feat(drivers): remap PIC and drive PIT at 100 Hz

src/pit.c

@@ -0,0 +1,34 @@
+#include "pit.h"
+#include "ports.h"
+
+#define pitChannel0 0x40
+#define pitCommand 0x43
+#define pitBaseFrequency 1193182
+
+static volatile uint64 tickCount;
+static uint32 configuredFrequency;
+
+void pitInit(uint32 frequency)
+{
+    configuredFrequency = frequency;
+    uint32 divisor = pitBaseFrequency / frequency;
+
+    outb(pitCommand, 0x36);
+    outb(pitChannel0, (uint8)(divisor & 0xFF));
+    outb(pitChannel0, (uint8)((divisor >> 8) & 0xFF));
+}
+
+void pitTick(void)
+{
+    tickCount++;
+}
+
+uint64 pitTicks(void)
+{
+    return tickCount;
+}
+
+uint32 pitFrequency(void)
+{
+    return configuredFrequency;
+}