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
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)
{
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)
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));
+}