Rewrite init app in C, introduce MSL (MOP3 System Library)

kernel/amd64/hpet.c

@@ -28,8 +28,8 @@
 static bool hpet_32bits = 1;
 /// Physical address for HPET MMIO
 static uintptr_t hpet_paddr;
-/// HPET nanoseconds for conversion
-static uint64_t hpet_clock_nano;
+/// HPET period in femtoseconds
+static uint64_t hpet_period_fs;
 /// Lock, which protects concurrent access. See \ref amd64/smp.c
 static spin_lock_t hpet_lock = SPIN_LOCK_INIT;
 
@@ -54,32 +54,22 @@ static void amd64_hpet_write (uint32_t reg, uint64_t value) {
 /// Read current value of \ref HPET_MCVR register.
 static uint64_t amd64_hpet_timestamp (void) { return amd64_hpet_read (HPET_MCVR); }
 
-/** 
- * @brief Get current HPET timestamp in nanoseconds
- *
- * @param lock
- *  if true, hold \ref hpet_lock
- */
-uint64_t amd64_hpet_current_nano (bool lock) {
-  if (lock)
-    spin_lock (&hpet_lock);
-
-  uint64_t t = amd64_hpet_timestamp () * hpet_clock_nano;
-
-  if (lock)
-    spin_unlock (&hpet_lock);
-
-  return t;
-}
-
 /// Sleep for a given amount of microseconds. This time can last longer due to \ref hpet_lock being held.
 void amd64_hpet_sleep_micro (uint64_t us) {
   spin_lock (&hpet_lock);
 
   uint64_t start = amd64_hpet_timestamp ();
-  uint64_t conv = us * 1000;
-  while (((amd64_hpet_timestamp () - start) * hpet_clock_nano) < conv)
+  uint64_t target_fs = us * 1000000000ULL;
+  
+  for (;;) {
+    uint64_t current = amd64_hpet_timestamp ();
+    uint64_t dt = current - start;
+
+    if ((dt * hpet_period_fs) >= target_fs)
+      break;
+
     __asm__ volatile ("pause" ::: "memory");
+  }
 
   spin_unlock (&hpet_lock);
 }
@@ -114,7 +104,5 @@ void amd64_hpet_init (void) {
     gcidr = (((uint64_t)high << 32) | low);
   }
 
-  uint64_t period_fs = (gcidr >> 32);
-
-  hpet_clock_nano = period_fs / 1000000;
+  hpet_period_fs = (gcidr >> 32);
 }