Set up initial task switching (ring0 only)

src/kernel/scheduler.h

@@ -0,0 +1,44 @@
+#pragma once
+/// \file scheduler.h
+/// The task scheduler and related definitions
+#include "kutil/memory.h"
+#include "kutil/vector.h"
+
+class lapic;
+
+
+struct process
+{
+	uint16_t pid;
+	addr_t rsp;
+};
+
+
+/// The task scheduler
+class scheduler
+{
+public:
+	/// Constructor.
+	/// \arg apic  Pointer to the local APIC object
+	scheduler(lapic *apic);
+
+	/// Start the scheduler working. This may involve starting
+	/// timer interrupts or other preemption methods.
+	void start();
+
+	/// Handle a timer tick
+	/// \arg rsp0  The stack pointer of the current interrupt handler
+	/// \returns   The stack pointer to handler to switch to
+	addr_t tick(addr_t rsp0);
+
+	/// Get a reference to the system scheduler
+	/// \returns  A reference to the global system scheduler
+	static scheduler & get() { return s_instance; }
+
+private:
+	lapic *m_apic;
+	kutil::vector<process> m_processes;
+	uint16_t m_current;
+
+	static scheduler s_instance;
+};