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- #include "devices/timer.h"
- #include <debug.h>
- #include <inttypes.h>
- #include <round.h>
- #include <stdio.h>
- #include "devices/pit.h"
- #include "threads/interrupt.h"
- #include "threads/synch.h"
- #include "threads/thread.h"
- /* See [8254] for hardware details of the 8254 timer chip. */
- #if TIMER_FREQ < 19
- #error 8254 timer requires TIMER_FREQ >= 19
- #endif
- #if TIMER_FREQ > 1000
- #error TIMER_FREQ <= 1000 recommended
- #endif
- /* Number of timer ticks since OS booted. */
- static int64_t ticks;
- /* Number of loops per timer tick.
- Initialized by timer_calibrate(). */
- static unsigned loops_per_tick;
- 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);
- static void wakeup_elapsed_time_thread(struct thread* thread , void* aux);
- /* Sets up the timer to interrupt TIMER_FREQ times per second,
- and registers the corresponding interrupt. */
- void
- timer_init (void)
- {
- pit_configure_channel (0, 2, TIMER_FREQ);
- intr_register_ext (0x20, timer_interrupt, "8254 Timer");
- }
- /* Calibrates loops_per_tick, used to implement brief delays. */
- void
- timer_calibrate (void)
- {
- unsigned high_bit, test_bit;
- ASSERT (intr_get_level () == INTR_ON);
- printf ("Calibrating timer... ");
- /* 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;
- ASSERT (loops_per_tick != 0);
- }
- /* Refine the next 8 bits of loops_per_tick. */
- high_bit = loops_per_tick;
- for (test_bit = high_bit >> 1; test_bit != high_bit >> 10; test_bit >>= 1)
- if (!too_many_loops (high_bit | test_bit))
- loops_per_tick |= test_bit;
- printf ("%'"PRIu64" loops/s.\n", (uint64_t) loops_per_tick * TIMER_FREQ);
- }
- /* Returns the number of timer ticks since the OS booted. */
- int64_t
- timer_ticks (void)
- {
- enum intr_level old_level = intr_disable ();
- int64_t t = ticks;
- intr_set_level (old_level);
- return t;
- }
- /* Returns the number of timer ticks elapsed since THEN, which
- should be a value once returned by timer_ticks(). */
- int64_t
- timer_elapsed (int64_t then)
- {
- return timer_ticks () - then;
- }
- /* Sleeps for approximately TICKS timer ticks. Interrupts must
- be turned on. */
- void
- timer_sleep (int64_t ticks)
- {
- int64_t start = timer_ticks ();
- /*set wake up time for thread to be blocked in order to allow
- handler to check if time elapsed for the thread */
- ASSERT (intr_get_level () == INTR_ON);
- /* while (timer_elapsed (start) < ticks)
- thread_yield ();*/
- /*we will disable interrupt bec the thread might set his starting time then interrupted before it block itself so
- it will be sent to ready queue and this is fault it must be ent to blocked*/
- enum intr_level old_level;
- old_level = intr_disable();
- //
- // struct thread *cur = thread_current ();
- thread_current()->wakeup_time = start + ticks;
- thread_block();
- intr_set_level(old_level);
- intr_enable();
- }
- /* Sleeps for approximately MS milliseconds. Interrupts must be
- turned on. */
- void
- timer_msleep (int64_t ms)
- {
- real_time_sleep (ms, 1000);
- }
- /* Sleeps for approximately US microseconds. Interrupts must be
- turned on. */
- void
- timer_usleep (int64_t us)
- {
- real_time_sleep (us, 1000 * 1000);
- }
- /* 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)
- {
- printf ("Timer: %"PRId64" ticks\n", timer_ticks ());
- }
- /* Timer interrupt handler. */
- static void
- timer_interrupt (struct intr_frame *args UNUSED)
- {
- ticks++;
- thread_tick ();
- thread_foreach(wakeup_elapsed_time_thread,0);
- }
- /* Returns true if LOOPS iterations waits for more than one timer
- tick, otherwise false. */
- static bool
- too_many_loops (unsigned loops)
- {
- /* Wait for a timer tick. */
- int64_t start = ticks;
- while (ticks == start)
- barrier ();
- /* Run LOOPS loops. */
- start = ticks;
- busy_wait (loops);
- /* If the tick count changed, we iterated too long. */
- barrier ();
- return start != ticks;
- }
- /* Iterates through a simple loop LOOPS times, for implementing
- brief delays.
- Marked NO_INLINE because code alignment can significantly
- affect timings, so that if this function was inlined
- differently in different places the results would be difficult
- to predict. */
- static void NO_INLINE
- busy_wait (int64_t loops)
- {
- while (loops-- > 0)
- barrier ();
- }
- /* Sleep for approximately NUM/DENOM seconds. */
- static void
- real_time_sleep (int64_t num, int32_t denom)
- {
- /* Convert NUM/DENOM seconds into timer ticks, rounding down.
- (NUM / DENOM) s
- ---------------------- = NUM * TIMER_FREQ / DENOM ticks.
- 1 s / TIMER_FREQ ticks
- */
- int64_t ticks = num * TIMER_FREQ / denom;
- ASSERT (intr_get_level () == INTR_ON);
- if (ticks > 0)
- {
- /* We're waiting for at least one full timer tick. Use
- timer_sleep() because it will yield the CPU to other
- processes. */
- timer_sleep (ticks);
- }
- else
- {
- /* Otherwise, use a busy-wait loop for more accurate
- 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));
- }
- static void wakeup_elapsed_time_thread(struct thread* thread , void* aux){
- //check if thread is blocked and it's time waiting has elapsed then it has to
- //be unblocked.
- int64_t current_time = timer_ticks ();
- if( thread->status == THREAD_BLOCKED && current_time >= thread->wakeup_time){
- thread_unblock(thread);
- }
- }
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