Preliminary version for serving all files for Duet

Changed webserver and network code to support multiple concurrent
connections
Removed support for differential-mode ultrasonic z-sensor
Reduced X and Y instantDv from 15 to 10 mm/sec to allow outlines of
holes to e drawn at lower speed
Changed temperature reading code to give thermistor disconnected reading
of -273C when there is a negative high ADC offset correction

Configuration.h

@@ -24,8 +24,8 @@ Licence: GPL
 #define CONFIGURATION_H
 
 #define NAME "RepRapFirmware"
-#define VERSION "0.57y-dc42"
-#define DATE "2014-03-28"
+#define VERSION "0.57z-alpha-dc42"
+#define DATE "2014-04-06"
 #define LAST_AUTHOR "dc42"
 
 // Other firmware that we might switch to be compatible with.

Network.cpp

@@ -0,0 +1,439 @@
+/****************************************************************************************************
+
+ RepRapFirmware - Network: RepRapPro Ormerod with Arduino Due controller
+
+  Separated out from Platform.cpp by dc42, 2014-04-05
+
+ ****************************************************************************************************/
+
+#include "RepRapFirmware.h"
+#include "DueFlashStorage.h"
+
+const uint8_t windowedSendPackets = 2;
+
+
+//***************************************************************************************************
+
+// Network/Ethernet class
+
+// C calls to interface with LWIP (http://savannah.nongnu.org/projects/lwip/)
+// These are implemented in, and called from, a modified version of httpd.c
+// in the network directory.
+
+extern "C"
+{
+
+// Transmit data to the Network
+
+void RepRapNetworkSendOutput(char* data, int length, void* pcb, void* hs);
+
+// Ask whether it is OK to send
+int RepRapNetworkCanSend(void* hs);
+
+void RepRapNetworkConnectionError(void* h)
+{
+	reprap.GetPlatform()->GetNetwork()->ConnectionError(h);
+}
+
+// Called to put out a message via the RepRap firmware.
+
+void RepRapNetworkMessage(const char* s)
+{
+	reprap.GetPlatform()->Message(HOST_MESSAGE, s);
+}
+
+// Called to push data into the RepRap firmware.
+
+void RepRapNetworkReceiveInput(const char* data, int length, void* pcb, void* hs)
+{
+	reprap.GetPlatform()->GetNetwork()->ReceiveInput(data, length, pcb, hs);
+}
+
+// Called when transmission of outgoing data is complete to allow
+// the RepRap firmware to write more.
+
+void RepRapNetworkSentPacketAcknowledged(void *hs)
+{
+	reprap.GetPlatform()->GetNetwork()->SentPacketAcknowledged(hs);
+}
+
+}	// extern "C"
+
+Network::Network()
+{
+	active = false;
+	ethPinsInit();
+
+	//ResetEther();
+
+	// Construct the free list buffer
+
+	freeTransactions = NULL;
+	readyTransactions = NULL;
+	writingTransactions = NULL;
+	closingTransactions = NULL;
+	for (int8_t i = 0; i < HTTP_STATE_SIZE; i++)
+	{
+		freeTransactions = new NetRing(freeTransactions);
+	}
+}
+
+void Network::AppendTransaction(NetRing** list, NetRing *r)
+{
+	r->next = NULL;
+	while (*list != NULL)
+	{
+		list = &((*list)->next);
+	}
+	*list = r;
+}
+
+void Network::Init()
+{
+	init_ethernet(reprap.GetPlatform()->IPAddress(), reprap.GetPlatform()->NetMask(), reprap.GetPlatform()->GateWay());
+	active = true;
+}
+
+void Network::Spin()
+{
+//	debugPrintf("NetSpinEnter\n");
+	if (active)
+	{
+		ethernet_task();			// keep the Ethernet running
+
+		// See if we can send anything
+		NetRing* r = writingTransactions;
+		if (r != NULL)
+		{
+			bool doClose = r->TrySendData();	// we must leave r on the list for now because of possible callback to release the input buffer
+			writingTransactions = r->next;
+			if (doClose)
+			{
+				r->closeRequestedTime = reprap.GetPlatform()->Time();
+				AppendTransaction(&closingTransactions, r);
+			}
+			else
+			{
+				AppendTransaction(&writingTransactions, r);
+			}
+		}
+
+		// See if we can close any connections
+		r = closingTransactions;
+		if (r != NULL)
+		{
+			if (reprap.GetPlatform()->Time() - r->closeRequestedTime >= CLIENT_CLOSE_DELAY)
+			{
+				r->Close();
+				closingTransactions = r->next;
+				AppendTransaction(&freeTransactions, r);
+			}
+		}
+	}
+//	debugPrintf("NetSpinExit\n");
+}
+
+bool Network::HaveData() const
+{
+	return active && readyTransactions != NULL;
+}
+
+bool Network::Read(char& b)
+{
+	if (readyTransactions != NULL)
+	{
+		return readyTransactions->Read(b);
+	}
+	return false;
+}
+
+void Network::Write(char b)
+{
+	if (readyTransactions != NULL)
+	{
+		readyTransactions->Write(b);
+	}
+}
+
+void Network::Write(const char* s)
+{
+	if (readyTransactions != NULL)
+	{
+		readyTransactions->Write(s);
+	}
+}
+
+void Network::SentPacketAcknowledged(void *hs)
+{
+	NetRing *r = writingTransactions;
+	while (r != NULL && r->hs != hs)
+	{
+		r = r->next;
+	}
+	if (r != NULL)
+	{
+		r->SentPacketAcknowledged();
+		return;
+	}
+
+	r = closingTransactions;
+	while (r != NULL && r->hs != hs)
+	{
+		r = r->next;
+	}
+	if (r != NULL)
+	{
+		r->SentPacketAcknowledged();
+		return;
+	}
+	debugPrintf("Network SentPacketAcknowledged: didn't find hs=%08x\n", (unsigned int)hs);
+}
+
+void Network::ConnectionError(void* hs)
+{
+	// h points to an http state block that the caller is about to release, so we need to stop referring to it.
+	debugPrintf("Network: ConnectionError\n");
+
+	// See if it's a ready transaction
+	NetRing* r = readyTransactions;
+	while (r != NULL && r->hs == hs)
+	{
+		r = r->next;
+	}
+	if (r != NULL)
+	{
+		r->SetConnectionLost();
+		return;
+	}
+
+	// See if we were sending it
+	r = writingTransactions;
+	while (r != NULL && r->hs == hs)
+	{
+		r = r->next;
+	}
+	if (r != NULL)
+	{
+		r->SetConnectionLost();
+		return;
+	}
+
+	// See if we were closing it
+	r = closingTransactions;
+	while (r != NULL && r->hs == hs)
+	{
+		r = r->next;
+	}
+	if (r != NULL)
+	{
+		r->SetConnectionLost();
+		return;
+	}
+
+	// Else we didn't identify the transaction - maybe we already asked to close it
+	debugPrintf("Network ConnectionError: didn't find hs=%08x\n", (unsigned int)hs);
+}
+
+void Network::ReceiveInput(const char* data, int length, void* pcb, void* hs)
+{
+	NetRing* r = freeTransactions;
+	if (r == NULL)
+	{
+		reprap.GetPlatform()->Message(HOST_MESSAGE, "Network::ReceiveInput() - no free transactions!\n");
+		return;
+	}
+
+	freeTransactions = r->next;
+
+	r->Set(data, length, pcb, hs);
+	AppendTransaction(&readyTransactions, r);
+//	debugPrintf("Network - input received\n");
+}
+
+// Send the output data we already have, optionally with a file appended, then close the connection.
+// The file may be too large for our buffer, so we may have to send it in multiple transactions.
+void Network::SendAndClose(FileStore *f)
+{
+	NetRing *r = readyTransactions;
+	if (r != NULL)
+	{
+		readyTransactions = r->next;
+		if (r->LostConnection())
+		{
+			if (f != NULL)
+			{
+				f->Close();
+			}
+			AppendTransaction(&freeTransactions, r);
+			debugPrintf("Conn lost before send\n");
+		}
+		else
+		{
+			r->fileBeingSent = f;
+			AppendTransaction(&writingTransactions, r);
+//debug
+//			r->outputBuffer[r->outputPointer] = 0;
+//			debugPrintf("Transaction queued for writing to network, file=%c, data=%s\n", (f ? 'Y' : 'N'), r->outputBuffer);
+		}
+	}
+}
+
+//queries the PHY for link status, true = link is up, false, link is down or there is some other error
+bool Network::LinkIsUp()
+{
+	return status_link_up();
+}
+
+bool Network::Active() const
+{
+	return active;
+}
+
+
+// NetRing class members
+NetRing::NetRing(NetRing* n) : next(n)
+{
+}
+
+void NetRing::Set(const char* d, int l, void* pc, void* h)
+{
+	pcb = pc;
+	hs = h;
+	inputData = d;
+	inputLength = l;
+	inputPointer = 0;
+	outputPointer = 0;
+	sentPacketsOutstanding = 0;
+	fileBeingSent = NULL;
+}
+
+// Webserver calls this to read bytes that have come in from the network
+
+bool NetRing::Read(char& b)
+{
+	if (LostConnection() || inputPointer >= inputLength)
+	{
+		return false;
+	}
+
+	b = inputData[inputPointer];
+	inputPointer++;
+	return true;
+}
+
+// Webserver calls this to write bytes that need to go out to the network
+
+void NetRing::Write(char b)
+{
+	if (LostConnection()) return;
+
+	if (outputPointer >= ARRAY_SIZE(outputBuffer))
+	{
+		reprap.GetPlatform()->Message(HOST_MESSAGE, "Network::Write(char b) - Output buffer overflow! \n");
+		return;
+	}
+
+	// Add the byte to the buffer
+
+	outputBuffer[outputPointer] = b;
+	outputPointer++;
+}
+
+// This is not called for data, only for internally-
+// generated short strings at the start of a transmission,
+// so it should never overflow the buffer (which is checked
+// anyway).
+
+void NetRing::Write(const char* s)
+{
+	while (*s)
+	{
+		Write(*s++);
+	}
+}
+
+// Send some data if we can, returning true if all data has been sent
+bool NetRing::TrySendData()
+{
+	if (LostConnection())
+	{
+		return true;
+	}
+
+	if (!RepRapNetworkCanSend(hs))
+	{
+//		debugPrintf("Send busy\n");
+		return false;
+	}
+
+	if (sentPacketsOutstanding >= windowedSendPackets)
+	{
+//		debugPrintf("Awaiting ack\n");
+		return false;		// still waiting for earlier packets to be acknowledged
+	}
+
+	if (fileBeingSent != NULL)
+	{
+		while (outputPointer < ARRAY_SIZE(outputBuffer))
+		{
+			bool ok = fileBeingSent->Read(outputBuffer[outputPointer]);
+			if (!ok)
+			{
+				fileBeingSent->Close();
+				fileBeingSent = NULL;
+				break;
+			}
+			++outputPointer;
+		}
+//		debugPrintf("Read from file\n");
+	}
+
+	if (outputPointer == 0)
+	{
+//		debugPrintf("All data sent\n");
+		return true;
+//		return sentPacketsOutstanding == 0;		// no more data to send, so tell caller to close file if all packets acknowledged
+	}
+	else
+	{
+//		debugPrintf("Sending data, hs=%08x,  length=%d\n", (unsigned int)hs, outputPointer);
+		++sentPacketsOutstanding;
+		RepRapNetworkSendOutput(outputBuffer, outputPointer, pcb, hs);
+		outputPointer = 0;
+		return false;
+	}
+}
+
+void NetRing::SentPacketAcknowledged()
+{
+	if (sentPacketsOutstanding != 0)
+	{
+		--sentPacketsOutstanding;
+	}
+}
+
+// Close this connection. Return true if it really is closed, false if it needs to go in the deferred close list.
+bool NetRing::Close()
+{
+	if (LostConnection())
+	{
+		return true;
+	}
+
+//	debugPrintf("Closing connection hs=%08x\n", (unsigned int)hs);
+	RepRapNetworkSendOutput((char*) NULL, 0, pcb, hs);
+	return true;		// try not using deferred close for now
+}
+
+void NetRing::SetConnectionLost()
+{
+	hs = NULL;
+}
+
+bool NetRing::LostConnection() const
+{
+	return hs == NULL;
+}
+
+
+// End

Network.h

@@ -0,0 +1,104 @@
+/****************************************************************************************************
+
+RepRapFirmware - Network: RepRapPro Ormerod with Duet controller
+
+Separated out from Platform.h by dc42
+
+****************************************************************************************************/
+
+#ifndef NETWORK_H
+#define NETWORK_H
+
+#include <stdio.h>
+#include <ctype.h>
+#include <string.h>
+#include <malloc.h>
+#include <stdlib.h>
+#include <limits.h>
+
+// Platform-specific includes
+
+#include "Arduino.h"
+#include "ethernet_sam.h"
+
+// This class handles the network - typically an Ethernet.
+
+// The size of the http output buffer is critical to getting fast load times in the browser.
+// If this value is less than the TCP MSS, then Chrome under Windows will delay ack messages by about 120ms,
+// which results in very slow page loading. Any value higher than that will cause the TCP packet to be split
+// into multiple transmissions, which avoids this behaviour. Using a value of twice the MSS is most efficient because
+// each TCP packet will be full.
+// Currently we set the MSS (in file network/lwipopts.h) to 1432 which matches the value used by most versions of Windows
+// and therefore avoids additional memory use and fragmentation.
+const unsigned int httpOutputBufferSize = 2 * 1432;
+
+// Start with a ring buffer to hold input from the network that needs to be responded to.
+
+class NetRing
+{
+public:
+	friend class Network;
+
+protected:
+	NetRing(NetRing* n);
+	void Set(const char* d, int l, void* pc, void* h);
+	bool Read(char& b);
+	void SentPacketAcknowledged();
+	void Write(char b);
+	void Write(const char* s);
+	bool Close();
+	bool TrySendData();
+	void SetConnectionLost();
+	bool LostConnection() const;
+
+private:
+	void Reset();
+	void* pcb;
+	void* hs;
+
+	NetRing* next;
+	const char* inputData;
+	int inputLength;
+	int inputPointer;
+	uint8_t sentPacketsOutstanding;		// count of TCP packets we have sent that have not been acknowledged
+	char outputBuffer[httpOutputBufferSize];
+	int outputPointer;
+	bool closePending;
+	FileStore *fileBeingSent;
+	float closeRequestedTime;
+};
+
+// The main network class that drives the network.
+
+class Network
+{
+public:
+
+	void ReceiveInput(const char* data, int length, void* pc, void* h);
+	void InputBufferReleased(void *hs, void* pb);
+	void SentPacketAcknowledged(void *hs);
+	void ConnectionError(void* h);
+	bool Active() const;
+	bool LinkIsUp();
+	bool Read(char& b);
+	void Write(char b);
+	void Write(const char* s);
+	void SendAndClose(FileStore *f);
+	bool HaveData() const;
+
+	Network();
+	void Init();
+	void Spin();
+
+private:
+
+	void AppendTransaction(NetRing** list, NetRing *r);
+
+	NetRing *freeTransactions;
+	NetRing *readyTransactions;
+	NetRing *writingTransactions;
+	NetRing *closingTransactions;
+	bool active;
+};
+
+#endif

Platform.cpp

@@ -286,7 +286,6 @@ void Platform::InitZProbe()
 {
 	zProbeOnFilter.Init();
 	zProbeOffFilter.Init();
-	ResetZProbeMinSum();
 
 	if (nvData.zProbeType == 1 || nvData.zProbeType == 2)
 	{
@@ -294,7 +293,7 @@ void Platform::InitZProbe()
 		digitalWrite(zProbeModulationPin, HIGH);	// enable the IR LED
 		SetZProbing(false);
 	}
-	else if (nvData.zProbeType == 3 || nvData.zProbeType == 4)
+	else if (nvData.zProbeType == 3)
 	{
 		pinMode(zProbeModulationPin, OUTPUT);
 		digitalWrite(zProbeModulationPin, LOW);	// enable the ultrasonic sensor
@@ -323,20 +322,7 @@ int Platform::ZProbe()
 		case 2:
 			// Modulated IR sensor. We assume that zProbeOnFilter and zprobeOffFilter average the same number of readings.
 			// Because of noise, it is possible to get a negative reading, so allow for this.
-			return (int) (((int32_t) zProbeOnFilter.GetSum() - (int32_t) zProbeOffFilter.GetSum())
-					/ (4 * numZProbeReadingsAveraged));
-
-		case 4:
-			// Ultrasonic sensor in differential mode. We assume that zProbeOnFilter and zprobeOffFilter average the same number of readings.
-			{
-				uint32_t sum = zProbeOnFilter.GetSum() + zProbeOffFilter.GetSum();
-				if (sum < zProbeMinSum)
-				{
-					zProbeMinSum = sum;
-				}
-				uint32_t total = zProbeOnFilter.GetSum() + zProbeOffFilter.GetSum();
-				return (int) ((total - zProbeMinSum) / (4 * numZProbeReadingsAveraged));
-			}
+			return (int) (((int32_t) zProbeOnFilter.GetSum() - (int32_t) zProbeOffFilter.GetSum()) / (4 * numZProbeReadingsAveraged));
 
 		default:
 			break;
@@ -355,17 +341,6 @@ int Platform::GetZProbeSecondaryValues(int& v1, int& v2)
 		case 2:		// modulated IR sensor
 			v1 = (int) (zProbeOnFilter.GetSum() / (4 * numZProbeReadingsAveraged));	// pass back the reading with IR turned on
 			return 1;
-		case 4:		// differential ultrasonic
-			{
-				uint32_t sum = zProbeOnFilter.GetSum() + zProbeOffFilter.GetSum();
-				if (sum < zProbeMinSum)
-				{
-					zProbeMinSum = sum;
-				}
-				v1 = (int) ((zProbeOnFilter.GetSum() + zProbeOffFilter.GetSum()) / (8 * numZProbeReadingsAveraged)); // pass back the raw reading
-				v2 = (int) (zProbeMinSum / (8 * numZProbeReadingsAveraged));				// pass back the minimum found
-			}
-			return 2;
 		default:
 			break;
 		}
@@ -386,7 +361,6 @@ float Platform::ZProbeStopHeight() const
 	case 2:
 		return nvData.irZProbeParameters.GetStopHeight(GetTemperature(0));
 	case 3:
-	case 4:
 		return nvData.ultrasonicZProbeParameters.GetStopHeight(GetTemperature(0));
 	default:
 		return 0;
@@ -395,7 +369,7 @@ float Platform::ZProbeStopHeight() const
 
 void Platform::SetZProbeType(int pt)
 {
-	int newZProbeType = (pt >= 0 && pt <= 4) ? pt : 0;
+	int newZProbeType = (pt >= 0 && pt <= 3) ? pt : 0;
 	if (newZProbeType != nvData.zProbeType)
 	{
 		nvData.zProbeType = newZProbeType;
@@ -413,7 +387,6 @@ bool Platform::GetZProbeParameters(struct ZProbeParameters& params) const
 		params = nvData.irZProbeParameters;
 		return true;
 	case 3:
-	case 4:
 		params = nvData.ultrasonicZProbeParameters;
 		return true;
 	default:
@@ -434,7 +407,6 @@ bool Platform::SetZProbeParameters(const struct ZProbeParameters& params)
 		}
 		return true;
 	case 3:
-	case 4:
 		if (nvData.ultrasonicZProbeParameters != params)
 		{
 			nvData.ultrasonicZProbeParameters = params;
@@ -459,15 +431,6 @@ void Platform::WriteNvData()
 
 void Platform::SetZProbing(bool starting)
 {
-	if (starting && nvData.zProbeType == 4)
-	{
-		ResetZProbeMinSum();	// look for a new minimum
-	}
-}
-
-void Platform::ResetZProbeMinSum()
-{
-	zProbeMinSum = adRangeReal * numZProbeReadingsAveraged * 2;
 }
 
 // Note: the use of floating point time will cause the resolution to degrade over time.
@@ -607,8 +570,7 @@ void Platform::DisableInterrupts()
 // 0.  Kick the watchdog.
 // 1.  Kick off a new ADC conversion.
 // 2.  Fetch and process the result of the last ADC conversion.
-// 3a. If the last ADC conversion was for the Z probe, toggle the modulation output if using a modulated IR sensor,
-//     or update the minimum reading if using an ultrasonic sensor in differential mode.
+// 3a. If the last ADC conversion was for the Z probe, toggle the modulation output if using a modulated IR sensor.
 // 3b. If the last ADC reading was a thermistor reading, check for an over-temperature situation and turn off the heater if necessary.
 //     We do this here because the usual polling loop sometimes gets stuck trying to send data to the USB port.
 
@@ -619,21 +581,19 @@ void Platform::Tick()
 #ifdef TIME_TICK_ISR
 	uint32_t now = micros();
 #endif
-	WDT_Restart(WDT);
+	WDT_Restart(WDT);			// kick the watchdog
 	switch (tickState)
 	{
 	case 1:			// last conversion started was a thermistor
 	case 3:
 		{
-			ThermistorAveragingFilter& currentFilter =
-					const_cast<ThermistorAveragingFilter&>(thermistorFilters[currentHeater]);
+			ThermistorAveragingFilter& currentFilter = const_cast<ThermistorAveragingFilter&>(thermistorFilters[currentHeater]);
 			currentFilter.ProcessReading(GetAdcReading(heaterAdcChannels[currentHeater]));
 			StartAdcConversion(zProbeAdcChannel);
 			if (currentFilter.IsValid())
 			{
 				uint32_t sum = currentFilter.GetSum();
-				if (sum < thermistorOverheatSums[currentHeater]
-						|| sum >= adDisconnectedReal * numThermistorReadingsAveraged)
+				if (sum < thermistorOverheatSums[currentHeater] || sum >= adDisconnectedReal * numThermistorReadingsAveraged)
 				{
 					// We have an over-temperature or bad reading from this thermistor, so turn off the heater
 					// NB - the SetHeater function we call does floating point maths, but this is an exceptional situation so we allow it
@@ -692,7 +652,7 @@ void Platform::Tick()
 /*static*/void Platform::StartAdcConversion(adc_channel_num_t chan)
 {
 	adc_enable_channel(ADC, chan);
-	adc_start(ADC );
+	adc_start(ADC);
 }
 
 // Convert an Arduino Due pin number to the corresponding ADC channel number
@@ -815,16 +775,25 @@ void Platform::ClassReport(char* className, float &lastTime)
 
 float Platform::GetTemperature(size_t heater) const
 {
-	// If the ADC reading is N then for an ideal ADC, the input voltage is at least N/(AD_RANGE + 1) and less than (N + 1)/(AD_RANGE + 1), times the analog reference.
-	// So we add 0.5 to to the reading to get a better estimate of the input. But first, recognise the special case of thermistor disconnected.
 	int rawTemp = GetRawTemperature(heater);
+
+	// If the ADC reading is N then for an ideal ADC, the input voltage is at least N/(AD_RANGE + 1) and less than (N + 1)/(AD_RANGE + 1), times the analog reference.
+	// So we add 0.5 to to the reading to get a better estimate of the input.
+
+	float reading = (float) rawTemp + 0.5;
+
+	// Recognise the special case of thermistor disconnected.
+	// For some ADCs, the high-end offset is negative, meaning that the ADC never returns a high enough value. We need to allow for this here.
+
+	const PidParameters& p = nvData.pidParams[heater];
+	if (p.adcHighOffset < 0)
+	{
+		rawTemp -= (int)p.adcHighOffset;
+	}
 	if (rawTemp >= adDisconnectedVirtual)
 	{
-		// Thermistor is disconnected
-		return ABS_ZERO;
+		return ABS_ZERO;		// thermistor is disconnected
 	}
-	float reading = (float) rawTemp + 0.5;
-	const PidParameters& p = nvData.pidParams[heater];
 
 	// Correct for the low and high ADC offsets
 	reading -= p.adcLowOffset;
@@ -872,8 +841,8 @@ EndStopHit Platform::Stopped(int8_t drive)
 		{
 			int zProbeVal = ZProbe();
 			int zProbeADValue =
-					(nvData.zProbeType == 3 || nvData.zProbeType == 4) ?
-							nvData.ultrasonicZProbeParameters.adcValue : nvData.irZProbeParameters.adcValue;
+					(nvData.zProbeType == 3) ? nvData.ultrasonicZProbeParameters.adcValue
+							: nvData.irZProbeParameters.adcValue;
 			if (zProbeVal >= zProbeADValue)
 				return lowHit;
 			else if (zProbeVal * 10 >= zProbeADValue * 9)	// if we are at/above 90% of the target value
@@ -1390,411 +1359,4 @@ void Line::Spin()
 	}
 }
 
-//***************************************************************************************************
-
-// Network/Ethernet class
-
-// C calls to interface with LWIP (http://savannah.nongnu.org/projects/lwip/)
-// These are implemented in, and called from, a modified version of httpd.c
-// in the network directory.
-
-extern "C"
-{
-
-//void ResetEther();
-
-// Transmit data to the Network
-
-void RepRapNetworkSendOutput(char* data, int length, void* pbuf, void* pcb, void* hs);
-
-// When lwip releases storage, set the local copy of the pointer to 0 to stop
-// it being used again.
-
-void RepRapNetworkInputBufferReleased(void* pb)
-{
-	reprap.GetPlatform()->GetNetwork()->InputBufferReleased(pb);
-}
-
-void RepRapNetworkConnectionError(void* h)
-{
-	reprap.GetPlatform()->GetNetwork()->ConnectionError(h);
-	reprap.GetWebserver()->ConnectionError();
-}
-
-// Called to put out a message via the RepRap firmware.
-
-void RepRapNetworkMessage(char* s)
-{
-	reprap.GetPlatform()->Message(HOST_MESSAGE, s);
-}
-
-// Called to push data into the RepRap firmware.
-
-void RepRapNetworkReceiveInput(char* data, int length, void* pbuf, void* pcb, void* hs)
-{
-	reprap.GetPlatform()->GetNetwork()->ReceiveInput(data, length, pbuf, pcb, hs);
-}
-
-// Called when transmission of outgoing data is complete to allow
-// the RepRap firmware to write more.
-
-void RepRapNetworkSentPacketAcknowledged()
-{
-	reprap.GetPlatform()->GetNetwork()->SentPacketAcknowledged();
-}
-
-bool RepRapNetworkHasALiveClient()
-{
-	return reprap.GetPlatform()->GetNetwork()->Status() & clientLive;
-}
-
-}	// extern "C"
-
-Network::Network()
-{
-	active = false;
-	ethPinsInit();
-
-	//ResetEther();
-
-	// Construct the ring buffer
-
-	netRingAddPointer = new NetRing(NULL);
-	netRingGetPointer = netRingAddPointer;
-	for (int8_t i = 1; i < HTTP_STATE_SIZE; i++)
-		netRingGetPointer = new NetRing(netRingGetPointer);
-	netRingAddPointer->SetNext(netRingGetPointer);
-}
-
-// Reset the network to its disconnected and ready state.
-
-void Network::Reset()
-{
-	//reprap.GetPlatform()->Message(HOST_MESSAGE, "Reset.\n");
-	inputPointer = 0;
-	inputLength = -1;
-	outputPointer = 0;
-	writeEnabled = false;
-	closePending = false;
-	status = nothing;
-	sentPacketsOutstanding = 0;
-}
-
-void Network::CleanRing()
-{
-	for (int8_t i = 0; i <= HTTP_STATE_SIZE; i++)
-	{
-		netRingGetPointer->Free();
-		netRingGetPointer = netRingGetPointer->Next();
-	}
-	netRingAddPointer = netRingGetPointer;
-}
-
-void Network::Init()
-{
-	CleanRing();
-	Reset();
-
-	init_ethernet(reprap.GetPlatform()->IPAddress(), reprap.GetPlatform()->NetMask(), reprap.GetPlatform()->GateWay());
-	active = true;
-	sentPacketsOutstanding = 0;
-}
-
-void Network::Spin()
-{
-	if (!active)
-	{
-		//ResetEther();
-		return;
-	}
-
-	// Keep the Ethernet running
-
-	ethernet_task();
-
-	// Anything come in from the network to act on?
-
-	if (!netRingGetPointer->Active())
-		return;
-
-	// Finished reading the active ring element?
-
-	if (!netRingGetPointer->ReadFinished())
-	{
-		// No - Finish reading any data that's been received.
-
-		if (inputPointer < inputLength)
-			return;
-
-		// Haven't started reading it yet - set that up.
-
-		inputPointer = 0;
-		inputLength = netRingGetPointer->Length();
-		inputBuffer = netRingGetPointer->Data();
-	}
-}
-
-// Webserver calls this to read bytes that have come in from the network
-
-bool Network::Read(char& b)
-{
-	if (inputPointer >= inputLength)
-	{
-		inputLength = -1;
-		inputPointer = 0;
-		netRingGetPointer->SetReadFinished(); // Past tense...
-		SetWriteEnable(true);
-		//reprap.GetPlatform()->Message(HOST_MESSAGE, "Network - data read.\n");
-		return false;
-	}
-	b = inputBuffer[inputPointer];
-	inputPointer++;
-	return true;
-}
-
-// Webserver calls this to write bytes that need to go out to the network
-
-void Network::Write(char b)
-{
-	// Check for horrible things...
-
-	if (!CanWrite())
-	{
-		reprap.GetPlatform()->Message(HOST_MESSAGE, "Network::Write(char b) - Attempt to write when disabled.\n");
-		return;
-	}
-
-	if (outputPointer >= ARRAY_SIZE(outputBuffer))
-	{
-		reprap.GetPlatform()->Message(HOST_MESSAGE, "Network::Write(char b) - Output buffer overflow! \n");
-		return;
-	}
-
-	// Add the byte to the buffer
-
-	outputBuffer[outputPointer] = b;
-	outputPointer++;
-
-	// Buffer full?  If so, send it.
-
-	if (outputPointer == ARRAY_SIZE(outputBuffer))
-	{
-#if WINDOWED_SEND_PACKETS > 1
-		++sentPacketsOutstanding;
-#else
-		SetWriteEnable(false);  // Stop further writing from Webserver until the network tells us that this has gone
-#endif
-		RepRapNetworkSendOutput(outputBuffer, outputPointer, netRingGetPointer->Pbuf(), netRingGetPointer->Pcb(),
-				netRingGetPointer->Hs());
-		outputPointer = 0;
-	}
-}
-
-void Network::InputBufferReleased(void* pb)
-{
-	if (netRingGetPointer->Pbuf() != pb)
-	{
-		reprap.GetPlatform()->Message(HOST_MESSAGE, "Network::InputBufferReleased() - Pointers don't match!\n");
-		return;
-	}
-	netRingGetPointer->ReleasePbuf();
-}
-
-void Network::ConnectionError(void* h)
-{
-	// h points to an http state block that the caller is about to release, so we need to stop referring to it.
-	// The state block is usually but not always in use by the current http request being processed, in which case we abandon the current request.
-	if (netRingGetPointer != netRingAddPointer && netRingGetPointer->Hs() == h)
-	{
-		netRingGetPointer->Free();
-		netRingGetPointer = netRingGetPointer->Next();
-	}
-
-	// Reset the network layer. In particular, this clears the output buffer to make sure nothing more gets sent,
-	// and sets status to 'nothing' so that we can accept another connection attempt.
-	Reset();
-}
-
-void Network::ReceiveInput(char* data, int length, void* pbuf, void* pcb, void* hs)
-{
-	status = clientLive;
-	if (netRingAddPointer->Active())
-	{
-		reprap.GetPlatform()->Message(HOST_MESSAGE, "Network::ReceiveInput() - Ring buffer full!\n");
-		return;
-	}
-	netRingAddPointer->Set(data, length, pbuf, pcb, hs);
-	netRingAddPointer = netRingAddPointer->Next();
-	//reprap.GetPlatform()->Message(HOST_MESSAGE, "Network - input received.\n");
-}
-
-bool Network::CanWrite() const
-{
-#if WINDOWED_SEND_PACKETS > 1
-	return writeEnabled && sentPacketsOutstanding < WINDOWED_SEND_PACKETS;
-#else
-	return writeEnabled;
-#endif
-}
-
-void Network::SetWriteEnable(bool enable)
-{
-	writeEnabled = enable;
-	if (!writeEnabled)
-		return;
-	if (closePending)
-		Close();
-}
-
-void Network::SentPacketAcknowledged()
-{
-#if WINDOWED_SEND_PACKETS > 1
-	if (sentPacketsOutstanding != 0)
-	{
-		--sentPacketsOutstanding;
-	}
-	if (closePending && sentPacketsOutstanding == 0)
-	{
-		Close();
-	}
-#else
-	SetWriteEnable(true);
-#endif
-}
-
-// This is not called for data, only for internally-
-// generated short strings at the start of a transmission,
-// so it should never overflow the buffer (which is checked
-// anyway).
-
-void Network::Write(const char* s)
-{
-	int i = 0;
-	while (s[i])
-		Write(s[i++]);
-}
-
-void Network::Close()
-{
-	if (Status() && clientLive)
-	{
-		if (outputPointer > 0)
-		{
-			SetWriteEnable(false);
-			RepRapNetworkSendOutput(outputBuffer, outputPointer, netRingGetPointer->Pbuf(), netRingGetPointer->Pcb(),
-					netRingGetPointer->Hs());
-			outputPointer = 0;
-			closePending = true;
-			return;
-		}
-		RepRapNetworkSendOutput((char*) NULL, 0, netRingGetPointer->Pbuf(), netRingGetPointer->Pcb(),
-				netRingGetPointer->Hs());
-		netRingGetPointer->Free();
-		netRingGetPointer = netRingGetPointer->Next();
-		//reprap.GetPlatform()->Message(HOST_MESSAGE, "Network - output sent and closed.\n");
-	}
-	else
-		reprap.GetPlatform()->Message(HOST_MESSAGE, "Network::Close() - Attempt to close a closed connection!\n");
-	closePending = false;
-	status = nothing;
-	//Reset();
-}
-
-int8_t Network::Status() const
-{
-	if (inputPointer >= inputLength)
-		return status;
-	return status | clientConnected | byteAvailable;
-}
-
-NetRing::NetRing(NetRing* n)
-{
-	next = n;
-	Free();
-}
-
-void NetRing::Free()
-{
-	pbuf = 0;
-	pcb = 0;
-	hs = 0;
-	data = "";
-	length = 0;
-	read = false;
-	active = false;
-}
-
-bool NetRing::Set(char* d, int l, void* pb, void* pc, void* h)
-{
-	if (active)
-		return false;
-	pbuf = pb;
-	pcb = pc;
-	hs = h;
-	data = d;
-	length = l;
-	read = false;
-	active = true;
-	return true;
-}
-
-NetRing* NetRing::Next()
-{
-	return next;
-}
-
-char* NetRing::Data()
-{
-	return data;
-}
-
-int NetRing::Length()
-{
-	return length;
-}
-
-bool NetRing::ReadFinished()
-{
-	return read;
-}
-
-void NetRing::SetReadFinished()
-{
-	read = true;
-}
-
-bool NetRing::Active()
-{
-	return active;
-}
-
-void NetRing::SetNext(NetRing* n)
-{
-	next = n;
-}
-
-void* NetRing::Pbuf()
-{
-	return pbuf;
-}
-
-void NetRing::ReleasePbuf()
-{
-	pbuf = 0;
-}
-
-void* NetRing::Pcb()
-{
-	return pcb;
-}
-
-void* NetRing::Hs()
-{
-	return hs;
-}
-
-void NetRing::ReleaseHs()
-{
-	hs = 0;
-}
-
+// End

Platform.h

@@ -101,7 +101,7 @@ const unsigned int numZProbeReadingsAveraged = 8;	// we average this number of r
 #define MAX_FEEDRATES {50.0, 50.0, 3.0, 16.0}    // mm/sec
 #define ACCELERATIONS {800.0, 800.0, 10.0, 250.0}    // mm/sec^2
 #define DRIVE_STEPS_PER_UNIT {87.4890, 87.4890, 4000.0, 420.0}
-#define INSTANT_DVS {15.0, 15.0, 0.2, 2.0}    // (mm/sec)
+#define INSTANT_DVS {10.0, 10.0, 0.2, 2.0}    // (mm/sec)
 
 // AXES
 
@@ -212,21 +212,12 @@ const unsigned int adDisconnectedVirtual = adDisconnectedReal << adOversampleBit
  
 #define CLIENT_CLOSE_DELAY 0.002
 
-#define HTTP_STATE_SIZE 5
+#define HTTP_STATE_SIZE 7
 
 #define IP_ADDRESS {192, 168, 1, 10} // Need some sort of default...
 #define NET_MASK {255, 255, 255, 0}
 #define GATE_WAY {192, 168, 1, 1}
 
-// The size of the http output buffer is critical to getting fast load times in the browser.
-// If this value is less than the TCP MSS, then Chrome under Windows will delay ack messages by about 120ms,
-// which results in very slow page loading. Any value higher than that will cause the TCP packet to be split
-// into multiple transmissions, which avoids this behaviour. Using a value of twice the MSS is most efficient because
-// each TCP packet will be full.
-// Currently we set the MSS (in file network/lwipopts.h) to 1432 which matches the value used by most versions of Windows
-// and therefore avoids additional memory use and fragmentation.
-const unsigned int httpOutputBufferSize = 2 * 1432;
-
 
 /****************************************************************************************************/
 
@@ -263,103 +254,6 @@ enum IOStatus
   clientConnected = 8
 };
 
-//// All IO is done by classes derived from this class.
-//
-//class InputOutput
-//{
-//public:
-//	void TakeInputFrom(InputOutput* altIp);
-//	void SendOutputTo(InputOutput* altOp);
-//
-//protected:
-//	InputOutput* alternateInput;
-//	InputOutput* alternateOutput;
-//};
-
-// This class handles the network - typically an Ethernet.
-
-// Start with a ring buffer to hold input from the network
-// that needs to be responded to.
-
-class NetRing
-{
-public:
-	friend class Network;
-
-protected:
-	NetRing(NetRing* n);
-	NetRing* Next();
-	bool Set(char* d, int l, void* pb, void* pc, void* h);
-	char* Data();
-	int Length();
-	bool ReadFinished();
-	void SetReadFinished();
-	void* Pbuf();
-	void* Pcb();
-	void* Hs();
-	bool Active();
-	void Free();
-	void SetNext(NetRing* n);
-	void ReleasePbuf();
-	void ReleaseHs();
-
-private:
-	void Reset();
-	void* pbuf;
-	void* pcb;
-	void* hs;
-	char* data;
-	int length;
-	bool read;
-	bool active;
-	NetRing* next;
-};
-
-// The main network class that drives the network.
-
-class Network //: public InputOutput
-{
-public:
-
-	int8_t Status() const; // Returns OR of IOStatus
-	bool Read(char& b);
-	bool CanWrite() const;
-	void SetWriteEnable(bool enable);
-	void SentPacketAcknowledged();
-	void Write(char b);
-	void Write(const char* s);
-	void Close();
-	void ReceiveInput(char* data, int length, void* pb, void* pc, void* h);
-	void InputBufferReleased(void* pb);
-	void ConnectionError(void* h);
-	bool Active() const;
-	bool LinkIsUp();
-
-friend class Platform;
-
-protected:
-
-	Network();
-	void Init();
-	void Spin();
-
-private:
-
-	void Reset();
-	void CleanRing();
-	char* inputBuffer;
-	char outputBuffer[httpOutputBufferSize];
-	int inputPointer;
-	int inputLength;
-	int outputPointer;
-	bool writeEnabled;
-	bool closePending;
-	int8_t status;
-	NetRing* netRingGetPointer;
-	NetRing* netRingAddPointer;
-	bool active;
-	uint8_t sentPacketsOutstanding;		// count of TCP packets we have sent that have not been acknowledged
-};
 
 // This class handles serial I/O - typically via USB
 
@@ -722,7 +616,6 @@ private:
   
   void InitialiseInterrupts();
   int GetRawZHeight() const;
-  void ResetZProbeMinSum();
 
 // DRIVES
 
@@ -747,7 +640,6 @@ private:
   volatile ZProbeAveragingFilter zProbeOnFilter;					// Z probe readings we took with the IR turned on
   volatile ZProbeAveragingFilter zProbeOffFilter;					// Z probe readings we took with the IR turned off
   volatile ThermistorAveragingFilter thermistorFilters[HEATERS];	// bed and extruder thermistor readings
-  uint32_t zProbeMinSum;											// minimum Z probe sums seen, used with ultrasonic probe
 
 // AXES
 
@@ -1088,17 +980,5 @@ inline void Platform::PopMessageIndent()
 
 //***************************************************************************************
 
-//queries the PHY for link status, true = link is up, false, link is down or there is some other error
-inline bool Network::LinkIsUp()
-{
-	return status_link_up();
-}
-
-inline bool Network::Active() const
-{
-	return active;
-}
-
-
 
 #endif

RepRapFirmware.cpp

@@ -304,6 +304,17 @@ void RepRap::SetDebug(int d)
 
 char scratchString[STRING_LENGTH];
 
+// For debug use
+void debugPrintf(const char* fmt, ...)
+{
+	va_list p;
+	va_start(p, fmt);
+	vsnprintf(scratchString, ARRAY_SIZE(scratchString), fmt, p);
+	va_end(p);
+	scratchString[ARRAY_SIZE(scratchString) - 1] = 0;
+	reprap.GetPlatform()->Message(HOST_MESSAGE, scratchString);
+}
+
 #if 0	// no longer used, we use snprinf or sncatf instead
 
 // Float to a string.

RepRapFirmware.h

@@ -27,12 +27,14 @@ Licence: GPL
 
 // Warn of what's to come, so we can use pointers to classes...
 
+class Network;
 class Platform;
 class Webserver;
 class GCodes;
 class Move;
 class Heat;
 class RepRap;
+class FileStore;
 
 // A single instance of the RepRap class contains all the others
 
@@ -40,8 +42,9 @@ extern RepRap reprap;
 
 // Functions and globals not part of any class
 
+void debugPrintf(const char* fmt, ...);
 int sncatf(char *dst, size_t len, const char* fmt, ...);
-#if 0	// n longer used
+#if 0	// no longer used
 char* ftoa(char *a, const float& f, int prec);
 #endif
 bool StringEndsWith(const char* string, const char* ending);
@@ -55,6 +58,7 @@ int StringContains(const char* string, const char* match);
 extern char scratchString[];
 
 #include "Configuration.h"
+#include "Network.h"
 #include "Platform.h"
 #include "Webserver.h"
 #include "GCodes.h"

Webserver.h

@@ -53,7 +53,6 @@ class Webserver
     void Diagnostics();
     void SetPassword(const char* pw);
     void SetName(const char* nm);
-    void ConnectionError();
     void HandleReply(const char *s, bool error);
     void AppendReply(const char* s);
 
@@ -61,11 +60,9 @@ class Webserver
   
     void ParseClientLine();
     void SendFile(const char* nameOfFileToSend);
-    bool WriteBytes();
     void ParseQualifier();
     void CheckPassword();
     void LoadGcodeBuffer(const char* gc, bool convertWeb);
-    void CloseClient();
     bool PrintHeadString();
     bool PrintLinkTable();
     void GetGCodeList();
@@ -84,8 +81,6 @@ class Webserver
     bool active;
     float lastTime;
     float longWait;
-    FileStore* fileBeingSent;
-    bool writing;
     bool receivingPost;
     char postBoundary[POST_LENGTH];
     int boundaryCount;  
@@ -94,8 +89,6 @@ class Webserver
     bool postSeen;
     bool getSeen;
     bool clientLineIsBlank;
-    float clientCloseTime;
-    bool needToCloseClient;
 
     char clientLine[STRING_LENGTH+2];	// 2 chars extra so we can append \n\0
     char clientRequest[STRING_LENGTH];
@@ -103,13 +96,12 @@ class Webserver
     char jsonResponse[STRING_LENGTH+1];
     char gcodeBuffer[gcodeBufLength];
     unsigned int gcodeReadIndex, gcodeWriteIndex;		// head and tail indices into gcodeBuffer
-    int jsonPointer;
     int clientLinePointer;
     bool gotPassword;
     char password[SHORT_STRING_LENGTH+1];
     char myName[SHORT_STRING_LENGTH+1];
     char gcodeReply[STRING_LENGTH+1];
-    uint16_t seq;	// reply sequence number, so that the client can tell if a reply is new or not
+    uint16_t seq;	// reply sequence number, so that the client can tell if a json reply is new or not
 };
 
 

network/httpd.c

@@ -61,21 +61,22 @@
 #include "lwip/src/include/lwip/tcp.h"
 #include "fs.h"
 
-struct http_state {
-  char *file;
-  u16_t left;
-  u8_t retries;
+struct http_state
+{
+	// Receive fields
+	struct pbuf *pb;
+	// Transmit fields
+	char *file;
+	u16_t left;
+	u8_t retries;
 };
 
-// Prototypes for the RepRap functions in Platform.cpp that we
-// need to call.
+// Prototypes for the RepRap functions in Platform.cpp that we need to call.
 
-void RepRapNetworkReceiveInput(char* ip, int length, void* pbuf, void* pcb, void* hs);
-void RepRapNetworkInputBufferReleased(void* pbuf);
-void RepRapNetworkConnectionError(void* h);
-void RepRapNetworkMessage(char* s);
-void RepRapNetworkSentPacketAcknowledged();
-bool RepRapNetworkHasALiveClient();
+void RepRapNetworkReceiveInput(const char* ip, int length, void* pcb, void* hs);
+void RepRapNetworkConnectionError(void* hs);
+void RepRapNetworkMessage(const char* s);
+void RepRapNetworkSentPacketAcknowledged(void *hs);
 
 // Sanity check on initialisations.
 
@@ -104,7 +105,7 @@ conn_err(void *arg, err_t err)
 static void
 close_conn(struct tcp_pcb *pcb, struct http_state *hs)
 {
-  //RepRapNetworkMessage("close_conn called.\n");
+//  RepRapNetworkMessage("close_conn called.\n");
   tcp_arg(pcb, NULL);
   tcp_sent(pcb, NULL);
   tcp_recv(pcb, NULL);
@@ -147,8 +148,6 @@ send_data(struct tcp_pcb *pcb, struct http_state *hs)
 	  tcp_output(pcb);
 	  hs->file += len;
 	  hs->left -= len;
-	  //if(hs->left <= 0)
-	  //		RepRapNetworkAllowWriting();
   } else
   {
 	  RepRapNetworkMessage("send_data: error\n");
@@ -160,18 +159,19 @@ send_data(struct tcp_pcb *pcb, struct http_state *hs)
 static err_t
 http_poll(void *arg, struct tcp_pcb *pcb)
 {
-  struct http_state *hs;
+  struct http_state *hs = arg;
 
-  hs = arg;
-
-  /*  printf("Polll\n");*/
-  if (hs == NULL) {
-    /*    printf("Null, close\n");*/
+  if (hs == NULL)
+  {
+	RepRapNetworkMessage("Null, abort\n");
     tcp_abort(pcb);
     return ERR_ABRT;
-  } else {
+  }
+  else
+  {
     ++hs->retries;
-    if (hs->retries == 4) {
+    if (hs->retries == 4)
+    {
       tcp_abort(pcb);
       return ERR_ABRT;
     }
@@ -186,12 +186,10 @@ http_poll(void *arg, struct tcp_pcb *pcb)
 static err_t
 http_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
 {
-  struct http_state *hs;
+  struct http_state *hs = arg;
 
   LWIP_UNUSED_ARG(len);
 
-  hs = arg;
-
   hs->retries = 0;
 
   //RepRapNetworkMessage("..sent\n");
@@ -199,10 +197,11 @@ http_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
   if (hs->left > 0)
   {
     send_data(pcb, hs);
-  } else
+  }
+  else
   {
 	  // See if there is more to send
-	  RepRapNetworkSentPacketAcknowledged();
+	  RepRapNetworkSentPacketAcknowledged(hs);
   }
 
   return ERR_OK;
@@ -210,26 +209,29 @@ http_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
 /*-----------------------------------------------------------------------------------*/
 
 
-// ReoRap calls this with data to send.
+// RepRap calls this with data to send.
 // A null transmission implies the end of the data to be sent.
 
-void RepRapNetworkSendOutput(char* data, int length, void* pb, void* pc, void* h)
+void RepRapNetworkSendOutput(char* data, int length, void* pc, void* h)
 {
-	struct pbuf* p = pb;
 	struct tcp_pcb* pcb = pc;
 	struct http_state* hs = h;
 
-	if(length <= 0)
+	if (hs == 0)
 	{
-		//tcp_output(pcb);
-		//pbuf_free(p);
-		close_conn(pcb, hs);
+		RepRapNetworkMessage("Attempt to write with null structure.\n");
 		return;
 	}
 
-	if(hs == 0)
+	if (hs->pb != NULL)
 	{
-		RepRapNetworkMessage("Attempt to write with null structure.\n");
+		pbuf_free(hs->pb);
+		hs->pb = NULL;
+	}
+
+	if (length <= 0)
+	{
+		close_conn(pcb, hs);
 		return;
 	}
 
@@ -237,30 +239,25 @@ void RepRapNetworkSendOutput(char* data, int length, void* pb, void* pc, void* h
 	hs->left = length;
 	hs->retries = 0;
 
-	if(pb != 0)
-	{
-		RepRapNetworkInputBufferReleased(p);
-		pbuf_free(p);
-	}
 	send_data(pcb, hs);
 
-	//if(hs->left <= 0)
-		//RepRapNetworkAllowWriting();
-
-	/* Tell TCP that we wish be to informed of data that has been
-	           successfully sent by a call to the http_sent() function. */
+	/* Tell TCP that we wish be to informed of data that has been successfully sent by a call to the http_sent() function. */
 
 	tcp_sent(pcb, http_sent);
 }
 
 
+// Return 1 if sending is OK, i.e. there is no send in progress, else 0
+int RepRapNetworkCanSend(void *arg)
+{
+	struct http_state *hs = arg;
+	return hs->left <= 0;
+}
+
 static err_t
 http_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
 {
-	int i;
-	struct http_state *hs;
-
-	hs = arg;
+	struct http_state *hs = arg;
 
 	if (err == ERR_OK && p != NULL)
 	{
@@ -269,16 +266,15 @@ http_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
 
 		if (hs->file == NULL)
 		{
-			RepRapNetworkReceiveInput(p->payload, p->len, p, pcb, hs);
-		} else
+			hs->pb = p;
+			RepRapNetworkReceiveInput(p->payload, p->len, pcb, hs);
+		}
+		else
 		{
+			// We are already sending data on this connection, so not expecting any messages on it
 			pbuf_free(p);
 		}
 	}
-
-	if (err == ERR_OK && p == NULL) {
-		close_conn(pcb, hs);
-	}
 	return ERR_OK;
 }
 /*-----------------------------------------------------------------------------------*/
@@ -288,12 +284,6 @@ http_accept(void *arg, struct tcp_pcb *pcb, err_t err)
 {
   struct http_state *hs;
 
-  // This is a bit nasty.  Fake an out of memory error to prevent new page
-  // requests coming in while we are still sending the old ones.
-
-  if(RepRapNetworkHasALiveClient())
-	  return ERR_MEM;
-
   LWIP_UNUSED_ARG(arg);
   LWIP_UNUSED_ARG(err);
 
@@ -303,22 +293,22 @@ http_accept(void *arg, struct tcp_pcb *pcb, err_t err)
 
   hs = (struct http_state *)mem_malloc(sizeof(struct http_state));
 
-  if (hs == NULL) {
+  if (hs == NULL)
+  {
 	  RepRapNetworkMessage("Out of memory!\n");
-    return ERR_MEM;
+	  return ERR_MEM;
   }
 
   /* Initialize the structure. */
+  hs->pb = NULL;
   hs->file = NULL;
   hs->left = 0;
   hs->retries = 0;
 
-  /* Tell TCP that this is the structure we wish to be passed for our
-     callbacks. */
+  /* Tell TCP that this is the structure we wish to be passed for our callbacks. */
   tcp_arg(pcb, hs);
 
-  /* Tell TCP that we wish to be informed of incoming data by a call
-     to the http_recv() function. */
+  /* Tell TCP that we wish to be informed of incoming data by a call to the http_recv() function. */
   tcp_recv(pcb, http_recv);
 
   tcp_err(pcb, conn_err);
@@ -326,6 +316,7 @@ http_accept(void *arg, struct tcp_pcb *pcb, err_t err)
   tcp_poll(pcb, http_poll, 4);
   return ERR_OK;
 }
+
 /*-----------------------------------------------------------------------------------*/
 
 // This function (is)x should be called only once at the start.
@@ -337,7 +328,9 @@ httpd_init(void)
 
   initCount++;
   if(initCount > 1)
+  {
 	  RepRapNetworkMessage("httpd_init() called more than once.\n");
+  }
 
   pcb = tcp_new();
   tcp_bind(pcb, IP_ADDR_ANY, 80);

network/lwipopts.h

@@ -104,7 +104,7 @@ a lot of data that needs to be copied, this should be set high. */
 #define MEMP_NUM_UDP_PCB        4
 
 /* MEMP_NUM_TCP_PCB: the number of simultaneously active TCP connections. */
-#define MEMP_NUM_TCP_PCB        2
+#define MEMP_NUM_TCP_PCB        6
 /* MEMP_NUM_TCP_PCB_LISTEN: the number of listening TCP connections. */
 #define MEMP_NUM_TCP_PCB_LISTEN 1
 /* MEMP_NUM_TCP_SEG: the number of simultaneously queued TCP segments. */