1 files changed, 91 insertions, 0 deletions
diff --git a/src/kernel/task/timer.cpp b/src/kernel/task/timer.cpp
new file mode 100644
index 0000000..05c4550
--- /dev/null
+++ b/src/kernel/task/timer.cpp
@@ -0,0 +1,91 @@
+#include "timer.h"
+#include "task.h"
+#include "idt.h"
+#include <mem/mem.h>
+#include <core/sys.h>
+#include <core/monitor.h>
+
+static uint32_t tick = 0, frequency = 0, uptime = 0;
+
+static void timer_callback(registers *regs);
+static void timer_wakeUpSleepingThreads();
+
+/*	Called by kmain. Sets up the PIT and the IRQ0 handler. */
+void timer_init(uint32_t freq) {
+	frequency = freq;
+
+	idt_handleIrq(0, timer_callback);
+
+	uint32_t divisor = 1193180 / freq;
+
+	outb(0x43, 0x36);	//Command byte
+
+	uint8_t l = (divisor & 0xFF), h = (divisor >> 8);
+	outb(0x40, l);
+	outb(0x40, h);
+
+	monitor_write("[PIT] ");
+}
+
+/*	Accessor function to get machine uptime. */
+uint32_t timer_uptime() { return uptime; }
+
+/*	Accessor function, gets uptime in miliseconds. */
+uint32_t timer_time() {
+	return (uptime * 1000) + (tick * 1000 / frequency);
+}
+
+/*	Called when IRQ0 fires. Updates the uptime variable.
+	DOES NOT provoke a task switch. The task switch is called in idt.c (IRQ handler). */
+void timer_callback(registers *regs) {
+	tick++;
+	if (tick == frequency) {
+		uptime++;
+		tick = 0;
+	}
+	timer_wakeUpSleepingThreads();
+}
+
+//************************************************	SLEEP FUNCTIONS *****************
+
+static struct sleeping_thread {
+	uint32_t wakeup_time;
+	struct thread *thread;
+	sleeping_thread *next;
+} *sleeping_threads = 0;
+
+/*	Makes the current thread sleep. */
+void thread_sleep(uint32_t msecs) {
+	if (current_thread == 0) return;
+	// Create the sleeping_thread structure
+	sleeping_thread *sf = (sleeping_thread*)kmalloc(sizeof(sleeping_thread)), *tmp;
+	sf->wakeup_time = timer_time() + msecs;
+	sf->thread = current_thread;
+	//Insert it at the right place
+	if (sleeping_threads == 0 || sleeping_threads->wakeup_time >= sf->wakeup_time) {
+		sf->next = sleeping_threads;
+		sleeping_threads = sf;
+	} else {
+		tmp = sleeping_threads;
+		while (1) {
+			if (tmp->next == 0 || tmp->next->wakeup_time >= sf->wakeup_time) {
+				sf->next = tmp->next;
+				tmp->next = sf;
+				break;
+			}
+			tmp = tmp->next;
+		}
+	}
+
+	thread_goInactive();
+}
+
+void timer_wakeUpSleepingThreads() {
+	uint32_t time = timer_time();
+	while (sleeping_threads != 0 && sleeping_threads->wakeup_time <= time) {
+		sleeping_thread *tmp = sleeping_threads;
+		thread_wakeUp(tmp->thread);
+		sleeping_threads = tmp->next;
+		kfree(tmp);
+	}
+}