//	Altirra - Atari 800/800XL/5200 emulator
//	Copyright (C) 2009-2011 Avery Lee
//
//	This program is free software; you can redistribute it and/or modify
//	it under the terms of the GNU General Public License as published by
//	the Free Software Foundation; either version 2 of the License, or
//	(at your option) any later version.
//
//	This program is distributed in the hope that it will be useful,
//	but WITHOUT ANY WARRANTY; without even the implied warranty of
//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//	GNU General Public License for more details.
//
//	You should have received a copy of the GNU General Public License
//	along with this program; if not, write to the Free Software
//	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

#include "stdafx.h"
#include "modem.h"
#include "scheduler.h"
#include "uirender.h"
#include "console.h"
#include "debuggerlog.h"

ATDebuggerLogChannel g_ATLCModem(false, false, "MODEM", "Modem activity");
ATDebuggerLogChannel g_ATLCModemTCP(false, false, "MODEMTCP", "Modem TCP/IP activity");

namespace {
	enum {
		// 1.0s guard time
		kGuardTime = 7159090 / 4,
		kCommandTimeout = 7159090 * 30 / 4,

		// 0.125s delay after a command completes
		kCommandTermDelay = 7159090 / 32,

		// two seconds of ringing
		kRingOnTime = 7159090 * 2 / 4,

		// four seconds of not ringing
		kRingOffTime = 7159090 * 4 / 4,
	};
}

ATModemRegisters::ATModemRegisters()
	: mAutoAnswerRings(0)
	, mEscapeChar('+')
	, mLineTermChar(0x0D)
	, mRespFormatChar(0x0A)
	, mCommandEditChar(0x08)
	, mDialToneWaitTime(2)
	, mDialCarrierWaitTime(50)
	, mLostCarrierWaitTime(14)
	, mEscapePromptDelay(50)
	, mbReportCarrier(true)
	, mDTRMode(2)
	, mbEchoMode(true)
	, mbQuietMode(false)
	, mbToneDialMode(true)
	, mbShortResponses(false)
	, mExtendedResultCodes(4)
	, mSpeakerVolume(0)
	, mSpeakerMode(0)
	, mGuardToneMode(0)
	, mbLoopbackMode(false)
{
}

ATModemEmulator::ATModemEmulator()
	: mpScheduler(NULL)
	, mpSlowScheduler(NULL)
	, mpDriver(NULL)
	, mpCB(NULL)
	, mpEventEnterCommandMode(NULL)
	, mpEventCommandModeTimeout(NULL)
	, mpEventCommandTermDelay(NULL)
	, mbInited(false)
	, mbCommandMode(false)
	, mbListenEnabled(false)
	, mbLoggingState(false)
	, mbRinging(false)
	, mCommandState(kCommandState_Idle)
	, mLostCarrierDelayCycles(0)
{
}

ATModemEmulator::~ATModemEmulator() {
	Shutdown();
}

void ATModemEmulator::Init(ATScheduler *sched, ATScheduler *slowsched, IATUIRenderer *uir) {
	mbInited = true;

	mpScheduler = sched;
	mpSlowScheduler = slowsched;
	mpUIRenderer = uir;
	mLastWriteTime = ATSCHEDULER_GETTIME(sched);
	mTransmitIndex = 0;
	mTransmitLength = 0;

	mDeviceTransmitReadOffset = 0;
	mDeviceTransmitWriteOffset = 0;
	mDeviceTransmitLevel = 0;
	mbDeviceTransmitUnderflow = true;

	mCommandLength = 0;
	mbCommandMode = true;
	mConnectionState = kConnectionState_NotConnected;
	mbListening = false;
	mbIncomingConnection = false;
	mbSuppressNoCarrier = false;
	mbConnectionFailed = false;
	mbNewConnectedState = 0;
	mConnectRate = 0;

	mRegisters = mSavedRegisters;
	UpdateDerivedRegisters();

	mpEventPoll = mpSlowScheduler->AddEvent(100, this, 3);

	UpdateControlState();
	RestoreListeningState();
}

void ATModemEmulator::Shutdown() {
	mpCB = NULL;

	TerminateCall();

	if (mpSlowScheduler) {
		if (mpEventPoll) {
			mpSlowScheduler->RemoveEvent(mpEventPoll);
			mpEventPoll = NULL;
		}

		mpSlowScheduler = NULL;
	}

	if (mpScheduler) {
		if (mpEventCommandTermDelay) {
			mpScheduler->RemoveEvent(mpEventCommandTermDelay);
			mpEventCommandTermDelay = NULL;
		}

		if (mpEventEnterCommandMode) {
			mpScheduler->RemoveEvent(mpEventEnterCommandMode);
			mpEventEnterCommandMode = NULL;
		}

		if (mpEventCommandModeTimeout) {
			mpScheduler->RemoveEvent(mpEventCommandModeTimeout);
			mpEventCommandModeTimeout = NULL;
		}

		mpScheduler = NULL;
	}

	if (mpUIRenderer) {
		mpUIRenderer->SetModemConnection(NULL);
		mpUIRenderer = NULL;
	}

	mbInited = false;
}

void ATModemEmulator::ColdReset() {
	if (mpEventCommandTermDelay) {
		mpScheduler->RemoveEvent(mpEventCommandTermDelay);
		mpEventCommandTermDelay = NULL;
	}

	if (mpEventEnterCommandMode) {
		mpScheduler->RemoveEvent(mpEventEnterCommandMode);
		mpEventEnterCommandMode = NULL;
	}

	if (mpEventCommandModeTimeout) {
		mpScheduler->RemoveEvent(mpEventCommandModeTimeout);
		mpEventCommandModeTimeout = NULL;
	}

	TerminateCall();

	mSavedRegisters = ATModemRegisters();
	mRegisters = mSavedRegisters;
	UpdateDerivedRegisters();
	UpdateControlState();

	RestoreListeningState();
	EnterCommandMode(false, true);
}

void ATModemEmulator::SetTerminalState(const ATRS232TerminalState& state) {
	const bool dtrdrop = mTerminalState.mbDataTerminalReady && !state.mbDataTerminalReady;

	mTerminalState = state;

	if (dtrdrop) {
		switch(mRegisters.mDTRMode) {
			default:	// 0 - ignore DTR
				break;

			case 1:		// 1 - drop to command mode on DTR drop
				EnterCommandMode(true, false);
				break;

			case 2:		// 2 - hang up on DTR drop; don't auto-answer
				if (mConnectionState) {
					mbSuppressNoCarrier = true;

					TerminateCall();
					RestoreListeningState();
					EnterCommandMode(true, false);
				}
				break;
		}
	}
}

ATRS232ControlState ATModemEmulator::GetControlState() {
	return mControlState;
}

void ATModemEmulator::SetConfig(const ATRS232Config& config) {
	mConfig = config;
	mbListenEnabled = (config.mListenPort != 0);

	if (mbListening && !mbListenEnabled)
		TerminateCall();
	else if (!mbListening && mbListenEnabled && !mConnectionState)
		RestoreListeningState();

	if (mpDriver)
		mpDriver->SetConfig(config);

	UpdateUIStatus();
}

bool ATModemEmulator::Read(uint32 baudRate, uint8& c, bool& framingError) {
	framingError = false;

	bool loggingState = g_ATLCModemTCP.IsEnabled();
	if (mbLoggingState != loggingState) {
		mbLoggingState = loggingState;

		if (mpDriver)
			mpDriver->SetLoggingEnabled(loggingState);
	}

	if (mTransmitIndex < mTransmitLength) {
		c = mTransmitBuffer[mTransmitIndex++];

		if (mTransmitIndex >= mTransmitLength) {
			mTransmitIndex = 0;
			mTransmitLength = 0;
		}

		return true;
	}

	if (mbCommandMode)
		return false;

	if (!mpDriver)
		return false;

	if (!mpDriver->Read(&c, 1))
		return false;

	VDStringA msgs;
	if (mpDriver->ReadLogMessages(msgs)) {
		VDStringA::size_type pos = 0;

		for(;;) {
			VDStringA::size_type term = msgs.find('\n', pos);

			if (term == VDStringA::npos)
				break;

			g_ATLCModemTCP("%.*s\n", term - pos, msgs.c_str() + pos);

			pos = term + 1;
		}
	}

	if (mConfig.mbRequireMatchedDTERate && abs((int)baudRate - (int)mConnectRate) > 1) {
		// baud rate mismatch -- return some bogus character and flag a framing error
		c = 'U';
		framingError = true;
	}

	return true;
}

void ATModemEmulator::Write(uint32 baudRate, uint8 c) {
	const uint32 t = ATSCHEDULER_GETTIME(mpScheduler);
	uint32 delay = t - mLastWriteTime;
	mLastWriteTime = t;

	if (mpEventCommandTermDelay)
		return;

	if (mbCommandMode) {
		c &= 0x7F;

		switch(mCommandState) {
			case kCommandState_Idle:
				if (mConfig.mDeviceMode == kATRS232DeviceMode_1030)
					break;

				if ((c & 0xdf) == 'A')
					mCommandState = kCommandState_A;
				break;

			case kCommandState_A:
				if ((c & 0xdf) == 'T')
					mCommandState = kCommandState_AT;
				else if (c == '/') {
					mCommandState = kCommandState_AT;
					mCommandLength = mLastCommand.size();
					mLastCommand.copy((char *)mCommandBuffer, mCommandLength);

					mpScheduler->SetEvent(kCommandTermDelay, this, 4, mpEventCommandTermDelay);
				} else
					mCommandState = kCommandState_Idle;
				break;

			case kCommandState_AT:
				if (c == mRegisters.mLineTermChar) {
					mpScheduler->SetEvent(kCommandTermDelay, this, 4, mpEventCommandTermDelay);
				} else if (c == mRegisters.mCommandEditChar) {
					// If the command buffer is empty, just dump the edit char. We don't even
					// echo it.
					if (!mCommandLength)
						return;

					--mCommandLength;

					// Conexant/3-79 [S5 - Command Line Editing Character] says this character
					// is echoed as edit, space, edit. Note that we'll be writing another edit char below.
					if (mRegisters.mbEchoMode) {
						if (mTransmitLength + 2 < sizeof mTransmitBuffer) {
							mTransmitBuffer[mTransmitLength++] = c;
							mTransmitBuffer[mTransmitLength++] = ' ';
						}
					}

					mpScheduler->SetEvent(kCommandTimeout, this, 2, mpEventCommandModeTimeout);
				} else {
					if (mCommandLength < sizeof mCommandBuffer)
						mCommandBuffer[mCommandLength++] = c;

					mpScheduler->SetEvent(kCommandTimeout, this, 2, mpEventCommandModeTimeout);
				}
				break;
		}

		if (mRegisters.mbEchoMode) {
			if (mTransmitLength < sizeof mTransmitBuffer)
				mTransmitBuffer[mTransmitLength++] = c;
		}
	} else {
		if ((c & 0x7f) == mRegisters.mEscapeChar && mConfig.mDeviceMode != kATRS232DeviceMode_1030) {
			if (delay >= kGuardTime || mGuardCharCounter) {
				if (++mGuardCharCounter >= 3)
					mpScheduler->SetEvent(kGuardTime, this, 1, mpEventEnterCommandMode);
			}
		} else {
			mGuardCharCounter = 0;

			if (mpEventEnterCommandMode) {
				mpScheduler->RemoveEvent(mpEventEnterCommandMode);
				mpEventEnterCommandMode = NULL;
			}
		}

		if (mConfig.mbRequireMatchedDTERate && abs((int)baudRate - (int)mConnectRate) > 1) {
			// baud rate mismatch -- send some bogus character
			c = 'U';
		}

		mMutex.Lock();
		if (mDeviceTransmitLevel < sizeof mDeviceTransmitBuffer) {
			mDeviceTransmitBuffer[mDeviceTransmitWriteOffset] = c;

			if (++mDeviceTransmitWriteOffset >= sizeof mDeviceTransmitBuffer)
				mDeviceTransmitWriteOffset = 0;

			++mDeviceTransmitLevel;

			if (mbDeviceTransmitUnderflow) {
				if (mpDriver)
					OnWriteAvail(mpDriver);
			}
		}
		mMutex.Unlock();
	}
}

void ATModemEmulator::SetToneDialingMode(bool enable) {
	mRegisters.mbToneDialMode = enable;
}

bool ATModemEmulator::IsToneDialingMode() const {
	return mRegisters.mbToneDialMode;
}

void ATModemEmulator::HangUp() {
	mbSuppressNoCarrier = true;

	TerminateCall();
	RestoreListeningState();
}

void ATModemEmulator::Dial(const char *address, const char *service) {
	TerminateCall();

	mbConnectionFailed = false;

	mAddress = address;
	mService = service;

	mpDriver = ATCreateModemDriverTCP();
	mpDriver->SetConfig(mConfig);
	if (!mpDriver->Init(mAddress.c_str(), mService.c_str(), 0, g_ATLCModemTCP.IsEnabled(), this)) {
		SendResponse(kResponseError);
		RestoreListeningState();
		return;
	}

	UpdateUIStatus();
}

void ATModemEmulator::Answer() {
	// It's an error if ATA is issued while in online state (Table 9/V.250).
	if (mConnectionState) {
		SendResponse(kResponseError);
		return;
	}
	
	// If we have a connection incoming, then we're already virtually connected
	// and should "answer" the connection. The connection state switching code
	// will issue the CONNECT banner.
	if (mbIncomingConnection) {
		mbListening = false;
		return;
	}

	// No incoming connection, so report NO CARRIER.
	SendResponse(kResponseNoCarrier);
}

void ATModemEmulator::FlushOutputBuffer() {
	mTransmitIndex = 0;
	mTransmitLength = 0;
}

void ATModemEmulator::Poll() {
	if (mpEventCommandTermDelay)
		return;

	if (mbConnectionFailed) {
		mbConnectionFailed = false;

		UpdateUIStatus();

		SendResponse(kResponseNoAnswer);

		EnterCommandMode(false, false);

		RestoreListeningState();
	} else {
		bool nowConnected = (mbNewConnectedState != 0);

		if (mbListening) {
			if (mbIncomingConnection != nowConnected) {
				mbIncomingConnection = nowConnected;

				if (nowConnected) {
					mLastRingTime = ATSCHEDULER_GETTIME(mpScheduler) - kRingOnTime;
					mbRinging = true;

					uint32 port;
					if (mpDriver->GetLastIncomingAddress(mAddress, port)) {
						mService.sprintf("%u", port);
					} else {
						mAddress = "<Unknown>";
						mService.clear();
					}

					UpdateUIStatus();
				} else {
					mbRinging = false;
					UpdateUIStatus();

					if (!mbCommandMode) {
						if (mbSuppressNoCarrier)
							mbSuppressNoCarrier = false;
						else
							SendResponse(kResponseNoCarrier);

						EnterCommandMode(false, false);
					}

					RestoreListeningState();
					UpdateControlState();
				}
			}

			if (mbIncomingConnection) {
				VDASSERT(mbCommandMode);

				// If DTR is low in AT&D2 mode, we should not auto-answer (level triggered).
				if (mRegisters.mAutoAnswerRings && (mRegisters.mDTRMode != 2 || mTerminalState.mbDataTerminalReady)) {
					mbListening = false;
					// we will fall through to connection code next
				} else if (mCommandLength == 0) {
					uint32 t = ATSCHEDULER_GETTIME(mpScheduler);

					if (t - mLastRingTime > (mbRinging ? (uint32)kRingOnTime : (uint32)kRingOffTime)) {
						mLastRingTime = t;

						if (mbRinging)
							SendResponse(kResponseRing);

						mbRinging = !mbRinging;
					}
				}
			}
		}
		
		// this is a separate clause so we can fall through on the same tick for auto-answer
		// above
		if (!mbListening) {
			if (mbRinging) {
				mbRinging = false;
				UpdateControlState();
			}

			switch(mConnectionState) {
				case kConnectionState_NotConnected:
					if (nowConnected) {
						mConnectionState = kConnectionState_Connected;

						mConnectRate = mConfig.mConnectionSpeed;
						if (!mConnectRate)
							mConnectRate = 9600;

						SendConnectResponse();

						mbCommandMode = false;
						mbSuppressNoCarrier = false;

						UpdateControlState();
						UpdateUIStatus();
					}
					break;

				case kConnectionState_Connected:
					if (!nowConnected) {
						mConnectionState = kConnectionState_LostCarrier;
						mLostCarrierTime = ATSCHEDULER_GETTIME(mpScheduler);

						UpdateControlState();
						UpdateUIStatus();
					}
					break;

				case kConnectionState_LostCarrier:
					if (nowConnected) {
						mConnectionState = kConnectionState_Connected;
						UpdateControlState();
					} else if (mLostCarrierDelayCycles && ATSCHEDULER_GETTIME(mpScheduler) - mLostCarrierTime > mLostCarrierDelayCycles) {
						TerminateCall();

						mConnectionState = kConnectionState_NotConnected;

						UpdateUIStatus();

						if (mbSuppressNoCarrier)
							mbSuppressNoCarrier = false;
						else
							SendResponse(kResponseNoCarrier);

						EnterCommandMode(false, false);

						if (mbListenEnabled)
							RestoreListeningState();

						UpdateControlState();
					}
					break;

			}
		}
	}
}

void ATModemEmulator::ParseCommand() {
	if (mpEventCommandModeTimeout) {
		mpScheduler->RemoveEvent(mpEventCommandModeTimeout);
		mpEventCommandModeTimeout = NULL;
	}

	uint32 len = mCommandLength;
	mCommandLength = 0;
	mCommandState = kCommandState_Idle;

	if (!len) {
		SendResponse(kResponseOK);
		return;
	}

	// store last command for A/; note that this happens even if there is an error,
	// in which case A/ also replays the error
	mLastCommand.assign((const char *)mCommandBuffer, (const char *)mCommandBuffer + len);

	g_ATLCModem("Executing command: [%s]\n", mLastCommand.c_str());

	const char *s = (const char *)mCommandBuffer;
	const char *t = (const char *)mCommandBuffer + len;

	for(;;) {
		// eat whitespace
		uint8 c;
		do {
			if (s == t) {
				SendResponse(kResponseOK);
				return;
			}

			c = *s++;
		} while(c == ' ');

		// capture command
		uint8 cmd = c;
		uint8 extcmd = 0;

		if (cmd == '&') {
			if (s != t) {
				extcmd = *s++;
				if ((uint8)(extcmd - 'a') < 26)
					extcmd &= ~0x20;
			}
		} else if ((uint8)(cmd - 'a') < 26)
			cmd &= ~0x20;

		// eat more whitespace
		while(s != t && *s == ' ')
			++s;

		// capture a number
		bool hasNumber = false;
		uint32 number = 0;

		if (cmd != 'D') {
			if (s != t && (uint8)(*s - (uint8)'0') < 10) {
				hasNumber = true;

				do {
					number *= 10;
					number += (*s - '0');

					++s;
					if (s == t)
						break;

					c = *s;
				} while((uint8)(*s - (uint8)'0') < 10);
			}
		}

		switch(cmd) {
			case '&':	// extended command
				switch(extcmd) {
					case 'C':	// &C - RLSD behavior
						if (!hasNumber)
							number = 0;

						if (number >= 2) {
							SendResponse(kResponseError);
							return;
						}

						mRegisters.mbReportCarrier = (number > 0);
						UpdateControlState();
						break;

					case 'D':	// &D - DTR behavior
						if (!hasNumber)
							number = 2;

						if (number >= 3) {
							SendResponse(kResponseError);
							return;
						}

						mRegisters.mDTRMode = number;
						break;

					case 'F':	// &F - Set to Factory-Defined Configuration
						mRegisters = ATModemRegisters();
						UpdateDerivedRegisters();
						break;

					case 'G':	// &G - Select Guard Tone
						if (!hasNumber)
							number = 0;

						if (number > 2) {
							SendResponse(kResponseError);
							return;
						}

						mRegisters.mGuardToneMode = number;
						break;

					case 'P':	// &P - Select Pulse Dial Make/Break Ratio (validated but ignored)
						if (hasNumber && number > 3) {
							SendResponse(kResponseError);
							return;
						}
						break;

					case 'T':	// &T - Local Analog Loopback Test
						if (!hasNumber)
							number = 0;

						mRegisters.mbLoopbackMode = (number != 0);
						break;

					case 'V':	// &V - Display Current Configuration and Stored Profile
						SendResponse("");
						SendResponse("ACTIVE PROFILE:");
						ReportRegisters(mRegisters, false);
						SendResponse("");
						SendResponse("STORED PROFILE 0:");
						ReportRegisters(mSavedRegisters, true);
						break;

					case 'W':	// &W - Store Current Configuration
						mSavedRegisters = mRegisters;
						break;

					default:
						SendResponse(kResponseError);
						return;
				}
				break;

			case 'A':	// answer
				Answer();
				return;

			case 'B':	// select communication standard (ignored)
				break;

			case 'D':
				// eat more whitespace
				while(s != t && *s == ' ')
					++s;

				if (s == t) {
					SendResponse(kResponseError);
					return;
				}

				// check if we are in online command state -- err out if so
				if (mConnectionState) {
					SendResponse(kResponseError);
					return;
				}

				// check if we allow outbound connections -- if not, return no dialtone
				if (!mConfig.mbAllowOutbound) {
					SendResponse(kResponseNoDialtone);
					return;
				}

				// check for 'I' to indicate IP-based dialing (for compatibility with Atari800)
				if (*s == 'I' || *s == 'i') {
					// parse out hostname and port
					++s;

					while(s != t && *s == ' ')
						++s;

					const char *hostname = s;

					while(s != t && *s != ' ')
						++s;

					const char *hostnameend = s;

					while(s != t && *s == ' ')
						++s;

					const char *servicename = "23";
					const char *servicenameend = servicename + 2;

					if (s != t) {
						servicename = s;

						while(s != t && *s != ' ')
							++s;

						servicenameend = s;
					}

					Dial(VDStringA(hostname, hostnameend).c_str(), VDStringA(servicename, servicenameend).c_str());
				} else if (!mConfig.mDialAddress.empty() && !mConfig.mDialService.empty()) {
					Dial(mConfig.mDialAddress.c_str(), mConfig.mDialService.c_str());
				} else {
					SendResponse(kResponseNoAnswer);
					return;
				}
				return;

			case 'E':	// echo (number)
				if (!hasNumber || number >= 2) {
					SendResponse(kResponseError);
					return;
				}

				mRegisters.mbEchoMode = (number != 0);
				break;

			case 'H':	// hook control (optional number)
				if (hasNumber && number >= 2) {
					SendResponse(kResponseError);
					return;
				}

				HangUp();
				break;

			case 'L':	// set speaker volume (ignored)
				if (!hasNumber || number >= 4) {
					SendResponse(kResponseError);
					return;
				}
				break;

			case 'M':	// speaker control
				if (!hasNumber || number >= 4) {
					SendResponse(kResponseError);
					return;
				}
				break;

			case 'O':	// on-hook
				if (!mConnectionState)
					SendResponse(kResponseError);
				else {
					SendConnectResponse();
					mbCommandMode = false;
					UpdateUIStatus();
				}
				return;

			case 'P':	// change dial mode default to pulse dial
				mRegisters.mbToneDialMode = false;
				break;

			case 'Q':	// quiet mode
				if (!hasNumber)
					number = 1;

				if (number >= 2) {
					SendResponse(kResponseError);
					return;
				}

				mRegisters.mbQuietMode = (number != 0);
				break;

			case '=':	// set/query register
			case 'S':	// set/query register
				{
					bool set = false;
					bool query = false;

					if (cmd == '=')
						query = true;
					else if (s != t) {
						if (*s == '=') {
							++s;

							set = true;
						} else if (*s == '?') {
							++s;

							query = true;
						}
					}

					if (hasNumber) {
						if (GetRegisterValue(number) < 0) {
							SendResponse(kResponseError);
							return;
						}

						mLastRegister = number;
					}

					if (query) {
						int v = GetRegisterValue(mLastRegister);

						if (mTransmitIndex <= sizeof mTransmitBuffer - 7) {
							if (!mRegisters.mbShortResponses) {
								mTransmitBuffer[mTransmitLength++] = mRegisters.mLineTermChar;
								mTransmitBuffer[mTransmitLength++] = mRegisters.mRespFormatChar;
							}

							mTransmitBuffer[mTransmitLength++] = (uint8)('0' + (v / 100)); v %= 100;
							mTransmitBuffer[mTransmitLength++] = (uint8)('0' + (v / 10)); v %= 10;
							mTransmitBuffer[mTransmitLength++] = (uint8)('0' + v);
							mTransmitBuffer[mTransmitLength++] = mRegisters.mLineTermChar;
							mTransmitBuffer[mTransmitLength++] = mRegisters.mRespFormatChar;
						}
					} else if (set) {
						if (s == t && (uint8)(*s - '0') >= 10) {
							SendResponse(kResponseError);
							return;
						}

						uint32 value = (*s++ - '0');

						while(s != t) {
							c = (uint8)(*s - '0');

							if (c >= 10)
								break;

							++s;

							value = (value * 10) + c;
						}

						if (!SetRegisterValue(mLastRegister, value)) {
							SendResponse(kResponseError);
							return;
						}
					}
				}
				break;

			case 'T':	// change dial mode default to tone dial
				mRegisters.mbToneDialMode = true;
				break;

			case 'V':	// verbose mode
				if (hasNumber && number >= 2) {
					SendResponse(kResponseError);
					return;
				}

				mRegisters.mbShortResponses = (number == 0);
				break;

			case 'X':	// extended result code mode
				if (!hasNumber || number >= 5) {
					SendResponse(kResponseError);
					return;
				}

				mRegisters.mExtendedResultCodes = number;
				break;

			case 'Z':	// reset modem (number optional)
				TerminateCall();
				mRegisters = mSavedRegisters;
				UpdateDerivedRegisters();
				RestoreListeningState();
				break;

			default:
				SendResponse(kResponseError);
				return;
		}
	}
}

void ATModemEmulator::SendConnectResponse() {
	if (mRegisters.mbQuietMode)
		return;

	const uint32 rate = mConfig.mConnectionSpeed;
	if (!mRegisters.mExtendedResultCodes) {
		SendResponse(kResponseConnect);
		return;
	}

	static const uint32 kBaudRates[]={
		300,
		600,
		1200,
		2400,
		4800,
		7200,
		9600,
		12000,
		14400,
		19200,
		38400,
		57600,
		115200,
		230400,
	};

	static const uint32 kResponseIds[]={
		kResponseConnect,
#define X(rate) kResponseConnect##rate
		X(600),
		X(1200),
		X(2400),
		X(4800),
		X(7200),
		X(9600),
		X(12000),
		X(14400),
		X(19200),
		X(38400),
		X(57600),
		X(115200),
		X(230400),
#undef X
	};

	const uint32 *begin = kBaudRates;
	const uint32 *end = kBaudRates + sizeof(kBaudRates)/sizeof(kBaudRates[0]);
	const uint32 *it = std::lower_bound(begin, end, rate);

	if (it == end)
		--it;

	if (it != begin && (rate - it[-1]) < (it[0] - rate))
		--it;

	SendResponse(kResponseIds[it - begin]);
}

void ATModemEmulator::SendResponse(int response) {
	if (mRegisters.mbQuietMode || mConfig.mDeviceMode == kATRS232DeviceMode_1030)
		return;

	static const char *const kResponses[]={
		"OK",
		"CONNECT",
		"RING",
		"NO CARRIER",
		"ERROR",
		"CONNECT 1200",
		"NO DIALTONE",
		"BUSY",
		"NO ANSWER",
		"CONNECT 600",
		"CONNECT 2400",
		"CONNECT 4800",
		"CONNECT 9600",
		"CONNECT 7200",
		"CONNECT 12000",
		"CONNECT 14400",
		"CONNECT 19200",
		"CONNECT 38400",
		"CONNECT 57600",
		"CONNECT 115200",
		"CONNECT 230400",
	};

	VDASSERT((unsigned)response < sizeof(kResponses)/sizeof(kResponses[0]));

	if (mRegisters.mbShortResponses) {
		g_ATLCModem("Sending short response: %d (%s)\n", response, kResponses[response]);

		size_t len = response >= 10 ? 3 : 2;

		if (mTransmitLength > sizeof mTransmitBuffer - len)
			return;

		uint8 *dst = mTransmitBuffer + mTransmitLength;

		if (response >= 10) {
			*dst++ = (uint8)('0' + response / 10);
			response %= 10;
		}
		*dst++ = (uint8)('0' + response);
		*dst++ = mRegisters.mLineTermChar;

		mTransmitLength += len;
	} else {
		g_ATLCModem("Sending response: %s\n", kResponses[response]);

		const char *resp = kResponses[response];
		size_t len = strlen(resp);

		if (mTransmitLength > sizeof mTransmitBuffer - (len + 4))
			return;

		uint8 *dst = mTransmitBuffer + mTransmitLength;

		*dst++ = mRegisters.mLineTermChar;
		*dst++ = mRegisters.mRespFormatChar;
		memcpy(dst, resp, len);
		dst += len;
		*dst++ = mRegisters.mLineTermChar;
		*dst++ = mRegisters.mRespFormatChar;

		mTransmitLength += len + 4;
	}
}

void ATModemEmulator::SendResponse(const char *s) {
	size_t len = strlen(s);

	if (sizeof(mTransmitBuffer) - mTransmitLength < len)
		return;

	memcpy(mTransmitBuffer + mTransmitLength, s, len);
	mTransmitLength += len;

	if (mTransmitLength < sizeof mTransmitBuffer)
		mTransmitBuffer[mTransmitLength++] = mRegisters.mLineTermChar;

	if (mTransmitLength < sizeof mTransmitBuffer)
		mTransmitBuffer[mTransmitLength++] = mRegisters.mRespFormatChar;
}

void ATModemEmulator::SendResponseF(const char *format, ...) {
	char buf[512];
	va_list val;

	va_start(val, format);
	int n = _vsnprintf(buf, 512, format, val);
	va_end(val);

	if ((unsigned)n >= 511)
		return;

	SendResponse(buf);
}

void ATModemEmulator::ReportRegisters(const ATModemRegisters& reg, bool stored) {
	SendResponseF("E%u L%u M%u Q%u %c V%u X%u &C%u &D%u &G%u &T%u"
		, reg.mbEchoMode
		, reg.mSpeakerVolume
		, reg.mSpeakerMode
		, reg.mbQuietMode
		, reg.mbToneDialMode ? 'T' : 'P'
		, !reg.mbShortResponses
		, reg.mExtendedResultCodes
		, reg.mbReportCarrier
		, reg.mDTRMode
		, reg.mGuardToneMode
		, reg.mbLoopbackMode
		);

	if (stored) {
		SendResponseF("S00:%03u S02:%03u S06:%03u S07:%03u S10:%03u S12:%03u"
			, reg.mAutoAnswerRings
			, reg.mEscapeChar
			, reg.mDialToneWaitTime
			, reg.mDialCarrierWaitTime
			, reg.mLostCarrierWaitTime
			, reg.mEscapePromptDelay
			);
	} else {
		SendResponseF("S00:%03u S02:%03u S03:%03u S04:%03u S05:%03u S06:%03u S07:%03u"
			, reg.mAutoAnswerRings
			, reg.mEscapeChar
			, reg.mLineTermChar
			, reg.mRespFormatChar
			, reg.mCommandEditChar
			, reg.mDialToneWaitTime
			, reg.mDialCarrierWaitTime
			);

		SendResponseF("S10:%03u S12:%03u"
			, reg.mLostCarrierWaitTime
			, reg.mEscapePromptDelay
			);
	}
}

void ATModemEmulator::TerminateCall() {
	if (mpDriver) {
		mpDriver->Shutdown();
		delete mpDriver;
		mpDriver = NULL;
	}

	mbNewConnectedState = false;
	mConnectionState = kConnectionState_NotConnected;
	mbListening = false;
	mbDeviceTransmitUnderflow = true;
	mDeviceTransmitReadOffset = 0;
	mDeviceTransmitWriteOffset = 0;
	mDeviceTransmitLevel = 0;

	UpdateUIStatus();
	UpdateControlState();
}

void ATModemEmulator::RestoreListeningState() {
	TerminateCall();

	if (!mbListenEnabled)
		return;

	mpDriver = ATCreateModemDriverTCP();
	mpDriver->SetConfig(mConfig);
	if (!mpDriver->Init(NULL, NULL, mConfig.mListenPort, g_ATLCModemTCP.IsEnabled(), this)) {
		TerminateCall();
		return;
	}

	mbListening = true;

	UpdateUIStatus();
}

void ATModemEmulator::UpdateControlState() {
	const bool cd = mRegisters.mbReportCarrier ? mConnectionState == kConnectionState_Connected : true;
	bool changed = false;

	if (mControlState.mbCarrierDetect != cd) {
		mControlState.mbCarrierDetect = cd;
		changed = true;
	}

	mControlState.mbClearToSend = true;
	mControlState.mbDataSetReady = true;

	if (changed && mpCB)
		mpCB->OnControlStateChanged(mControlState);
}

void ATModemEmulator::UpdateUIStatus() {
	if (!mpUIRenderer)
		return;

	VDStringA str;

	switch(mConnectionState) {
		case kConnectionState_NotConnected:
			if (mpDriver) {
				if (mbListening) {
					if (mbRinging) {
						const char *preBracket = "";
						const char *postBracket = "";

						if (mAddress.find(':') != VDStringA::npos) {
							preBracket = "[";
							postBracket = "]";
						}

						str.sprintf("Incoming connection from %s%s%s:%s", preBracket, mAddress.c_str(), postBracket, mService.c_str());
					} else
						str.sprintf("Waiting for connection on port %u", mConfig.mListenPort);
				} else
					str.sprintf("Connecting to %s:%s...", mAddress.c_str(), mService.c_str());
			}
			break;

		case kConnectionState_Connected:
			{
				const char *preBracket = "";
				const char *postBracket = "";

				if (mAddress.find(':') != VDStringA::npos) {
					preBracket = "[";
					postBracket = "]";
				}

				str.sprintf("Connected to %s%s%s:%s%s"
					, preBracket
					, mAddress.c_str()
					, postBracket
					, mService.c_str()
					, mbCommandMode ? " (in command mode)" : "");
			}
			break;

		case kConnectionState_LostCarrier:
			str = "Lost carrier (modem still in online state)";
			break;
	}

	mpUIRenderer->SetModemConnection(str.c_str());
}

void ATModemEmulator::EnterCommandMode(bool sendPrompt, bool force) {
	if (mbCommandMode && !force)
		return;

	if (mpEventEnterCommandMode) {
		mpScheduler->RemoveEvent(mpEventEnterCommandMode);
		mpEventEnterCommandMode = NULL;
	}

	// enter command mode
	if (sendPrompt)
		SendResponse(kResponseOK);

	mGuardCharCounter = 0;
	mbCommandMode = true;
	mCommandLength = 0;
	mCommandState = kCommandState_Idle;

	UpdateUIStatus();
}

int ATModemEmulator::GetRegisterValue(uint32 reg) const {
	switch(reg) {
		case 0:		return mRegisters.mAutoAnswerRings;
		case 2:		return mRegisters.mEscapeChar;
		case 3:		return mRegisters.mLineTermChar;
		case 4:		return mRegisters.mRespFormatChar;
		case 5:		return mRegisters.mCommandEditChar;
		case 6:		return mRegisters.mDialToneWaitTime;
		case 7:		return mRegisters.mDialCarrierWaitTime;
		case 10:	return mRegisters.mLostCarrierWaitTime;
		case 12:	return mRegisters.mEscapePromptDelay;

		default:
			return -1;
	}
}

bool ATModemEmulator::SetRegisterValue(uint32 reg, uint8 value) {
	switch(reg) {
		case 0:
			mRegisters.mAutoAnswerRings = value;
			return true;

		case 2:
			mRegisters.mEscapeChar = value;
			return true;

		case 3:
			mRegisters.mLineTermChar = value;
			return true;

		case 4:
			mRegisters.mRespFormatChar = value;
			return true;

		case 5:
			mRegisters.mCommandEditChar = value;
			return true;

		case 6:
			mRegisters.mDialToneWaitTime = value;
			return true;

		case 7:
			mRegisters.mDialCarrierWaitTime = value;
			return true;

		case 10:
			mRegisters.mLostCarrierWaitTime = value;
			UpdateDerivedRegisters();
			return true;

		case 12:
			mRegisters.mEscapePromptDelay = value;
			return true;

		default:
			return false;
	}
}

void ATModemEmulator::UpdateDerivedRegisters() {
	mLostCarrierDelayCycles = mRegisters.mLostCarrierWaitTime == 255 ? 0 : 715909 * mRegisters.mLostCarrierWaitTime / 4 + 1;
}

void ATModemEmulator::OnScheduledEvent(uint32 id) {
	if (id == 1) {
		mpEventEnterCommandMode = NULL;

		if (mGuardCharCounter >= 3) {
			// enter command mode
			EnterCommandMode(true, true);
		}
	} else if (id == 2) {
		mpEventCommandModeTimeout = NULL;

		if (mbCommandMode && mCommandLength > 0) {
			mCommandLength = 0;

			SendResponse(kResponseError);
		}
	} else if (id == 3) {
		mpEventPoll = mpSlowScheduler->AddEvent(100, this, 3);

		Poll();
	} else if (id == 4) {
		mpEventCommandTermDelay = NULL;
		ParseCommand();
	}
}

void ATModemEmulator::OnReadAvail(IATModemDriver *sender, uint32 len) {
	// do nothing -- we poll this
}

void ATModemEmulator::OnWriteAvail(IATModemDriver *sender) {
	mMutex.Lock();
	for(;;) {
		uint32 tc = mDeviceTransmitLevel;

		if (!tc) {
			mbDeviceTransmitUnderflow = true;
			break;
		}

		if (mDeviceTransmitReadOffset + tc > sizeof mDeviceTransmitBuffer)
			tc = sizeof mDeviceTransmitBuffer - mDeviceTransmitReadOffset;

		tc = sender->Write(mDeviceTransmitBuffer + mDeviceTransmitReadOffset, tc);

		if (!tc)
			break;

		mbDeviceTransmitUnderflow = false;

		mDeviceTransmitReadOffset += tc;
		if (mDeviceTransmitReadOffset >= sizeof mDeviceTransmitBuffer)
			mDeviceTransmitReadOffset = 0;

		mDeviceTransmitLevel -= tc;
	}
	mMutex.Unlock();
}

void ATModemEmulator::OnEvent(IATModemDriver *sender, ATModemPhase phase, ATModemEvent event) {
	if (event == kATModemEvent_Connected)
		mbNewConnectedState = true;
	else {
		if (event == kATModemEvent_ConnectionClosing && !mbRinging)
			return;

		mbNewConnectedState = false;

		if (phase <= kATModemPhase_Connecting)
			mbConnectionFailed = true;
	}
}
