[zion] Move more initialization into the ApicTimer class.

zion/interrupt/apic_timer.cpp

@@ -4,11 +4,15 @@
 #include "interrupt/apic.h"
 #include "interrupt/timer.h"
 
+const uint32_t kScheduleFrequency = 20;
 ApicTimer* gApicTimer = nullptr;
 
 void ApicTimer::Init() {
   gApicTimer = new ApicTimer();
   gApicTimer->StartCalibration();
+  asm("sti;");
+  gApicTimer->WaitCalibration();
+  asm("cli;");
 }
 
 void ApicTimer::StartCalibration() {
@@ -33,5 +37,6 @@ void ApicTimer::Calibrate() {
 
 void ApicTimer::FinishCalibration() {
   MaskPit();
-  SetLocalTimer(calculated_frequency_ / 20, LAPIC_TIMER_PERIODIC);
+  SetLocalTimer(calculated_frequency_ / kScheduleFrequency,
+                LAPIC_TIMER_PERIODIC);
 }

zion/interrupt/apic_timer.h

@@ -11,12 +11,6 @@ class ApicTimer {
   // after implementing HPET.
   void Calibrate();
 
-  void WaitCalibration() {
-    while (calculated_frequency_ == 0) {
-      asm("hlt;");
-    }
-  }
-
  private:
   struct Calibration {
     uint32_t initial_measurement = 0;
@@ -29,6 +23,12 @@ class ApicTimer {
   ApicTimer() {}
   void StartCalibration();
   void FinishCalibration();
+
+  void WaitCalibration() {
+    while (calculated_frequency_ == 0) {
+      asm("hlt;");
+    }
+  }
 };
 
 extern ApicTimer* gApicTimer;

zion/zion.cpp

@@ -39,11 +39,7 @@ extern "C" void zion() {
   dbgln("[boot] Init scheduler.");
   ProcessManager::Init();
   Scheduler::Init();
-  // Schedule every 50ms.
   ApicTimer::Init();
-  asm("sti;");
-  gApicTimer->WaitCalibration();
-  asm("cli;");
 
   dbgln("[boot] Loading sys init program.");
   LoadInitProgram();