I hate timers

include/kernel/kernel.hpp

@@ -35,6 +35,7 @@ class Kernel {
 	std::vector<KernelObject> objects;
 	std::vector<Handle> portHandles;
 	std::vector<Handle> mutexHandles;
+	std::vector<Handle> timerHandles;
 
 	// Thread indices, sorted by priority
 	std::vector<int> threadIndices;
@@ -84,6 +85,7 @@ private:
 	void releaseMutex(Mutex* moo);
 	void cancelTimer(Timer* timer);
 	void signalTimer(Handle timerHandle, Timer* timer);
+	void updateTimer(Handle timerHandle, Timer* timer);
 
 	// Wake up the thread with the highest priority out of all threads in the waitlist
 	// Returns the index of the woken up thread
@@ -182,6 +184,14 @@ public:
 	void requireReschedule() { needReschedule = true; }
 
 	void evalReschedule() {
+		for (auto handle : timerHandles) {
+			const auto object = getObject(handle, KernelObjectType::Timer);
+			if (object != nullptr) {
+				Timer* timer = object->getData<Timer>();
+				updateTimer(handle, timer);
+			}
+		}
+
 		if (needReschedule) {
 			needReschedule = false;
 			rescheduleThreads();

include/kernel/kernel_types.hpp

@@ -167,11 +167,13 @@ struct Timer {
 	u64 waitlist;  // Refer to the getWaitlist function below for documentation
 	ResetType resetType = ResetType::OneShot;
 
-    u64 initialDelay; // Number of ns until the timer fires for the first time
-	u64 interval;     // Number of ns until the timer fires for the second and future times
-	bool fired;       // Has this Timer been signalled?
+	u64 startTick;     // CPU tick the timer started
+	u64 currentDelay;  // Number of ns until the timer fires next time
+	u64 interval;      // Number of ns until the timer fires for the second and future times
+	bool fired;        // Has this timer been signalled?
+	bool running;      // Is this timer running or stopped?
 
-	Timer(ResetType type) : resetType(type), initialDelay(0), interval(0), waitlist(0), fired(false) {}
+	Timer(ResetType type) : resetType(type), startTick(0), currentDelay(0), interval(0), waitlist(0), fired(false), running(false) {}
 };
 
 struct MemoryBlock {

src/core/kernel/kernel.cpp

@@ -7,6 +7,7 @@ Kernel::Kernel(CPU& cpu, Memory& mem, GPU& gpu)
 	: cpu(cpu), regs(cpu.regs()), mem(mem), handleCounter(0), serviceManager(regs, mem, gpu, currentProcess, *this) {
 	objects.reserve(512); // Make room for a few objects to avoid further memory allocs later
 	mutexHandles.reserve(8);
+	timerHandles.reserve(8);
 	portHandles.reserve(32);
 	threadIndices.reserve(appResourceLimits.maxThreads);
 
@@ -146,6 +147,7 @@ void Kernel::reset() {
 	}
 	objects.clear();
 	mutexHandles.clear();
+	timerHandles.clear();
 	portHandles.clear();
 	threadIndices.clear();
 	serviceManager.reset();

src/core/kernel/timers.cpp

@@ -1,26 +1,55 @@
 #include "kernel.hpp"
+#include "cpu.hpp"
 
 Handle Kernel::makeTimer(ResetType type) {
 	Handle ret = makeObject(KernelObjectType::Timer);
 	objects[ret].data = new Timer(type);
 
-	if (type == ResetType::Pulse) Helpers::panic("Created pulse timer");
+	if (type == ResetType::Pulse) {
+		Helpers::panic("Created pulse timer");
+	}
 
+	timerHandles.push_back(ret);
 	return ret;
 }
 
+void Kernel::updateTimer(Handle handle, Timer* timer) {
+	if (timer->running) {
+		const u64 currentTicks = cpu.getTicks();
+		u64 elapsedTicks = currentTicks - timer->startTick;
+
+		constexpr double ticksPerSec = double(CPU::ticksPerSec);
+		constexpr double nsPerTick = ticksPerSec / 1000000000.0;
+		const s64 elapsedNs = s64(double(elapsedTicks) * nsPerTick);
+
+		// Timer has fired
+		if (elapsedNs >= timer->currentDelay) {
+			timer->startTick = currentTicks;
+			timer->currentDelay = timer->interval;
+			signalTimer(handle, timer);
+		}
+	}
+}
+
 void Kernel::cancelTimer(Timer* timer) {
+	timer->running = false;
 	// TODO: When we have a scheduler this should properly cancel timer events in the scheduler
 }
 
 void Kernel::signalTimer(Handle timerHandle, Timer* timer) {
 	timer->fired = true;
-	wakeupAllThreads(timer->waitlist, timerHandle);
+	requireReschedule();
 
-	switch (timer->resetType) {
-		case ResetType::OneShot: timer->fired = false; break;
-		case ResetType::Sticky: break;
-		case ResetType::Pulse: Helpers::panic("Signalled pulsing timer"); break;
+	// Check if there's any thread waiting on this event
+	if (timer->waitlist != 0) {
+		wakeupAllThreads(timer->waitlist, timerHandle);
+		timer->waitlist = 0;  // No threads waiting;
+
+		switch (timer->resetType) {
+			case ResetType::OneShot: timer->fired = false; break;
+			case ResetType::Sticky: break;
+			case ResetType::Pulse: Helpers::panic("Signalled pulsing timer"); break;
+		}
 	}
 }
 
@@ -54,8 +83,10 @@ void Kernel::svcSetTimer() {
 
 	Timer* timer = object->getData<Timer>();
 	cancelTimer(timer);
-	timer->initialDelay = initial;
+	timer->currentDelay = initial;
 	timer->interval = interval;
+	timer->running = true;
+	timer->startTick = cpu.getTicks();
 
 	// If the initial delay is 0 then instantly signal the timer
 	if (initial == 0) {
@@ -81,4 +112,16 @@ void Kernel::svcClearTimer() {
 	}
 }
 
-void Kernel::svcCancelTimer() { Helpers::panic("Kernel::CancelTimer"); }
+void Kernel::svcCancelTimer() {
+	Handle handle = regs[0];
+	logSVC("CancelTimer (handle = %X)\n", handle);
+	KernelObject* object = getObject(handle, KernelObjectType::Timer);
+
+	if (object == nullptr) {
+		Helpers::panic("Tried to cancel non-existent timer %X\n", handle);
+		regs[0] = Result::Kernel::InvalidHandle;
+	} else {
+		cancelTimer(object->getData<Timer>());
+		regs[0] = Result::Success;
+	}
+}