Added PIT support, sleep() exists!

src/kernel/main.c

@@ -3,6 +3,7 @@
 #include "isrs.h"
 #include "irq.h"
 #include "keyboard.h"
+#include "timer.h"
 #include "system.h"
 
 void main() {
@@ -13,6 +14,8 @@ void main() {
     sti();
 
     setupKeyboard();
+    setupTimer();
+    timerPhase(100); // 1 tick per 10ms
 
     clear(0x0f);
     print("kern.\n\n", 0x0f);

src/kernel/string.c

@@ -1,5 +1,6 @@
 #include "string.h"
 
+// Source: http://www.strudel.org.uk/itoa/
 char* itoa(uint32_t val, uint8_t base) {
     static char buf[32] = { 0 };
 

src/kernel/timer.c

@@ -0,0 +1,31 @@
+#include "timer.h"
+#include "stdint.h"
+#include "idt.h"
+#include "irq.h"
+#include "system.h"
+
+uint32_t timerTicks = 0;
+
+void timerHandler() {
+    timerTicks++;
+}
+
+void setupTimer() {
+    installIrqHandler(0, timerHandler);
+}
+
+// Source: https://en.wikibooks.org/wiki/X86_Assembly/Programmable_Interval_Timer
+void timerPhase(uint32_t hz) {
+    uint16_t div = INPUT_CLK / hz;
+
+    outb(0x43, 0x36); // Tell PIT that we're setting channel 0
+    outb(0x40, div & 0xff); // Low byte
+    outb(0X40, div >> 8); // High byte
+}
+
+void sleep(uint32_t ticks) {
+    uint32_t eticks = ticks + timerTicks;
+    
+    while (timerTicks != eticks); // Should avoid overflows unlike '<'
+}
+

src/kernel/timer.h

@@ -0,0 +1,12 @@
+#ifndef TIMER_H
+#define TIMER_H
+
+#include "stdint.h"
+
+#define INPUT_CLK 1193180
+
+void setupTimer();
+void sleep(uint32_t ticks);
+void timerPhase(uint32_t hz);
+
+#endif