X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?p=pintos-anon;a=blobdiff_plain;f=src%2Fdevices%2Ftimer.c;h=70234a808844e425d8309f6cd04c09ce11ad230e;hp=a4521de86e32b91b7a939f68e06d6f6c7a0b83b3;hb=cc5c971c3cc498d528a2f74f4dc2f8e27a690311;hpb=500278652b3d3ec6ba08c150e749b65ca4a5d208

diff --git a/src/devices/timer.c b/src/devices/timer.c
index a4521de..70234a8 100644
--- a/src/devices/timer.c
+++ b/src/devices/timer.c
@@ -28,6 +28,7 @@ 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
@@ -92,7 +93,8 @@ 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) 
 {
@@ -103,27 +105,69 @@ 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) 
@@ -195,10 +239,17 @@ 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)); 
+}