Add PC speaker driver and connect it to '\a' in the VGA console.

[pintos-anon] / src / devices / timer.c

diff --git a/src/devices/timer.c b/src/devices/timer.c
index c8c41d55cf412948eb71a04b52c748f0c554465d..c97667f56bfcd5d9bd70862c7ff3ca2047f8f706 100644 (file)
--- a/src/devices/timer.c
+++ b/src/devices/timer.c
@@ -3,8 +3,9 @@
 #include <inttypes.h>
 #include <round.h>
 #include <stdio.h>
+#include "devices/pit.h"
 #include "threads/interrupt.h"
-#include "threads/io.h"
+#include "threads/synch.h"
 #include "threads/thread.h"
   
 /* See [8254] for hardware details of the 8254 timer chip. */
@@ -17,7 +18,7 @@
 #endif
 
 /* Number of timer ticks since OS booted. */
-static volatile int64_t ticks;
+static int64_t ticks;
 
 /* Number of loops per timer tick.
    Initialized by timer_calibrate(). */
@@ -27,21 +28,14 @@ static intr_handler_func timer_interrupt;
 static bool too_many_loops (unsigned loops);
 static void busy_wait (int64_t loops);
 static void real_time_sleep (int64_t num, int32_t denom);
+static void real_time_delay (int64_t num, int32_t denom);
 
-/* Sets up the 8254 Programmable Interval Timer (PIT) to
-   interrupt PIT_FREQ times per second, and registers the
-   corresponding interrupt. */
+/* Sets up the timer to interrupt TIMER_FREQ times per second,
+   and registers the corresponding interrupt. */
 void
 timer_init (void) 
 {
-  /* 8254 input frequency divided by TIMER_FREQ, rounded to
-     nearest. */
-  uint16_t count = (1193180 + TIMER_FREQ / 2) / TIMER_FREQ;
-
-  outb (0x43, 0x34);    /* CW: counter 0, LSB then MSB, mode 2, binary. */
-  outb (0x40, count & 0xff);
-  outb (0x40, count >> 8);
-
+  pit_configure_channel (0, 2, TIMER_FREQ);
   intr_register_ext (0x20, timer_interrupt, "8254 Timer");
 }
 
@@ -57,8 +51,11 @@ timer_calibrate (void)
   /* Approximate loops_per_tick as the largest power-of-two
      still less than one timer tick. */
   loops_per_tick = 1u << 10;
-  while (!too_many_loops (loops_per_tick << 1))
-    loops_per_tick <<= 1;
+  while (!too_many_loops (loops_per_tick << 1)) 
+    {
+      loops_per_tick <<= 1;
+      ASSERT (loops_per_tick != 0);
+    }
 
   /* Refine the next 8 bits of loops_per_tick. */
   high_bit = loops_per_tick;
@@ -76,6 +73,7 @@ timer_ticks (void)
   enum intr_level old_level = intr_disable ();
   int64_t t = ticks;
   intr_set_level (old_level);
+  barrier ();
   return t;
 }
 
@@ -87,7 +85,8 @@ timer_elapsed (int64_t then)
   return timer_ticks () - then;
 }
 
-/* Suspends execution for approximately TICKS timer ticks. */
+/* Sleeps for approximately TICKS timer ticks.  Interrupts must
+   be turned on. */
 void
 timer_sleep (int64_t ticks) 
 {
@@ -98,27 +97,69 @@ timer_sleep (int64_t ticks)
     thread_yield ();
 }
 
-/* Suspends execution for approximately MS milliseconds. */
+/* Sleeps for approximately MS milliseconds.  Interrupts must be
+   turned on. */
 void
 timer_msleep (int64_t ms) 
 {
   real_time_sleep (ms, 1000);
 }
 
-/* Suspends execution for approximately US microseconds. */
+/* Sleeps for approximately US microseconds.  Interrupts must be
+   turned on. */
 void
 timer_usleep (int64_t us) 
 {
   real_time_sleep (us, 1000 * 1000);
 }
 
-/* Suspends execution for approximately NS nanoseconds. */
+/* Sleeps for approximately NS nanoseconds.  Interrupts must be
+   turned on. */
 void
 timer_nsleep (int64_t ns) 
 {
   real_time_sleep (ns, 1000 * 1000 * 1000);
 }
 
+/* Busy-waits for approximately MS milliseconds.  Interrupts need
+   not be turned on.
+
+   Busy waiting wastes CPU cycles, and busy waiting with
+   interrupts off for the interval between timer ticks or longer
+   will cause timer ticks to be lost.  Thus, use timer_msleep()
+   instead if interrupts are enabled. */
+void
+timer_mdelay (int64_t ms) 
+{
+  real_time_delay (ms, 1000);
+}
+
+/* Sleeps for approximately US microseconds.  Interrupts need not
+   be turned on.
+
+   Busy waiting wastes CPU cycles, and busy waiting with
+   interrupts off for the interval between timer ticks or longer
+   will cause timer ticks to be lost.  Thus, use timer_usleep()
+   instead if interrupts are enabled. */
+void
+timer_udelay (int64_t us) 
+{
+  real_time_delay (us, 1000 * 1000);
+}
+
+/* Sleeps execution for approximately NS nanoseconds.  Interrupts
+   need not be turned on.
+
+   Busy waiting wastes CPU cycles, and busy waiting with
+   interrupts off for the interval between timer ticks or longer
+   will cause timer ticks to be lost.  Thus, use timer_nsleep()
+   instead if interrupts are enabled.*/
+void
+timer_ndelay (int64_t ns) 
+{
+  real_time_delay (ns, 1000 * 1000 * 1000);
+}
+
 /* Prints timer statistics. */
 void
 timer_print_stats (void) 
@@ -139,18 +180,17 @@ timer_interrupt (struct intr_frame *args UNUSED)
 static bool
 too_many_loops (unsigned loops) 
 {
-  int64_t start;
-
   /* Wait for a timer tick. */
-  start = ticks;
+  int64_t start = ticks;
   while (ticks == start)
-    continue;
+    barrier ();
 
   /* Run LOOPS loops. */
   start = ticks;
   busy_wait (loops);
 
   /* If the tick count changed, we iterated too long. */
+  barrier ();
   return start != ticks;
 }
 
@@ -165,7 +205,7 @@ static void NO_INLINE
 busy_wait (int64_t loops) 
 {
   while (loops-- > 0)
-    continue;
+    barrier ();
 }
 
 /* Sleep for approximately NUM/DENOM seconds. */
@@ -191,10 +231,17 @@ real_time_sleep (int64_t num, int32_t denom)
   else 
     {
       /* Otherwise, use a busy-wait loop for more accurate
-         sub-tick timing.  We scale the numerator and denominator
-         down by 1000 to avoid the possibility of overflow. */
-      ASSERT (denom % 1000 == 0);
-      busy_wait (loops_per_tick * num / 1000 * TIMER_FREQ / (denom / 1000)); 
+         sub-tick timing. */
+      real_time_delay (num, denom); 
     }
 }
 
+/* Busy-wait for approximately NUM/DENOM seconds. */
+static void
+real_time_delay (int64_t num, int32_t denom)
+{
+  /* Scale the numerator and denominator down by 1000 to avoid
+     the possibility of overflow. */
+  ASSERT (denom % 1000 == 0);
+  busy_wait (loops_per_tick * num / 1000 * TIMER_FREQ / (denom / 1000)); 
+}