE, "Dud IP address: ");
				platform->Message(HOST_MESSAGE, gb->Buffer());
				platform->Message(HOST_MESSAGE, "\n");
				return;
			}
			sp++;
			spp = sp;
		}else
			sp++;
	}
	eth[ipp] = atoi(&ipString[spp]);
	if(ipp == 3)
	{
		switch(mCode)
		{
		case 552:
			platform->SetIPAddress(eth);
			break;
		case 553:
			platform->SetNetMask(eth);
			break;
		case 554:
			platform->SetGateWay(eth);
			break;

		default:
			platform->Message(HOST_MESSAGE, "Setting ether parameter - dud code.");
		}
	} else
	{
		platform->Message(HOST_MESSAGE, "Dud IP address: ");
		platform->Message(HOST_MESSAGE, gb->Buffer());
		platform->Message(HOST_MESSAGE, "\n");
	}
}


void GCodes::SetMACAddress(GCodeBuffer *gb)
{
	u8_t mac[6];
	const char* ipString = gb->GetString();
	uint8_t sp = 0;
	uint8_t spp = 0;
	uint8_t ipp = 0;
	while(ipString[sp])
	{
		if(ipString[sp] == ':')
		{
			mac[ipp] = strtol(&ipString[spp], NULL, 0);
			ipp++;
			if(ipp > 5)
			{
				platform->Message(HOST_MESSAGE, "Dud MAC address: ");
				platform->Message(HOST_MESSAGE, gb->Buffer());
				platform->Message(HOST_MESSAGE, "\n");
				return;
			}
			sp++;
			spp = sp;
		}else
			sp++;
	}
	mac[ipp] = strtol(&ipString[spp], NULL, 0);
	if(ipp == 5)
	{
		platform->SetMACAddress(mac);
	} else
	{
		platform->Message(HOST_MESSAGE, "Dud MAC address: ");
		platform->Message(HOST_MESSAGE, gb->Buffer());
		platform->Message(HOST_MESSAGE, "\n");
	}
//	snprintf(scratchString, STRING_LENGTH, "MAC: %x:%x:%x:%x:%x:%x\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
//	platform->Message(HOST_MESSAGE, scratchString);
}

void GCodes::HandleReply(bool error, bool fromLine, const char* reply, char gMOrT, int code, bool resend)
{
	if (gMOrT != 'M' || code != 111)	// web server reply for M111 is handled before we get here
	{
		if(error)
			platform->Message(WEB_ERROR_MESSAGE, reply);
		else
			platform->Message(WEB_MESSAGE, reply);
	}

	Compatibility c = platform->Emulating();
	if(!fromLine)
		c = me;

	const char* response = "ok";
	if(resend)
		response = "rs ";

	const char* s = 0;

	switch(c)
	{
	case me:
	case reprapFirmware:
		if(!reply[0])
			return;
		if(error)
			platform->GetLine()->Write("Error: ");
		platform->GetLine()->Write(reply);
		platform->GetLine()->Write("\n");
		return;

	case marlin:

		if(gMOrT == 'M' && code == 20)
		{
			platform->GetLine()->Write("Begin file list\n");
			platform->GetLine()->Write(reply);
			platform->GetLine()->Write("\nEnd file list\n");
			platform->GetLine()->Write(response);
			platform->GetLine()->Write("\n");
			return;
		}

		if(gMOrT == 'M' && code == 28)
		{
			platform->GetLine()->Write(response);
			platform->GetLine()->Write("\n");
			platform->GetLine()->Write(reply);
			platform->GetLine()->Write("\n");
			return;
		}

		if( (gMOrT == 'M' && code == 105) || (gMOrT == 'G' && code == 998))
		{
			platform->GetLine()->Write(response);
			platform->GetLine()->Write(" ");
			platform->GetLine()->Write(reply);
			platform->GetLine()->Write("\n");
			return;
		}

		if(reply[0])
		{
			platform->GetLine()->Write(reply);
			platform->GetLine()->Write("\n");
		}
		platform->GetLine()->Write(response);
		platform->GetLine()->Write("\n");
		return;

	case teacup:
		s = "teacup";
		break;
	case sprinter:
		s = "sprinter";
		break;
	case repetier:
		s = "repetier";
		break;
	default:
		s = "unknown";
	}

	if(s != 0)
	{
		snprintf(scratchString, STRING_LENGTH, "Emulation of %s is not yet supported.\n", s);
		platform->Message(HOST_MESSAGE, scratchString);
	}
}

void GCodes::SetToolHeaters(float temperature)
{
	Tool* tool = reprap.GetCurrentTool();

	if(tool == NULL)
	{
		platform->Message(HOST_MESSAGE, "Setting temperature: no tool selected.\n");
		return;
	}

	float standby[HEATERS];
	float active[HEATERS];
	tool->GetVariables(standby, active);
	for(int8_t h = 0; h < tool->HeaterCount(); h++)
		active[h] = temperature;
	tool->SetVariables(standby, active);
}

// If the GCode to act on is completed, this returns true,
// otherwise false.  It is called repeatedly for a given
// GCode until it returns true for that code.

bool GCodes::ActOnGcode(GCodeBuffer *gb)
{
  int code;
  bool result = true;
  bool error = false;
  bool resend = false;
  bool seen;
  char reply[STRING_LENGTH];

  reply[0] = 0;

  if(gb->Seen('G'))
  {
    code = gb->GetIValue();
    switch(code)
    {
    case 0: // There are no rapid moves...
    case 1: // Ordinary move
      result = SetUpMove(gb);
      break;
      
    case 4: // Dwell
      result = DoDwell(gb);
      break;
      
    case 10: // Set offsets
      result = SetOffsets(gb);
      break;
    
    case 20: // Inches (which century are we living in, here?)
      distanceScale = INCH_TO_MM;
      break;
    
    case 21: // mm
      distanceScale = 1.0;
      break;
    
    case 28: // Home
      if(NoHome())
      {
    	homeAxisMoveCount = 0;
        homeX = gb->Seen(gCodeLetters[X_AXIS]);
        homeY = gb->Seen(gCodeLetters[Y_AXIS]);
        homeZ = gb->Seen(gCodeLetters[Z_AXIS]);
        if(NoHome())
        {
          homeX = true;
          homeY = true;
          homeZ = true;
        }
      }
      result = DoHome(reply, error);
      break;

    case 30: // Z probe/manually set at a position and set that as point P
    	result = SetSingleZProbeAtAPosition(gb);
    	break;

    case 31: // Return the probe value, or set probe variables
    	result = SetPrintZProbe(gb, reply);
    	break;

    case 32: // Probe Z at multiple positions and generate the bed transform
		if (!(axisIsHomed[X_AXIS] && axisIsHomed[Y_AXIS]))
		{
			// We can only do a Z probe if X and Y have already been homed
			strncpy(reply, "Must home X and Y before bed probing", STRING_LENGTH);
			error = true;
			result = true;
		}
		else
		{
			result = DoMultipleZProbe();
		}
    	break;

    case 90: // Absolute coordinates
      drivesRelative = false;
      axesRelative = false;
      break;
      
    case 91: // Relative coordinates
      drivesRelative = true; // Non-axis movements (i.e. extruders)
      axesRelative = true;   // Axis movements (i.e. X, Y and Z)
      break;
      
    case 92: // Set position
      result = SetPositions(gb);
      break;
      
    default:
    	error = true;
    	snprintf(reply, STRING_LENGTH, "invalid G Code: %s", gb->Buffer());
    }
    if(result)
    	HandleReply(error, gb == serialGCode, reply, 'G', code, resend);
    return result;
  }
  
  if(gb->Seen('M'))
  {
    code = gb->GetIValue();
    switch(code)
    {
    case 0: // Stop
    case 1: // Sleep
      if(fileBeingPrinted != NULL)
      {
    	  fileToPrint = fileBeingPrinted;
    	  fileBeingPrinted = NULL;
      }
      if(!DisableDrives())
    	  return false;
      if(!StandbyHeaters())
    	  return false; // Should never happen
      break;
    
    case 18: // Motors off
      result = DisableDrives();
      break;
      
    case 20:  // Deprecated...
      if(platform->Emulating() == me || platform->Emulating() == reprapFirmware)
    	  snprintf(reply, STRING_LENGTH, "GCode files:\n%s", platform->GetMassStorage()->FileList(platform->GetGCodeDir(), gb == serialGCode));
      else
    	  snprintf(reply, STRING_LENGTH, "%s", platform->GetMassStorage()->FileList(platform->GetGCodeDir(), gb == serialGCode));
      break;

    case 21: // Initialise SD - ignore
    	break;

    case 23: // Set file to print
      QueueFileToPrint(gb->GetUnprecedentedString());
      if(platform->Emulating() == marlin)
    	  snprintf(reply, STRING_LENGTH, "%s", "File opened\nFile selected\n");
      break;
      
    case 24: // Print/resume-printing the selected file
      if(fileBeingPrinted != NULL)
    	  break;
      fileBeingPrinted = fileToPrint;
      fileToPrint = NULL;
      break;
      
    case 25: // Pause the print
    	fileToPrint = fileBeingPrinted;
    	fileBeingPrinted = NULL;
    	break;

    case 27: // Report print status - Deprecated
    	if(this->PrintingAFile())
    		strncpy(reply, "SD printing.", STRING_LENGTH);
    	else
    		strncpy(reply, "Not SD printing.", STRING_LENGTH);
    	break;

    case 28: // Write to file
    	{
			const char* str = gb->GetUnprecedentedString();
			OpenFileToWrite(platform->GetGCodeDir(), str, gb);
			snprintf(reply, STRING_LENGTH, "Writing to file: %s", str);
    	}
    	break;

    case 29: // End of file being written; should be intercepted before getting here
    	platform->Message(HOST_MESSAGE, "GCode end-of-file being interpreted.\n");
    	break;

    case 30:	// Delete file
    	DeleteFile(gb->GetUnprecedentedString());
    	break;

    case 82:
    	for(int8_t extruder = AXES; extruder < DRIVES; extruder++)
    		lastPos[extruder - AXES] = 0.0;
    	drivesRelative = false;
    	break;

    case 83:
    	for(int8_t extruder = AXES; extruder < DRIVES; extruder++)
    		lastPos[extruder - AXES] = 0.0;
    	drivesRelative = true;

    	break;

    case 84: // Motors off - deprecated, use M18
        result = DisableDrives();
        break;

    case 85: // Set inactive time
    	break;

    case 92: // Set/report steps/mm for some axes
    	seen = false;
    	for(int8_t axis = 0; axis < AXES; axis++)
    	{
    		if(gb->Seen(gCodeLetters[axis]))
    		{
    			platform->SetDriveStepsPerUnit(axis, gb->GetFValue());
    			seen = true;
    		}
    	}

    	if(gb->Seen(EXTRUDE_LETTER))
    	{
    		seen = true;
    		float eVals[DRIVES-AXES];
    		int eCount = DRIVES-AXES;
    		gb->GetFloatArray(eVals, eCount);
    		if(eCount != DRIVES-AXES)
    		{
    			snprintf(scratchString, STRING_LENGTH, "Setting steps/mm - wrong number of E drives: %s\n", gb->Buffer());
    			platform->Message(HOST_MESSAGE, scratchString);
    		} else
    		{
    			for(int8_t e = 0; e < eCount; e++)
    				platform->SetDriveStepsPerUnit(AXES + e, eVals[e]);
    		}
    	}

    	if(!seen)
    	{
    		snprintf(reply, STRING_LENGTH, "Steps/mm: X: %d, Y: %d, Z: %d, E: ",
    				(int)platform->DriveStepsPerUnit(X_AXIS), (int)platform->DriveStepsPerUnit(Y_AXIS),
    				(int)platform->DriveStepsPerUnit(Z_AXIS));
        	for(int8_t drive = AXES; drive < DRIVES; drive++)
        	{
        		snprintf(scratchString, STRING_LENGTH, "%f", platform->DriveStepsPerUnit(drive));
        		strncat(reply, scratchString, STRING_LENGTH);
        		if(drive < DRIVES-1)
        			strncat(reply, ":", STRING_LENGTH);
        	}
    	} else
    		reprap.GetMove()->SetStepHypotenuse();
        break;


    case 98:
    	if(gb->Seen('P'))
    		result = DoFileCannedCycles(gb->GetString());
    	break;

    case 99:
    	result = FileCannedCyclesReturn();
    	break;

    case 104: // Deprecated.  This sets the active temperature of every heater of the active tool
    	if(gb->Seen('S'))
    	{
    		float temperature = gb->GetFValue();
    		SetToolHeaters(temperature);
    	}
    	break;

    case 105: // Deprecated...
    	strncpy(reply, "T:", STRING_LENGTH);
    	for(int8_t heater = 1; heater < HEATERS; heater++)
    	{
    		if(!reprap.GetHeat()->SwitchedOff(heater))
    		{
    			snprintf(scratchString, STRING_LENGTH, "%.1f ", reprap.GetHeat()->GetTemperature(heater));
    			strncat(reply, scratchString, STRING_LENGTH);
    		}
    	}
    	snprintf(scratchString, STRING_LENGTH, "B: %.1f ", reprap.GetHeat()->GetTemperature(0));
    	strncat(reply, scratchString, STRING_LENGTH);
    	break;
   
    case 106: // Fan on or off
    	if(gb->Seen('S'))
    		platform->CoolingFan(gb->GetFValue());
      break;
    
    case 107: // Fan off - deprecated
    	platform->CoolingFan(0.0);
      break;
      
    case 110: // Set line numbers - line numbers are dealt with in the GCodeBuffer class
    	break;

    case 111: // Debug level
    	if(gb->Seen('S'))
    	{
    		int dbv = gb->GetIValue();
    		if(dbv == WEB_DEBUG_TRUE)
    			reprap.GetWebserver()->WebDebug(true);
    		else if (dbv == WEB_DEBUG_FALSE)
    			reprap.GetWebserver()->WebDebug(false);
    		else
    			reprap.SetDebug(dbv);
    	}
    	break;

    case 112: // Emergency stop - acted upon in Webserver, but also here in case it comes from USB etc.
    	reprap.EmergencyStop();
    	break;

    case 114: // Deprecated
    	{
    		const char* str = GetCurrentCoordinates();
			if(str != 0)
			{
				strncpy(reply, str, STRING_LENGTH);
			} else
    		result = false;
    	}
    	break;

    case 115: // Print firmware version
    	snprintf(reply, STRING_LENGTH, "FIRMWARE_NAME:%s FIRMWARE_VERSION:%s ELECTRONICS:%s DATE:%s", NAME, VERSION, ELECTRONICS, DATE);
    	break;

    case 109: // Deprecated
    	if(gb->Seen('S'))
    	{
    		float temperature = gb->GetFValue();
    		SetToolHeaters(temperature);
    	}
    	// Fall through to the general check...
    case 116: // Wait for everything, especially set temperatures
    	if(!AllMovesAreFinishedAndMoveBufferIsLoaded())
    		return false;
    	result = reprap.GetHeat()->AllHeatersAtSetTemperatures();
    	break;

    	//TODO M119
    case 119:
        platform->Message(HOST_MESSAGE, "M119 - endstop status not yet implemented\n");
    	break;

    case 120:
    	result = Push();
    	break;

    case 121:
      result = Pop();
      break;
    
    case 122:
      reprap.Diagnostics();
      break;
      
    case 126: // Valve open
      platform->Message(HOST_MESSAGE, "M126 - valves not yet implemented\n");
      break;
      
    case 127: // Valve closed
      platform->Message(HOST_MESSAGE, "M127 - valves not yet implemented\n");
      break;
      
    case 135: // Set PID sample interval
    	break;

    case 140: // Set bed temperature
    	if(gb->Seen('S'))
    	{
    		if(HOT_BED >= 0)
    		{
    			reprap.GetHeat()->SetActiveTemperature(HOT_BED, gb->GetFValue());
    			reprap.GetHeat()->Activate(HOT_BED);
    		}
    	}
    	if(gb->Seen('R'))
    	{
    		if(HOT_BED >= 0)
    			reprap.GetHeat()->SetStandbyTemperature(HOT_BED, gb->GetFValue());
    	}
      break;
    
    case 141: // Chamber temperature
      platform->Message(HOST_MESSAGE, "M141 - heated chamber not yet implemented\n");
      break;

    case 160: //number of mixing filament drives  TODO: With tools defined, is this needed?
    	if(gb->Seen('S'))
		{
			int iValue=gb->GetIValue();
			platform->SetMixingDrives(iValue);
		}
		break;

    case 190: // Deprecated...
    	if(gb->Seen('S'))
    	{
    		if(HOT_BED >= 0)
    		{
    			reprap.GetHeat()->SetActiveTemperature(HOT_BED, gb->GetFValue());
    			reprap.GetHeat()->Activate(HOT_BED);
    			result = reprap.GetHeat()->HeaterAtSetTemperature(HOT_BED);
    		}
    	}
      break;

    case 201: // Set/print axis accelerations  FIXME - should these be in /min not /sec ?
    	seen = false;
    	for(int8_t axis = 0; axis < AXES; axis++)
    	{
    		if(gb->Seen(gCodeLetters[axis]))
    		{
    			platform->SetAcceleration(axis, gb->GetFValue()*distanceScale);
    			seen = true;
    		}
    	}

    	if(gb->Seen(EXTRUDE_LETTER))
    	{
    		seen = true;
    		float eVals[DRIVES-AXES];
    		int eCount = DRIVES-AXES;
    		gb->GetFloatArray(eVals, eCount);
    		if(eCount != DRIVES-AXES)
    		{
    			snprintf(scratchString, STRING_LENGTH, "Setting accelerations - wrong number of E drives: %s\n", gb->Buffer());
    			platform->Message(HOST_MESSAGE, scratchString);
    		} else
    		{
    			for(int8_t e = 0; e < eCount; e++)
    				platform->SetAcceleration(AXES + e, eVals[e]*distanceScale);
    		}
    	}

    	if(!seen)
    	{
    		snprintf(reply, STRING_LENGTH, "Accelerations: X: %f, Y: %f, Z: %f, E: ",
    				platform->Acceleration(X_AXIS)/distanceScale, platform->Acceleration(Y_AXIS)/distanceScale,
    				platform->Acceleration(Z_AXIS)/distanceScale);
        	for(int8_t drive = AXES; drive < DRIVES; drive++)
        	{
        		snprintf(scratchString, STRING_LENGTH, "%f", platform->Acceleration(drive)/distanceScale);
        		strncat(reply, scratchString, STRING_LENGTH);
        		if(drive < DRIVES-1)
        			strncat(reply, ":", STRING_LENGTH);
        	}
    	}

    	break;

    case 203: // Set/print maximum feedrates
       	seen = false;
        	for(int8_t axis = 0; axis < AXES; axis++)
        	{
        		if(gb->Seen(gCodeLetters[axis]))
        		{
        			platform->SetMaxFeedrate(axis, gb->GetFValue()*distanceScale*0.016666667); // G Code feedrates are in mm/minute; we need mm/sec
        			seen = true;
        		}
        	}

        	if(gb->Seen(EXTRUDE_LETTER))
        	{
        		seen = true;
        		float eVals[DRIVES-AXES];
        		int eCount = DRIVES-AXES;
        		gb->GetFloatArray(eVals, eCount);
        		if(eCount != DRIVES-AXES)
        		{
        			snprintf(scratchString, STRING_LENGTH, "Setting feedrates - wrong number of E drives: %s\n", gb->Buffer());
        			platform->Message(HOST_MESSAGE, scratchString);
        		} else
        		{
        			for(int8_t e = 0; e < eCount; e++)
        				platform->SetMaxFeedrate(AXES + e, eVals[e]*distanceScale*0.016666667);
        		}
        	}

        	if(!seen)
        	{
        		snprintf(reply, STRING_LENGTH, "Maximum feedrates: X: %f, Y: %f, Z: %f, E: ",
        				platform->MaxFeedrate(X_AXIS)/(distanceScale*0.016666667), platform->MaxFeedrate(Y_AXIS)/(distanceScale*0.016666667),
        				platform->MaxFeedrate(Z_AXIS)/(distanceScale*0.016666667));
            	for(int8_t drive = AXES; drive < DRIVES; drive++)
            	{
            		snprintf(scratchString, STRING_LENGTH, "%f", platform->MaxFeedrate(drive)/(distanceScale*0.016666667));
            		strncat(reply, scratchString, STRING_LENGTH);
            		if(drive < DRIVES-1)
            			strncat(reply, ":", STRING_LENGTH);
            	}
        	}
    	break;

    case 205:  //M205 advanced settings:  minimum travel speed S=while printing T=travel only,  B=minimum segment time X= maximum xy jerk, Z=maximum Z jerk
    	break;

    case 206:  // Offset axes - Depricated
    	result = OffsetAxes(gb);
    	break;

    case 208: // Set maximum axis lengths
    	for(int8_t axis = 0; axis < AXES; axis++)
    	{
    		if(gb->Seen(gCodeLetters[axis]))
    		{
    			float value = gb->GetFValue()*distanceScale;
    			platform->SetAxisLength(axis, value);
    		}
    	}
    	break;

    case 210: // Set homing feedrates
    	for(int8_t axis = 0; axis < AXES; axis++)
    	{
    		if(gb->Seen(gCodeLetters[axis]))
    		{
    			float value = gb->GetFValue()*distanceScale*0.016666667;
    			platform->SetHomeFeedRate(axis, value);
    		}
    	}
    	break;

    case 301: // Set hot end PID values
    	{
    		if(!gb->Seen('H')) // Must specify the heater
    			break;

    		int8_t heater = gb->GetIValue();

    		float pValue, iValue, dValue;
    		bool seen = false;
    		if (gb->Seen('P'))
    		{
    			pValue = gb->GetFValue();
    			seen = true;
    		}
    		else
    		{
    			pValue = platform->PidKp(1);
    		}
    		if (gb->Seen('I'))
    		{
    			iValue = gb->GetFValue();
    			seen = true;
    		}
    		else
    		{
    			iValue = platform->PidKi(1);
    		}
    		if (gb->Seen('D'))
    		{
    			dValue = gb->GetFValue();
    			seen = true;
    		}
    		else
    		{
    			dValue = platform->PidKd(1);
    		}

    		if (seen)
    		{
    			platform->SetPidValues(heater, pValue, iValue, dValue);
    		}
    		else
    		{
        		snprintf(reply, STRING_LENGTH, "Heater %d - P:%f I:%f D: %f\n", heater, pValue, iValue, dValue);
    		}
    	}
    	break;

    case 302: // Allow cold extrudes
    	break;

    case 304: // Set thermistor parameters
    	break;

    case 503: // list variable settings
    	result = SendConfigToLine();
    	break;

    case 540:
    	if(gb->Seen('P'))
    	    SetMACAddress(gb);
    	break;

    case 550: // Set machine name
        	if(gb->Seen('P'))
        		reprap.GetWebserver()->SetName(gb->GetString());
        	break;

    case 551: // Set password
    	if(gb->Seen('P'))
    		reprap.GetWebserver()->SetPassword(gb->GetString());
    	break;

    case 552: // Set/Get IP address
    	if(gb->Seen('P'))
    		SetEthernetAddress(gb, code);
    	else
    	{
    		const byte *ip = platform->IPAddress();
    		snprintf(reply, STRING_LENGTH, "IP address: %d.%d.%d.%d\n ", ip[0], ip[1], ip[2], ip[3]);
    	}
    	break;

    case 553: // Set/Get netmask
    	if(gb->Seen('P'))
    		SetEthernetAddress(gb, code);
    	else
    	{
    		const byte *nm = platform->NetMask();
    		snprintf(reply, STRING_LENGTH, "Net mask: %d.%d.%d.%d\n ", nm[0], nm[1], nm[2], nm[3]);
    	}
    	break;

    case 554: // Set/Get gateway
    	if(gb->Seen('P'))
    		SetEthernetAddress(gb, code);
    	else
    	{
    		const byte *gw = platform->GateWay();
    		snprintf(reply, STRING_LENGTH, "Gateway: %d.%d.%d.%d\n ", gw[0], gw[1], gw[2], gw[3]);
    	}
    	break;

    case 555: // Set firmware type to emulate
    	if(gb->Seen('P'))
    		platform->SetEmulating((Compatibility)gb->GetIValue());
    	break;

    case 556: // Axis compensation
    	if(gb->Seen('S'))
    	{
    		float value = gb->GetFValue();
    		for(int8_t axis = 0; axis < AXES; axis++)
    			if(gb->Seen(gCodeLetters[axis]))
    				reprap.GetMove()->SetAxisCompensation(axis, gb->GetFValue()/value);
    	}
    	break;

    case 557: // Set Z probe point coordinates
    	if(gb->Seen('P'))
    	{
    		int iValue = gb->GetIValue();
    		if(gb->Seen(gCodeLetters[X_AXIS]))
    			reprap.GetMove()->SetXBedProbePoint(iValue, gb->GetFValue());
    		if(gb->Seen(gCodeLetters[Y_AXIS]))
    		    reprap.GetMove()->SetYBedProbePoint(iValue, gb->GetFValue());
    	}
    	break;

    case 558: // Set Z probe type
    	if(gb->Seen('P'))
    	{
    		platform->SetZProbeType(gb->GetIValue());
    	}
    	else
    	{
    		snprintf(reply, STRING_LENGTH, "Z Probe: %d", platform->GetZProbeType());
    	}
    	break;

    case 559: // Upload config.g
    	{
    		const char* str;
			if(gb->Seen('P'))
				str = gb->GetString();
			else
				str = platform->GetConfigFile();
			OpenFileToWrite(platform->GetSysDir(), str, gb);
			snprintf(reply, STRING_LENGTH, "Writing to file: %s", str);
    	}
    	break;

    case 560: // Upload reprap.htm
    	{
    		const char* str = INDEX_PAGE;
    		OpenFileToWrite(platform->GetWebDir(), str, gb);
    		snprintf(reply, STRING_LENGTH, "Writing to file: %s", str);
    	}
     	break;

    case 561:
    	reprap.GetMove()->SetIdentityTransform();
    	break;

    case 562: // Reset temperature fault - use with great caution
    	if(gb->Seen('P'))
    	{
    	    int iValue = gb->GetIValue();
    	    reprap.GetHeat()->ResetFault(iValue);
    	}
    	break;

    case 563: // Define tool
    	AddNewTool(gb);
    	break;

    case 564: // Think outside the box?
    	if(gb->Seen('S'))
    	    limitAxes = (gb->GetIValue() != 0);
    	break;

    case 566: // Set/print minimum feedrates
       	seen = false;
        	for(int8_t axis = 0; axis < AXES; axis++)
        	{
        		if(gb->Seen(gCodeLetters[axis]))
        		{
        			platform->SetInstantDv(axis, gb->GetFValue()*distanceScale*0.016666667); // G Code feedrates are in mm/minute; we need mm/sec
        			seen = true;
        		}
        	}

        	if(gb->Seen(EXTRUDE_LETTER))
        	{
        		seen = true;
        		float eVals[DRIVES-AXES];
        		int eCount = DRIVES-AXES;
        		gb->GetFloatArray(eVals, eCount);
        		if(eCount != DRIVES-AXES)
        		{
        			snprintf(scratchString, STRING_LENGTH, "Setting feedrates - wrong number of E drives: %s\n", gb->Buffer());
        			platform->Message(HOST_MESSAGE, scratchString);
        		} else
        		{
        			for(int8_t e = 0; e < eCount; e++)
        				platform->SetInstantDv(AXES + e, eVals[e]*distanceScale*0.016666667);
        		}
        	}

        	if(!seen)
        	{
        		snprintf(reply, STRING_LENGTH, "Minimum feedrates: X: %f, Y: %f, Z: %f, E: ",
        				platform->InstantDv(X_AXIS)/(distanceScale*0.016666667), platform->InstantDv(Y_AXIS)/(distanceScale*0.016666667),
        				platform->InstantDv(Z_AXIS)/(distanceScale*0.016666667));
            	for(int8_t drive = AXES; drive < DRIVES; drive++)
            	{
            		snprintf(scratchString, STRING_LENGTH, "%f", platform->InstantDv(drive)/(distanceScale*0.016666667));
            		strncat(reply, scratchString, STRING_LENGTH);
            		if(drive < DRIVES-1)
            			strncat(reply, ":", STRING_LENGTH);
            	}
        	}
    	break;

    case 906: // Set Motor currents

    	for(int8_t axis = 0; axis < AXES; axis++)
    	{
    		if(gb->Seen(gCodeLetters[axis]))
    			platform->SetMotorCurrent(axis, gb->GetFValue());
    	}

    	if(gb->Seen(EXTRUDE_LETTER))
    	{
    		float eVals[DRIVES-AXES];
    		int eCount = DRIVES-AXES;
    		gb->GetFloatArray(eVals, eCount);
    		if(eCount != DRIVES-AXES)
    		{
    			snprintf(scratchString, STRING_LENGTH, "Setting motor currents - wrong number of E drives: %s\n", gb->Buffer());
    			platform->Message(HOST_MESSAGE, scratchString);
    		} else
    		{
    			for(int8_t e = 0; e < eCount; e++)
    				platform->SetMotorCurrent(AXES + e, eVals[e]);
    		}
    	}
    	break;

    case 998:
    	if(gb->Seen('P'))
    	{
    	    snprintf(reply, STRING_LENGTH, "%s", gb->GetIValue());
    	    resend = true;
    	}
    	break;

    case 999: // Reset. FIXME: Implement this?
    	break;
     
    default:
      error = true;
      snprintf(reply, STRING_LENGTH, "invalid M Code: %s", gb->Buffer());
    }
    if(result)
    	HandleReply(error, gb == serialGCode, reply, 'M', code, resend);
    return result;
  }
  
  // Selecting a tool

  if(gb->Seen('T'))
  {
    result = ChangeTool(gb->GetIValue());
    if(result)
    	HandleReply(error, gb == serialGCode, reply, 'T', code, resend);
    return result;
  }
  
  // An empty buffer jumps to here and gets discarded

  if(result)
  	HandleReply(error, gb == serialGCode, reply, 'X', code, resend);

  return result;
}

bool GCodes::ChangeTool(int newToolNumber)
{
    Tool* oldTool = reprap.GetCurrentTool();
    Tool* newTool = reprap.GetTool(newToolNumber);

    // If old and new are the same still follow the sequence -
    // The user may want the macros run.

    switch(toolChangeSequence)
    {
    case 0: // Pre-release sequence for the old tool (if any)
    	if(oldTool != NULL)
    	{
    		snprintf(scratchString, STRING_LENGTH, "tfree%d.g", oldTool->Number());
    		if(DoFileCannedCycles(scratchString))
    			toolChangeSequence++;
    	} else
    		toolChangeSequence++;
    	return false;

    case 1: // Release the old tool (if any)
    	if(oldTool != NULL)
    		reprap.StandbyTool(oldTool->Number());
    	toolChangeSequence++;
    	return false;

    case 2: // Run the pre-tool-change canned cycle for the new tool (if any)
    	if(newTool != NULL)
    	{
    		snprintf(scratchString, STRING_LENGTH, "tpre%d.g", newToolNumber);
    		if(DoFileCannedCycles(scratchString))
    			toolChangeSequence++;
    	} else
    		toolChangeSequence++;
    	return false;

    case 3: // Select the new tool (even if it doesn't exist - that just deselects all tools)
    	reprap.SelectTool(newToolNumber);
   		toolChangeSequence++;
    	return false;

    case 4: // Run the post-tool-change canned cycle for the new tool (if any)
    	if(newTool != NULL)
    	{
    		snprintf(scratchString, STRING_LENGTH, "tpost%d.g", newToolNumber);
    		if(DoFileCannedCycles(scratchString))
    			toolChangeSequence++;
    	} else
    		toolChangeSequence++;
    	return false;

    case 5: // All done
    	toolChangeSequence = 0;
    	return true;

    default:
    	platform->Message(HOST_MESSAGE, "Tool change - dud sequence number.\n");
    }

    toolChangeSequence = 0;
    return true;
}



//*************************************************************************************

// This class stores a single G Code and provides functions to allow it to be parsed

GCodeBuffer::GCodeBuffer(Platform* p, const char* id)
{ 
  platform = p;
  identity = id;
  writingFileDirectory = NULL;  // Has to be done here as Init() is called every line.
}

void GCodeBuffer::Init()
{
  gcodePointer = 0;
  readPointer = -1;
  inComment = false;   
}

int GCodeBuffer::CheckSum()
{
	int cs = 0;
	for(int i = 0; gcodeBuffer[i] != '*' && gcodeBuffer[i] != 0; i++)
	   cs = cs ^ gcodeBuffer[i];
	cs &= 0xff;  // Defensive programming...
	return cs;
}

// Add a byte to the code being assembled.  If false is returned, the code is
// not yet complete.  If true, it is complete and ready to be acted upon.

bool GCodeBuffer::Put(char c)
{
  bool result = false;
  gcodeBuffer[gcodePointer] = c;
  
  if(c == ';')
    inComment = true;
    
  if(c == '\n' || !c)
  {
    gcodeBuffer[gcodePointer] = 0;
    Init();
    if(reprap.Debug() && gcodeBuffer[0] && !writingFileDirectory) // Don't bother with blank/comment lines
    {
      platform->Message(HOST_MESSAGE, identity);
      platform->Message(HOST_MESSAGE, gcodeBuffer);
      platform->Message(HOST_MESSAGE, "\n"); 
    }

    // Deal with line numbers and checksums

    if(Seen('*'))
    {
    	int csSent = GetIValue();
    	int csHere = CheckSum();
    	Seen('N');
    	if(csSent != csHere)
    	{
    		snprintf(gcodeBuffer, GCODE_LENGTH, "M998 P%d", GetIValue());
    		Init();
    		result = true;
    		return result;
    	}

    	// Strip out the line number and checksum

    	while(gcodeBuffer[gcodePointer] != ' ' && gcodeBuffer[gcodePointer])
    		gcodePointer++;

    	// Anything there?

    	if(!gcodeBuffer[gcodePointer])
    	{
    		// No...
    		gcodeBuffer[0] = 0;
    		Init();
    		result = true;
    		return result;
    	}

    	// Yes...

    	gcodePointer++;
    	int gp2 = 0;
    	while(gcodeBuffer[gcodePointer] != '*' && gcodeBuffer[gcodePointer])
    	{
    		gcodeBuffer[gp2] = gcodeBuffer[gcodePointer++];
    		gp2++;
    	}
    	gcodeBuffer[gp2] = 0;
    	Init();
    }

    result = true;
  } else
  {
    if(!inComment || writingFileDirectory)
      gcodePointer++;
  }
  
  if(gcodePointer >= GCODE_LENGTH)
  {
    platform->Message(HOST_MESSAGE, "G Code buffer length overflow.\n");
    gcodePointer = 0;
    gcodeBuffer[0] = 0;
  }
  
  return result;
}   

// Is 'c' in the G Code string?
// Leave the pointer there for a subsequent read.

bool GCodeBuffer::Seen(char c)
{
  readPointer = 0;
  while(gcodeBuffer[readPointer])
  {
    if(gcodeBuffer[readPointer] == c)
      return true;
    readPointer++;
  }
  readPointer = -1;
  return false;
}

// Get a float after a G Code letter found by a call to Seen()

float GCodeBuffer::GetFValue()
{
  if(readPointer < 0)
  {
     platform->Message(HOST_MESSAGE, "GCodes: Attempt to read a GCode float before a search.\n");
     readPointer = -1;
     return 0.0;
  }
  float result = (float)strtod(&gcodeBuffer[readPointer + 1], 0);
  readPointer = -1;
  return result; 
}

// Get a :-separated list of floats after a key letter

const void GCodeBuffer::GetFloatArray(float a[], int& returnedLength)
{
	int length = 0;
	if(readPointer < 0)
	{
		platform->Message(HOST_MESSAGE, "GCodes: Attempt to read a GCode float array before a search.\n");
		readPointer = -1;
		returnedLength = 0;
		return;
	}

	bool inList = true;
	while(inList)
	{
		if(length >= returnedLength) // Array limit has been set in here
		{
			snprintf(scratchString, STRING_LENGTH, "GCodes: Attempt to read a GCode float array that is too long: %s\n", gcodeBuffer);
			platform->Message(HOST_MESSAGE, scratchString);
			readPointer = -1;
			returnedLength = 0;
			return;
		}
		a[length] = (float)strtod(&gcodeBuffer[readPointer + 1], 0);
		length++;
		readPointer++;
		while(gcodeBuffer[readPointer] && (gcodeBuffer[readPointer] != ' ') && (gcodeBuffer[readPointer] != LIST_SEPARATOR))
			readPointer++;
		if(gcodeBuffer[readPointer] != LIST_SEPARATOR)
			inList = false;
	}

	// Special case if there is one entry and returnedLength requests several.
	// Fill the array with the first entry.

	if(length == 1 && returnedLength > 1)
	{
		for(int8_t i = 1; i < returnedLength; i++)
			a[i] = a[0];
	} else
		returnedLength = length;

	readPointer = -1;
}

// Get a :-separated list of longs after a key letter

const void GCodeBuffer::GetLongArray(long l[], int& returnedLength)
{
	int length = 0;
	if(readPointer < 0)
	{
		platform->Message(HOST_MESSAGE, "GCodes: Attempt to read a GCode long array before a search.\n");
		readPointer = -1;
		return;
	}

	bool inList = true;
	while(inList)
	{
		if(length >= returnedLength) // Array limit has been set in here
		{
			snprintf(scratchString, STRING_LENGTH, "GCodes: Attempt to read a GCode long array that is too long: %s\n", gcodeBuffer);
			platform->Message(HOST_MESSAGE, scratchString);
			readPointer = -1;
			returnedLength = 0;
			return;
		}
		l[length] = strtol(&gcodeBuffer[readPointer + 1], 0, 0);
		length++;
		readPointer++;
		while(gcodeBuffer[readPointer] && (gcodeBuffer[readPointer] != ' ') && (gcodeBuffer[readPointer] != LIST_SEPARATOR))
			readPointer++;
		if(gcodeBuffer[readPointer] != LIST_SEPARATOR)
			inList = false;
	}
	returnedLength = length;
	readPointer = -1;
}

// Get a string after a G Code letter found by a call to Seen().
// It will be the whole of the rest of the GCode string, so strings
// should always be the last parameter.

const char* GCodeBuffer::GetString()
{
	if(readPointer < 0)
	{
		platform->Message(HOST_MESSAGE, "GCodes: Attempt to read a GCode string before a search.\n");
		readPointer = -1;
		return "";
	}
	const char* result = &gcodeBuffer[readPointer+1];
	readPointer = -1;
	return result;
}

// This returns a pointer to the end of the buffer where a
// string starts.  It assumes that an M or G search has
// been done followed by a GetIValue(), so readPointer will
// be -1.  It absorbs "M/Gnnn " (including the space) from the
// start and returns a pointer to the next location.

// This is provided for legacy use, in particular in the M23
// command that sets the name of a file to be printed.  In
// preference use GetString() which requires the string to have
// been preceded by a tag letter.

const char* GCodeBuffer::GetUnprecedentedString()
{
  readPointer = 0;
  while(gcodeBuffer[readPointer] && gcodeBuffer[readPointer] != ' ')
	  readPointer++;

  if(!gcodeBuffer[readPointer])
  {
     platform->Message(HOST_MESSAGE, "GCodes: String expected but not seen.\n");
     readPointer = -1;
     return gcodeBuffer; // Good idea?
  }

  char* result = &gcodeBuffer[readPointer+1];
  readPointer = -1;
  return result;
}


// Get an long after a G Code letter

long GCodeBuffer::GetLValue()
{
  if(readPointer < 0)
  {
    platform->Message(HOST_MESSAGE, "GCodes: Attempt to read a GCode int before a search.\n");
    readPointer = -1;
    return 0;
  }
  long result = strtol(&gcodeBuffer[readPointer + 1], 0, 0);
  readPointer = -1;
  return result;  
}