COMMON: Merged the Tinsel & Tony Coroutine schedulers into Common

3 files changed, 1280 insertions, 0 deletions

diff --git a/common/coroutines.cpp b/common/coroutines.cpp
new file mode 100644
index 0000000000..fff6198c22
--- /dev/null
+++ b/common/coroutines.cpp
@@ -0,0 +1,881 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "common/coroutines.h"
+#include "common/textconsole.h"
+#include "common/system.h"
+
+namespace Common {
+
+/** Helper null context instance */
+CoroContext nullContext = NULL;
+
+DECLARE_SINGLETON(CoroutineScheduler);
+
+
+#if COROUTINE_DEBUG
+namespace {
+static int s_coroCount = 0;
+
+typedef Common::HashMap<Common::String, int> CoroHashMap;
+static CoroHashMap *s_coroFuncs = 0;
+
+static void changeCoroStats(const char *func, int change) {
+	if (!s_coroFuncs)
+		s_coroFuncs = new CoroHashMap();
+
+	(*s_coroFuncs)[func] += change;
+}
+
+static void displayCoroStats() {
+	debug("%d active coros", s_coroCount);
+
+	// Loop over s_coroFuncs and print info about active coros
+	if (!s_coroFuncs)
+		return;
+	for (CoroHashMap::const_iterator it = s_coroFuncs->begin();
+		it != s_coroFuncs->end(); ++it) {
+		if (it->_value != 0)
+			debug("  %3d x %s", it->_value, it->_key.c_str());
+	}
+}
+
+}
+#endif
+
+CoroBaseContext::CoroBaseContext(const char *func)
+	: _line(0), _sleep(0), _subctx(0) {
+#if COROUTINE_DEBUG
+	_funcName = func;
+	changeCoroStats(_funcName, +1);
+	s_coroCount++;
+#endif
+}
+
+CoroBaseContext::~CoroBaseContext() {
+#if COROUTINE_DEBUG
+	s_coroCount--;
+	changeCoroStats(_funcName, -1);
+	debug("Deleting coro in %s at %p (subctx %p)",
+		_funcName, (void *)this, (void *)_subctx);
+	displayCoroStats();
+#endif
+	delete _subctx;
+}
+
+//--------------------- Scheduler Class ------------------------
+
+/**
+ * Constructor
+ */
+CoroutineScheduler::CoroutineScheduler() {
+	processList = NULL;
+	pFreeProcesses = NULL;
+	pCurrent = NULL;
+
+#ifdef DEBUG
+	// diagnostic process counters
+	numProcs = 0;
+	maxProcs = 0;
+#endif
+
+	pRCfunction = NULL;
+	pidCounter = 0;
+
+	active = new PROCESS;
+	active->pPrevious = NULL;
+	active->pNext = NULL;
+
+	reset();
+}
+
+/**
+ * Destructor
+ */
+CoroutineScheduler::~CoroutineScheduler() {
+	// Kill all running processes (i.e. free memory allocated for their state).
+	PROCESS *pProc = active->pNext;
+	while (pProc != NULL) {
+		delete pProc->state;
+		pProc->state = 0;
+		pProc = pProc->pNext;
+	}
+
+	free(processList);
+	processList = NULL;
+
+	delete active;
+	active = 0;
+
+	// Clear the event list
+	Common::List<EVENT *>::iterator i;
+	for (i = _events.begin(); i != _events.end(); ++i)
+		delete (*i);
+}
+
+/**
+ * Kills all processes and places them on the free list.
+ */
+void CoroutineScheduler::reset() {
+
+#ifdef DEBUG
+	// clear number of process in use
+	numProcs = 0;
+#endif
+
+	if (processList == NULL) {
+		// first time - allocate memory for process list
+		processList = (PROCESS *)calloc(CORO_MAX_PROCESSES, sizeof(PROCESS));
+
+		// make sure memory allocated
+		if (processList == NULL) {
+			error("Cannot allocate memory for process data");
+		}
+
+		// fill with garbage
+		memset(processList, 'S', CORO_MAX_PROCESSES * sizeof(PROCESS));
+	}
+
+	// Kill all running processes (i.e. free memory allocated for their state).
+	PROCESS *pProc = active->pNext;
+	while (pProc != NULL) {
+		delete pProc->state;
+		pProc->state = 0;
+		pProc->waiting = false;
+		pProc = pProc->pNext;
+	}
+
+	// no active processes
+	pCurrent = active->pNext = NULL;
+
+	// place first process on free list
+	pFreeProcesses = processList;
+
+	// link all other processes after first
+	for (int i = 1; i <= CORO_NUM_PROCESS; i++) {
+		processList[i - 1].pNext = (i == CORO_NUM_PROCESS) ? NULL : processList + i;
+		processList[i - 1].pPrevious = (i == 1) ? active : processList + (i - 2);
+	}
+}
+
+
+#ifdef	DEBUG
+/**
+ * Shows the maximum number of process used at once.
+ */
+void CoroutineScheduler::printStats() {
+	debug("%i process of %i used", maxProcs, CORO_NUM_PROCESS);
+}
+#endif
+
+#ifdef DEBUG
+/**
+ * Checks both the active and free process list to insure all the links are valid,
+ * and that no processes have been lost
+ */
+void CoroutineScheduler::CheckStack() {
+	Common::List<PROCESS *> pList;
+
+	// Check both the active and free process lists
+	for (int i = 0; i < 2; ++i) {
+		PROCESS *p = (i == 0) ? active : pFreeProcesses;
+
+		if (p != NULL) {
+			// Make sure the linkages are correct
+			while (p->pNext != NULL) {
+				assert(p->pNext->pPrevious == p);
+				pList.push_back(p);
+				p = p->pNext;
+			}
+			pList.push_back(p);
+		}
+	}
+
+	// Make sure all processes are accounted for
+	for (int idx = 0; idx < CORO_NUM_PROCESS; idx++) {
+		bool found = false;
+		for (Common::List<PROCESS *>::iterator i = pList.begin(); i != pList.end(); ++i) {
+			PROCESS *pTemp = *i;
+			if (*i == &processList[idx]) {
+				found = true;
+				break;
+			}
+		}
+
+		assert(found);
+	}
+}
+#endif
+
+/**
+ * Give all active processes a chance to run
+ */
+void CoroutineScheduler::schedule() {
+	// start dispatching active process list
+	PROCESS *pNext;
+	PROCESS *pProc = active->pNext;
+	while (pProc != NULL) {
+		pNext = pProc->pNext;
+
+		if (--pProc->sleepTime <= 0) {
+			// process is ready for dispatch, activate it
+			pCurrent = pProc;
+			pProc->coroAddr(pProc->state, pProc->param);
+
+			if (!pProc->state || pProc->state->_sleep <= 0) {
+				// Coroutine finished
+				pCurrent = pCurrent->pPrevious;
+				killProcess(pProc);
+			} else {
+				pProc->sleepTime = pProc->state->_sleep;
+			}
+
+			// pCurrent may have been changed
+			pNext = pCurrent->pNext;
+			pCurrent = NULL;
+		}
+
+		pProc = pNext;
+	}
+}
+
+/**
+ * Reschedules all the processes to run again this query
+ */
+void CoroutineScheduler::rescheduleAll() {
+	assert(pCurrent);
+
+	// Unlink current process
+	pCurrent->pPrevious->pNext = pCurrent->pNext;
+	if (pCurrent->pNext)
+		pCurrent->pNext->pPrevious = pCurrent->pPrevious;
+
+	// Add process to the start of the active list
+	pCurrent->pNext = active->pNext;
+	active->pNext->pPrevious = pCurrent;
+	active->pNext = pCurrent;
+	pCurrent->pPrevious = active;
+}
+
+/**
+ * If the specified process has already run on this tick, make it run
+ * again on the current tick.
+ */
+void CoroutineScheduler::reschedule(PPROCESS pReSchedProc) {
+	// If not currently processing the schedule list, then no action is needed
+	if (!pCurrent)
+		return;
+
+	if (!pReSchedProc)
+		pReSchedProc = pCurrent;
+
+	PPROCESS pEnd;
+
+	// Find the last process in the list.
+	// But if the target process is down the list from here, do nothing
+	for (pEnd = pCurrent; pEnd->pNext != NULL; pEnd = pEnd->pNext) {
+		if (pEnd->pNext == pReSchedProc)
+			return;
+	}
+
+	assert(pEnd->pNext == NULL);
+
+	// Could be in the middle of a KillProc()!
+	// Dying process was last and this process was penultimate
+	if (pReSchedProc->pNext == NULL)
+		return;
+
+	// If we're moving the current process, move it back by one, so that the next
+	// schedule() iteration moves to the now next one
+	if (pCurrent == pReSchedProc)
+		pCurrent = pCurrent->pPrevious;
+
+	// Unlink the process, and add it at the end
+	pReSchedProc->pPrevious->pNext = pReSchedProc->pNext;
+	pReSchedProc->pNext->pPrevious = pReSchedProc->pPrevious;
+	pEnd->pNext = pReSchedProc;
+	pReSchedProc->pPrevious = pEnd;
+	pReSchedProc->pNext = NULL;
+}
+
+/**
+ * Moves the specified process to the end of the dispatch queue
+ * allowing it to run again within the current game cycle.
+ * @param pGiveProc		Which process
+ */
+void CoroutineScheduler::giveWay(PPROCESS pReSchedProc) {
+	// If not currently processing the schedule list, then no action is needed
+	if (!pCurrent)
+		return;
+
+	if (!pReSchedProc)
+		pReSchedProc = pCurrent;
+
+	// If the process is already at the end of the queue, nothing has to be done
+	if (!pReSchedProc->pNext)
+		return;
+
+	PPROCESS pEnd;
+
+	// Find the last process in the list.
+	for (pEnd = pCurrent; pEnd->pNext != NULL; pEnd = pEnd->pNext)
+		;
+	assert(pEnd->pNext == NULL);
+
+
+	// If we're moving the current process, move it back by one, so that the next
+	// schedule() iteration moves to the now next one
+	if (pCurrent == pReSchedProc)
+		pCurrent = pCurrent->pPrevious;
+
+	// Unlink the process, and add it at the end
+	pReSchedProc->pPrevious->pNext = pReSchedProc->pNext;
+	pReSchedProc->pNext->pPrevious = pReSchedProc->pPrevious;
+	pEnd->pNext = pReSchedProc;
+	pReSchedProc->pPrevious = pEnd;
+	pReSchedProc->pNext = NULL;
+}
+
+/**
+ * Continously makes a given process wait for another process to finish or event to signal.
+ *
+ * @param pid			Process/Event identifier
+ * @param duration		Duration in milliseconds
+ * @param expired		If specified, set to true if delay period expired
+ */
+void CoroutineScheduler::waitForSingleObject(CORO_PARAM, int pid, uint32 duration, bool *expired) {
+	if (!pCurrent)
+		error("Called CoroutineScheduler::waitForSingleObject from the main process");
+
+	CORO_BEGIN_CONTEXT;
+		uint32 endTime;
+		PROCESS *pProcess;
+		EVENT *pEvent;
+	CORO_END_CONTEXT(_ctx);
+
+	CORO_BEGIN_CODE(_ctx);
+
+	// Signal as waiting
+	pCurrent->waiting = true;
+
+	_ctx->endTime = (duration == CORO_INFINITE) ? CORO_INFINITE : g_system->getMillis() + duration;
+	if (expired)
+		// Presume it will expire
+		*expired = true;
+
+	// Outer loop for doing checks until expiry 
+	while (g_system->getMillis() < _ctx->endTime) {
+		// Check to see if a process or event with the given Id exists
+		_ctx->pProcess = getProcess(pid);
+		_ctx->pEvent = !_ctx->pProcess ? getEvent(pid) : NULL;
+
+		// If there's no active process or event, presume it's a process that's finished,
+		// so the waiting can immediately exit
+		if ((_ctx->pProcess == NULL) && (_ctx->pEvent == NULL)) {
+			if (expired)
+				*expired = false;
+			break;
+		}
+
+		// If a process was found, don't go into the if statement, and keep waiting. 
+		// Likewise if it's an event that's not yet signalled
+		if ((_ctx->pEvent != NULL) && _ctx->pEvent->signalled) {
+			// Unless the event is flagged for manual reset, reset it now
+			if (!_ctx->pEvent->manualReset)
+				_ctx->pEvent->signalled = false;
+
+			if (expired)
+				*expired = false;
+			break;
+		}
+
+		// Sleep until the next cycle
+		CORO_SLEEP(1);
+	}
+
+	// Signal waiting is done
+	pCurrent->waiting = false;
+
+	CORO_END_CODE;
+}
+
+/**
+ * Continously makes a given process wait for given prcesses to finished or events to be set
+ *
+ * @param nCount		Number of Id's being passed
+ * @param evtList		List of pids to wait for
+ * @param bWaitAll		Specifies whether all or any of the processes/events 
+ * @param duration		Duration in milliseconds
+ * @param expired		Set to true if delay period expired
+ */
+void CoroutineScheduler::waitForMultipleObjects(CORO_PARAM, int nCount, uint32 *pidList, bool bWaitAll, 
+						   uint32 duration, bool *expired) {
+	if (!pCurrent)
+		error("Called CoroutineScheduler::waitForMultipleEvents from the main process");
+
+	CORO_BEGIN_CONTEXT;
+		uint32 endTime;
+		bool signalled;
+		bool pidSignalled;
+		int i;
+		PROCESS *pProcess;
+		EVENT *pEvent;
+	CORO_END_CONTEXT(_ctx);
+
+	CORO_BEGIN_CODE(_ctx);
+
+	// Signal as waiting
+	pCurrent->waiting = true;
+
+	_ctx->endTime = (duration == CORO_INFINITE) ? CORO_INFINITE : g_system->getMillis() + duration;
+	if (expired)
+		// Presume that delay will expire
+		*expired = true;
+
+	// Outer loop for doing checks until expiry 
+	while (g_system->getMillis() < _ctx->endTime) {
+		_ctx->signalled = bWaitAll;
+
+		for (_ctx->i = 0; _ctx->i < nCount; ++_ctx->i) {
+			_ctx->pProcess = getProcess(pidList[_ctx->i]);
+			_ctx->pEvent = !_ctx->pProcess ? getEvent(pidList[_ctx->i]) : NULL;
+
+			// Determine the signalled state
+			_ctx->pidSignalled = (_ctx->pProcess) || !_ctx->pEvent ? false : _ctx->pEvent->signalled;
+
+			if (bWaitAll && _ctx->pidSignalled)
+				_ctx->signalled = false;
+			else if (!bWaitAll & _ctx->pidSignalled)
+				_ctx->signalled = true;
+		}
+
+		// At this point, if the signalled variable is set, waiting is finished
+		if (_ctx->signalled) {
+			// Automatically reset any events not flagged for manual reset
+			for (_ctx->i = 0; _ctx->i < nCount; ++_ctx->i) {
+				_ctx->pEvent = getEvent(pidList[_ctx->i]);
+
+				if (_ctx->pEvent->manualReset)
+					_ctx->pEvent->signalled = false;
+			}
+
+			if (expired)
+				*expired = false;
+			break;
+		}
+
+		// Sleep until the next cycle
+		CORO_SLEEP(1);
+	}
+
+	// Signal waiting is done
+	pCurrent->waiting = false;
+
+	CORO_END_CODE;
+}
+
+/**
+ * Make the active process sleep for the given duration in milliseconds
+ * @param duration					Duration in milliseconds
+ * @remarks		This duration won't be precise, since it relies on the frequency the
+ * scheduler is called.
+ */
+void CoroutineScheduler::sleep(CORO_PARAM, uint32 duration) {
+	if (!pCurrent)
+		error("Called CoroutineScheduler::waitForSingleObject from the main process");
+
+	CORO_BEGIN_CONTEXT;
+		uint32 endTime;
+		PROCESS *pProcess;
+		EVENT *pEvent;
+	CORO_END_CONTEXT(_ctx);
+
+	CORO_BEGIN_CODE(_ctx);
+
+	// Signal as waiting
+	pCurrent->waiting = true;
+
+	_ctx->endTime = g_system->getMillis() + duration;
+
+	// Outer loop for doing checks until expiry 
+	while (g_system->getMillis() < _ctx->endTime) {
+		// Sleep until the next cycle
+		CORO_SLEEP(1);
+	}
+
+	// Signal waiting is done
+	pCurrent->waiting = false;
+
+	CORO_END_CODE;
+}
+
+/**
+ * Creates a new process.
+ *
+ * @param pid	process identifier
+ * @param CORO_ADDR	coroutine start address
+ * @param pParam	process specific info
+ * @param sizeParam	size of process specific info
+ */
+PROCESS *CoroutineScheduler::createProcess(uint32 pid, CORO_ADDR coroAddr, const void *pParam, int sizeParam) {
+	PROCESS *pProc;
+
+	// get a free process
+	pProc = pFreeProcesses;
+
+	// trap no free process
+	assert(pProc != NULL); // Out of processes
+
+#ifdef DEBUG
+	// one more process in use
+	if (++numProcs > maxProcs)
+		maxProcs = numProcs;
+#endif
+
+	// get link to next free process
+	pFreeProcesses = pProc->pNext;
+	if (pFreeProcesses)
+		pFreeProcesses->pPrevious = NULL;
+
+	if (pCurrent != NULL) {
+		// place new process before the next active process
+		pProc->pNext = pCurrent->pNext;
+		if (pProc->pNext)
+			pProc->pNext->pPrevious = pProc;
+
+		// make this new process the next active process
+		pCurrent->pNext = pProc;
+		pProc->pPrevious = pCurrent;
+
+	} else {	// no active processes, place process at head of list
+		pProc->pNext = active->pNext;
+		pProc->pPrevious = active;
+
+		if (pProc->pNext)
+			pProc->pNext->pPrevious = pProc;
+		active->pNext = pProc;
+
+	}
+
+	// set coroutine entry point
+	pProc->coroAddr = coroAddr;
+
+	// clear coroutine state
+	pProc->state = 0;
+
+	// wake process up as soon as possible
+	pProc->sleepTime = 1;
+
+	// set new process id
+	pProc->pid = pid;
+
+	// set new process specific info
+	if (sizeParam) {
+		assert(sizeParam > 0 && sizeParam <= CORO_PARAM_SIZE);
+
+		// set new process specific info
+		memcpy(pProc->param, pParam, sizeParam);
+	}
+
+	// return created process
+	return pProc;
+}
+
+/**
+ * Creates a new process with an auto-incrementing Process Id.
+ *
+ * @param CORO_ADDR	coroutine start address
+ * @param pParam	process specific info
+ * @param sizeParam	size of process specific info
+ */
+uint32 CoroutineScheduler::createProcess(CORO_ADDR coroAddr, const void *pParam, int sizeParam) {
+	PROCESS *pProc = createProcess(++pidCounter, coroAddr, pParam, sizeParam);
+	return pProc->pid;
+}
+
+/**
+ * Creates a new process with an auto-incrementing Process Id, and a single pointer parameter.
+ *
+ * @param CORO_ADDR	coroutine start address
+ * @param pParam	process specific info
+ * @param sizeParam	size of process specific info
+ */
+uint32 CoroutineScheduler::createProcess(CORO_ADDR coroAddr, const void *pParam) {
+	return createProcess(coroAddr, &pParam, sizeof(void *));
+}
+
+
+/**
+ * Kills the specified process.
+ *
+ * @param pKillProc	which process to kill
+ */
+void CoroutineScheduler::killProcess(PROCESS *pKillProc) {
+	// make sure a valid process pointer
+	assert(pKillProc >= processList && pKillProc <= processList + CORO_NUM_PROCESS - 1);
+
+	// can not kill the current process using killProcess !
+	assert(pCurrent != pKillProc);
+
+#ifdef DEBUG
+	// one less process in use
+	--numProcs;
+	assert(numProcs >= 0);
+#endif
+
+	// Free process' resources
+	if (pRCfunction != NULL)
+		(pRCfunction)(pKillProc);
+
+	delete pKillProc->state;
+	pKillProc->state = 0;
+
+	// Take the process out of the active chain list
+	pKillProc->pPrevious->pNext = pKillProc->pNext;
+	if (pKillProc->pNext)
+		pKillProc->pNext->pPrevious = pKillProc->pPrevious;
+
+	// link first free process after pProc
+	pKillProc->pNext = pFreeProcesses;
+	if (pFreeProcesses)
+		pKillProc->pNext->pPrevious = pKillProc;
+	pKillProc->pPrevious = NULL;
+
+	// make pKillProc the first free process
+	pFreeProcesses = pKillProc;
+}
+
+
+
+/**
+ * Returns a pointer to the currently running process.
+ */
+PROCESS *CoroutineScheduler::getCurrentProcess() {
+	return pCurrent;
+}
+
+/**
+ * Returns the process identifier of the specified process.
+ *
+ * @param pProc	which process
+ */
+int CoroutineScheduler::getCurrentPID() const {
+	PROCESS *pProc = pCurrent;
+
+	// make sure a valid process pointer
+	assert(pProc >= processList && pProc <= processList + CORO_NUM_PROCESS - 1);
+
+	// return processes PID
+	return pProc->pid;
+}
+
+/**
+ * Kills any process matching the specified PID. The current
+ * process cannot be killed.
+ *
+ * @param pidKill	process identifier of process to kill
+ * @param pidMask	mask to apply to process identifiers before comparison
+ * @return The number of processes killed is returned.
+ */
+int CoroutineScheduler::killMatchingProcess(uint32 pidKill, int pidMask) {
+	int numKilled = 0;
+	PROCESS *pProc, *pPrev;	// process list pointers
+
+	for (pProc = active->pNext, pPrev = active; pProc != NULL; pPrev = pProc, pProc = pProc->pNext) {
+		if ((pProc->pid & (uint32)pidMask) == pidKill) {
+			// found a matching process
+
+			// dont kill the current process
+			if (pProc != pCurrent) {
+				// kill this process
+				numKilled++;
+
+				// Free the process' resources
+				if (pRCfunction != NULL)
+					(pRCfunction)(pProc);
+
+				delete pProc->state;
+				pProc->state = 0;
+
+				// make prev point to next to unlink pProc
+				pPrev->pNext = pProc->pNext;
+				if (pProc->pNext)
+					pPrev->pNext->pPrevious = pPrev;
+
+				// link first free process after pProc
+				pProc->pNext = pFreeProcesses;
+				pProc->pPrevious = NULL;
+				pFreeProcesses->pPrevious = pProc;
+
+				// make pProc the first free process
+				pFreeProcesses = pProc;
+
+				// set to a process on the active list
+				pProc = pPrev;
+			}
+		}
+	}
+
+#ifdef DEBUG
+	// adjust process in use
+	numProcs -= numKilled;
+	assert(numProcs >= 0);
+#endif
+
+	// return number of processes killed
+	return numKilled;
+}
+
+/**
+ * Set pointer to a function to be called by killProcess().
+ *
+ * May be called by a resource allocator, the function supplied is
+ * called by killProcess() to allow the resource allocator to free
+ * resources allocated to the dying process.
+ *
+ * @param pFunc	Function to be called by killProcess()
+ */
+void CoroutineScheduler::setResourceCallback(VFPTRPP pFunc) {
+	pRCfunction = pFunc;
+}
+
+PROCESS *CoroutineScheduler::getProcess(uint32 pid) {
+	PROCESS *pProc = active->pNext;
+	while ((pProc != NULL) && (pProc->pid != pid))
+		pProc = pProc->pNext;
+
+	return pProc;
+}
+
+EVENT *CoroutineScheduler::getEvent(uint32 pid) {
+	Common::List<EVENT *>::iterator i;
+	for (i = _events.begin(); i != _events.end(); ++i) {
+		EVENT *evt = *i;
+		if (evt->pid == pid)
+			return evt;
+	}
+
+	return NULL;
+}
+
+
+/**
+ * Creates a new event object
+ * @param bManualReset					Events needs to be manually reset. Otherwise, events
+ * will be automatically reset after a process waits on the event finishes
+ * @param bInitialState					Specifies whether the event is signalled or not initially
+ */
+uint32 CoroutineScheduler::createEvent(bool bManualReset, bool bInitialState) {
+	EVENT *evt = new EVENT();
+	evt->pid = ++pidCounter;
+	evt->manualReset = bManualReset;
+	evt->signalled = bInitialState;
+
+	_events.push_back(evt);
+	return evt->pid;
+}
+
+/**
+ * Destroys the given event
+ * @param pidEvent						Event PID
+ */
+void CoroutineScheduler::closeEvent(uint32 pidEvent) {
+	EVENT *evt = getEvent(pidEvent);
+	if (evt) {
+		_events.remove(evt);
+		delete evt;
+	}
+}
+
+/**
+ * Sets the event
+ * @param pidEvent						Event PID
+ */
+void CoroutineScheduler::setEvent(uint32 pidEvent) {
+	EVENT *evt = getEvent(pidEvent);
+	if (evt)
+		evt->signalled = true;
+}
+
+/**
+ * Resets the event
+ * @param pidEvent						Event PID
+ */
+void CoroutineScheduler::resetEvent(uint32 pidEvent) {
+	EVENT *evt = getEvent(pidEvent);
+	if (evt)
+		evt->signalled = false;
+}
+
+/**
+ * Temporarily sets a given event to true, and then runs all waiting processes, allowing any
+ * processes waiting on the event to be fired. It then immediately resets the event again.
+ * @param pidEvent						Event PID
+ *
+ * @remarks		Should not be run inside of another process
+ */
+void CoroutineScheduler::pulseEvent(uint32 pidEvent) {
+	EVENT *evt = getEvent(pidEvent);
+	if (!evt)
+		return;
+	
+	// Set the event as true
+	evt->signalled = true;
+	
+	// start dispatching active process list for any processes that are currently waiting
+	PROCESS *pOriginal = pCurrent;
+	PROCESS *pNext;
+	PROCESS *pProc = active->pNext;
+	while (pProc != NULL) {
+		pNext = pProc->pNext;
+
+		// Only call processes that are currently waiting (either in waitForSingleObject or
+		// waitForMultipleObjects). If one is found, execute it immediately
+		if (pProc->waiting) {
+			// Dispatch the process
+			pCurrent = pProc;
+			pProc->coroAddr(pProc->state, pProc->param);
+
+			if (!pProc->state || pProc->state->_sleep <= 0) {
+				// Coroutine finished
+				pCurrent = pCurrent->pPrevious;
+				killProcess(pProc);
+			} else {
+				pProc->sleepTime = pProc->state->_sleep;
+			}
+
+			// pCurrent may have been changed
+			pNext = pCurrent->pNext;
+			pCurrent = NULL;
+		}
+
+		pProc = pNext;
+	}
+
+	// Restore the original current process (if one was active)
+	pCurrent = pOriginal;
+
+	// Reset the event back to non-signalled
+	evt->signalled = false;
+}
+
+
+} // end of namespace Common
diff --git a/common/coroutines.h b/common/coroutines.h
new file mode 100644
index 0000000000..3303028e1c
--- /dev/null
+++ b/common/coroutines.h
@@ -0,0 +1,398 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#ifndef COMMON_COROUTINES_H
+#define COMMON_COROUTINES_H
+
+#include "common/scummsys.h"
+#include "common/util.h"	// for SCUMMVM_CURRENT_FUNCTION
+#include "common/list.h"
+#include "common/singleton.h"
+
+namespace Common {
+
+/**
+ * @defgroup Coroutine support for simulating multi-threading.
+ *
+ * The following is loosely based on an article by Simon Tatham:
+ *   <http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html>.
+ * However, many improvements and tweaks have been made, in particular
+ * by taking advantage of C++ features not available in C.
+ */
+//@{
+
+#define CoroScheduler (Common::CoroutineScheduler::instance())
+
+
+// Enable this macro to enable some debugging support in the coroutine code.
+//#define COROUTINE_DEBUG	1
+
+/**
+ * The core of any coroutine context which captures the 'state' of a coroutine.
+ * Private use only.
+ */
+struct CoroBaseContext {
+	int _line;
+	int _sleep;
+	CoroBaseContext *_subctx;
+#if COROUTINE_DEBUG
+	const char *_funcName;
+#endif
+	CoroBaseContext(const char *func);
+	~CoroBaseContext();
+};
+
+typedef CoroBaseContext *CoroContext;
+
+
+/** This is a special constant that can be temporarily used as a parameter to call coroutine-ised
+ * from methods from methods that haven't yet been converted to being a coroutine, so code at least
+ * compiles correctly. Be aware, though, that if you use this, you will get runtime errors.
+ */
+extern CoroContext nullContext;
+
+/**
+ * Wrapper class which holds a pointer to a pointer to a CoroBaseContext.
+ * The interesting part is the destructor, which kills the context being held,
+ * but ONLY if the _sleep val of that context is zero. This way, a coroutine
+ * can just 'return' w/o having to worry about freeing the allocated context
+ * (in Simon Tatham's original code, one had to use a special macro to
+ * return from a coroutine).
+ */
+class CoroContextHolder {
+	CoroContext &_ctx;
+public:
+	CoroContextHolder(CoroContext &ctx) : _ctx(ctx) {
+		assert(ctx);
+		assert(ctx->_sleep >= 0);
+		ctx->_sleep = 0;
+	}
+	~CoroContextHolder() {
+		if (_ctx && _ctx->_sleep == 0) {
+			delete _ctx;
+			_ctx = 0;
+		}
+	}
+};
+
+/** Methods that have been converted to being a coroutine should have this as the first parameter */
+#define CORO_PARAM    Common::CoroContext &coroParam
+
+
+/**
+ * Begin the declaration of a coroutine context.
+ * This allows declaring variables which are 'persistent' during the
+ * lifetime of the coroutine. An example use would be:
+ *
+ *  CORO_BEGIN_CONTEXT;
+ *    int var;
+ *    char *foo;
+ *  CORO_END_CONTEXT(_ctx);
+ *
+ * It is not possible to initialize variables here, due to the way this
+ * macro is implemented. Furthermore, to use the variables declared in
+ * the coroutine context, you have to access them via the context variable
+ * name that was specified as parameter to CORO_END_CONTEXT, e.g.
+ *   _ctx->var = 0;
+ *
+ * @see CORO_END_CONTEXT
+ *
+ * @note We declare a variable 'DUMMY' to allow the user to specify an 'empty'
+ * context, and so compilers won't complain about ";" following the macro.
+ */
+#define CORO_BEGIN_CONTEXT  \
+	struct CoroContextTag : Common::CoroBaseContext { \
+		CoroContextTag() : CoroBaseContext(SCUMMVM_CURRENT_FUNCTION) {} \
+		int DUMMY
+
+/**
+ * End the declaration of a coroutine context.
+ * @param x	name of the coroutine context
+ * @see CORO_BEGIN_CONTEXT
+ */
+#define CORO_END_CONTEXT(x)    } *x = (CoroContextTag *)coroParam
+
+/**
+ * Begin the code section of a coroutine.
+ * @param x	name of the coroutine context
+ * @see CORO_BEGIN_CODE
+ */
+#define CORO_BEGIN_CODE(x) \
+		if (&coroParam == &Common::nullContext) assert(!Common::nullContext);\
+		if (!x) {coroParam = x = new CoroContextTag();}\
+		Common::CoroContextHolder tmpHolder(coroParam);\
+		switch (coroParam->_line) { case 0:;
+
+/**
+ * End the code section of a coroutine.
+ * @see CORO_END_CODE
+ */
+#define CORO_END_CODE \
+			if (&coroParam == &Common::nullContext) { \
+				delete Common::nullContext; \
+				Common::nullContext = NULL; \
+			} \
+		}
+
+/**
+ * Sleep for the specified number of scheduler cycles.
+ */
+#define CORO_SLEEP(delay) do {\
+			coroParam->_line = __LINE__;\
+			coroParam->_sleep = delay;\
+			assert(&coroParam != &Common::nullContext);\
+			return; case __LINE__:;\
+		} while (0)
+
+#define CORO_GIVE_WAY do { CoroScheduler.giveWay(); CORO_SLEEP(1); } while (0)
+#define CORO_RESCHEDULE do { CoroScheduler.reschedule(); CORO_SLEEP(1); } while (0)
+
+/**
+ * Stop the currently running coroutine and all calling coroutines.
+ *
+ * This sets _sleep to -1 rather than 0 so that the context doesn't get
+ * deleted by CoroContextHolder, since we want CORO_INVOKE_ARGS to
+ * propogate the _sleep value and return immediately (the scheduler will
+ * then delete the entire coroutine's state, including all subcontexts).
+ */
+#define CORO_KILL_SELF() \
+		do { if (&coroParam != &Common::nullContext) { coroParam->_sleep = -1; } return; } while (0)
+
+
+/**
+ * This macro is to be used in conjunction with CORO_INVOKE_ARGS and
+ * similar macros for calling coroutines-enabled subroutines.
+ */
+#define CORO_SUBCTX   coroParam->_subctx
+
+/**
+ * Invoke another coroutine.
+ *
+ * If the subcontext still exists after the coroutine is invoked, it has
+ * either yielded/slept or killed itself, and so we copy the _sleep value
+ * to our own context and return (execution will continue at the case
+ * statement below, where we loop and call the coroutine again).
+ * If the subcontext is null, the coroutine ended normally, and we can
+ * simply break out of the loop and continue execution.
+ *
+ * @param subCoro	name of the coroutine-enabled function to invoke
+ * @param ARGS		list of arguments to pass to subCoro
+ *
+ * @note ARGS must be surrounded by parentheses, and the first argument
+ *       in this list must always be CORO_SUBCTX. For example, the
+ *       regular function call
+ *          myFunc(a, b);
+ *       becomes the following:
+ *          CORO_INVOKE_ARGS(myFunc, (CORO_SUBCTX, a, b));
+ */
+#define CORO_INVOKE_ARGS(subCoro, ARGS)  \
+		do {\
+			coroParam->_line = __LINE__;\
+			coroParam->_subctx = 0;\
+			do {\
+				subCoro ARGS;\
+				if (!coroParam->_subctx) break;\
+				coroParam->_sleep = coroParam->_subctx->_sleep;\
+				assert(&coroParam != &Common::nullContext);\
+				return; case __LINE__:;\
+			} while (1);\
+		} while (0)
+
+/**
+ * Invoke another coroutine. Similar to CORO_INVOKE_ARGS,
+ * but allows specifying a return value which is returned
+ * if invoked coroutine yields (thus causing the current
+ * coroutine to yield, too).
+ */
+#define CORO_INVOKE_ARGS_V(subCoro, RESULT, ARGS)  \
+		do {\
+			coroParam->_line = __LINE__;\
+			coroParam->_subctx = 0;\
+			do {\
+				subCoro ARGS;\
+				if (!coroParam->_subctx) break;\
+				coroParam->_sleep = coroParam->_subctx->_sleep;\
+				assert(&coroParam != &Common::nullContext);\
+				return RESULT; case __LINE__:;\
+			} while (1);\
+		} while (0)
+
+/**
+ * Convenience wrapper for CORO_INVOKE_ARGS for invoking a coroutine
+ * with no parameters.
+ */
+#define CORO_INVOKE_0(subCoroutine) \
+			CORO_INVOKE_ARGS(subCoroutine,(CORO_SUBCTX))
+
+/**
+ * Convenience wrapper for CORO_INVOKE_ARGS for invoking a coroutine
+ * with one parameter.
+ */
+#define CORO_INVOKE_1(subCoroutine, a0) \
+			CORO_INVOKE_ARGS(subCoroutine,(CORO_SUBCTX,a0))
+
+/**
+ * Convenience wrapper for CORO_INVOKE_ARGS for invoking a coroutine
+ * with two parameters.
+ */
+#define CORO_INVOKE_2(subCoroutine, a0,a1) \
+			CORO_INVOKE_ARGS(subCoroutine,(CORO_SUBCTX,a0,a1))
+
+/**
+ * Convenience wrapper for CORO_INVOKE_ARGS for invoking a coroutine
+ * with three parameters.
+ */
+#define CORO_INVOKE_3(subCoroutine, a0,a1,a2) \
+			CORO_INVOKE_ARGS(subCoroutine,(CORO_SUBCTX,a0,a1,a2))
+
+/**
+ * Convenience wrapper for CORO_INVOKE_ARGS for invoking a coroutine
+ * with four parameters.
+ */
+#define CORO_INVOKE_4(subCoroutine, a0,a1,a2,a3) \
+			CORO_INVOKE_ARGS(subCoroutine,(CORO_SUBCTX,a0,a1,a2,a3))
+
+
+
+// the size of process specific info
+#define	CORO_PARAM_SIZE	32
+
+// the maximum number of processes
+#define	CORO_NUM_PROCESS	100
+#define CORO_MAX_PROCESSES	100
+
+#define CORO_INFINITE 0xffffffff
+#define CORO_INVALID_PID_VALUE 0
+
+typedef void (*CORO_ADDR)(CoroContext &, const void *);
+
+/** process structure */
+struct PROCESS {
+	PROCESS *pNext;		///< pointer to next process in active or free list
+	PROCESS *pPrevious;	///< pointer to previous process in active or free list
+
+	CoroContext state;		///< the state of the coroutine
+	CORO_ADDR  coroAddr;	///< the entry point of the coroutine
+
+	int sleepTime;		///< number of scheduler cycles to sleep
+	uint32 pid;			///< process ID
+	bool waiting;		///< process is currently in a waiting state
+	char param[CORO_PARAM_SIZE];	///< process specific info
+};
+typedef PROCESS *PPROCESS;
+
+
+/** Event structure */
+struct EVENT {
+	uint32 pid;
+	bool manualReset;
+	bool signalled;
+};
+
+
+/**
+ * Creates and manages "processes" (really coroutines).
+ */
+class CoroutineScheduler: public Singleton<CoroutineScheduler> {
+public:
+	/** Pointer to a function of the form "void function(PPROCESS)" */
+	typedef void (*VFPTRPP)(PROCESS *);
+
+private:
+
+	/** list of all processes */
+	PROCESS *processList;
+
+	/** active process list - also saves scheduler state */
+	PROCESS *active;
+
+	/** pointer to free process list */
+	PROCESS *pFreeProcesses;
+
+	/** the currently active process */
+	PROCESS *pCurrent;
+
+	/** Auto-incrementing process Id */
+	int pidCounter;
+
+	/** Event list */
+	Common::List<EVENT *> _events;
+
+#ifdef DEBUG
+	// diagnostic process counters
+	int numProcs;
+	int maxProcs;
+
+	void CheckStack();
+#endif
+
+	/**
+	 * Called from killProcess() to enable other resources
+	 * a process may be allocated to be released.
+	 */
+	VFPTRPP pRCfunction;
+
+	PROCESS *getProcess(uint32 pid);
+	EVENT *getEvent(uint32 pid);
+public:
+
+	CoroutineScheduler();
+	~CoroutineScheduler();
+
+	void reset();
+
+	#ifdef	DEBUG
+	void printStats();
+	#endif
+
+	void schedule();
+	void rescheduleAll();
+	void reschedule(PPROCESS pReSchedProc = NULL);
+	void giveWay(PPROCESS pReSchedProc = NULL);
+	void waitForSingleObject(CORO_PARAM, int pid, uint32 duration, bool *expired = NULL);
+	void waitForMultipleObjects(CORO_PARAM, int nCount, uint32 *pidList, bool bWaitAll, 
+			uint32 duration, bool *expired = NULL);
+	void sleep(CORO_PARAM, uint32 duration);
+
+	PROCESS *createProcess(uint32 pid, CORO_ADDR coroAddr, const void *pParam, int sizeParam);
+	uint32 createProcess(CORO_ADDR coroAddr, const void *pParam, int sizeParam);
+	uint32 createProcess(CORO_ADDR coroAddr, const void *pParam);
+	void killProcess(PROCESS *pKillProc);
+
+	PROCESS *getCurrentProcess();
+	int getCurrentPID() const;
+	int killMatchingProcess(uint32 pidKill, int pidMask = -1);
+
+	void setResourceCallback(VFPTRPP pFunc);
+
+	/* Event methods */
+	uint32 createEvent(bool bManualReset, bool bInitialState);
+	void closeEvent(uint32 pidEvent);
+	void setEvent(uint32 pidEvent);
+	void resetEvent(uint32 pidEvent);
+	void pulseEvent(uint32 pidEvent);
+};
+
+//@}
+
+} // end of namespace Common
+
+#endif		// COMMON_COROUTINES_H
diff --git a/common/module.mk b/common/module.mk
index 7e31ddfa01..92279740e5 100644
--- a/common/module.mk
+++ b/common/module.mk
@@ -4,6 +4,7 @@ MODULE_OBJS := \
 	archive.o \
 	config-file.o \
 	config-manager.o \
+	coroutines.o \
 	dcl.o \
 	debug.o \
 	error.o \