Add handy functions for handling non recurrent timeouts.

[bertos.git] / bertos / drv / timer.c

diff --git a/bertos/drv/timer.c b/bertos/drv/timer.c
index 60494413276918af234d3a802dbb8177c6fd413d..a64a839ca76ea5415b5f488c3edaefd0695e10cd 100644 (file)
--- a/bertos/drv/timer.c
+++ b/bertos/drv/timer.c
@@ -52,6 +52,8 @@
 #include <cpu/irq.h>
 #include <cpu/power.h> // cpu_relax()
 
+#include <kern/proc_p.h> // proc_decQuantun()
+
 /*
  * Include platform-specific binding code if we're hosted.
  * Try the CPU specific one for bare-metal environments.
@@ -125,10 +127,6 @@ INLINE void timer_addToList(Timer *timer, List *queue)
        ASSERT(timer->magic != TIMER_MAGIC_ACTIVE);
        DB(timer->magic = TIMER_MAGIC_ACTIVE;)
 
-
-       /* Calculate expiration time for this timer */
-       timer->tick = _clock + timer->_delay;
-
        /*
         * Search for the first node whose expiration time is
         * greater than the timer we want to add.
@@ -160,7 +158,12 @@ INLINE void timer_addToList(Timer *timer, List *queue)
  */
 void timer_add(Timer *timer)
 {
-       ATOMIC(timer_addToList(timer, &timers_queue));
+       ATOMIC(
+               /* Calculate expiration time for this timer */
+               timer->tick = _clock + timer->_delay;
+
+               timer_addToList(timer, &timers_queue);
+       );
 }
 
 /**
@@ -210,9 +213,18 @@ INLINE void timer_poll(List *queue)
  */
 void synctimer_add(Timer *timer, List *queue)
 {
+       timer->tick = timer_clock() + timer->_delay;
+
+       timer_addToList(timer, queue);
+}
+
+void synctimer_readd(Timer *timer, List *queue)
+{
+       timer->tick += timer->_delay;
        timer_addToList(timer, queue);
 }
 
+
 /**
  * Simple synchronous timer based scheduler polling routine.
  *
@@ -240,30 +252,34 @@ void synctimer_poll(List *queue)
 
 /**
  * Wait for the specified amount of timer ticks.
+ *
+ * \note Sleeping while preemption is disabled fallbacks to a busy wait sleep.
  */
 void timer_delayTicks(ticks_t delay)
 {
        /* We shouldn't sleep with interrupts disabled */
        IRQ_ASSERT_ENABLED();
 
-#if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
+#if CONFIG_KERN_SIGNALS
        Timer t;
-
-       ASSERT(!sig_check(SIG_SINGLE));
-       timer_setSignal(&t, proc_current(), SIG_SINGLE);
-       timer_setDelay(&t, delay);
-       timer_add(&t);
-       sig_wait(SIG_SINGLE);
-
-#else /* !CONFIG_KERN_SIGNALS */
-
-       ticks_t start = timer_clock();
-
-       /* Busy wait */
-       while (timer_clock() - start < delay)
-               cpu_relax();
-
+       DB(t.magic = TIMER_MAGIC_INACTIVE;)
+       if (proc_preemptAllowed())
+       {
+               ASSERT(!sig_check(SIG_SINGLE));
+               timer_setSignal(&t, proc_current(), SIG_SINGLE);
+               timer_setDelay(&t, delay);
+               timer_add(&t);
+               sig_wait(SIG_SINGLE);
+       }
+       else
 #endif /* !CONFIG_KERN_SIGNALS */
+       {
+               ticks_t start = timer_clock();
+
+               /* Busy wait */
+               while (timer_clock() - start < delay)
+                       cpu_relax();
+       }
 }
 
 
@@ -280,15 +296,30 @@ void timer_busyWait(hptime_t delay)
        hptime_t now, prev = timer_hw_hpread();
        hptime_t delta;
 
-       for(;;)
+       for (;;)
        {
                now = timer_hw_hpread();
                /*
-                * We rely on hptime_t being unsigned here to
-                * reduce the modulo to an AND in the common
-                * case of TIMER_HW_CNT.
+                * The timer counter may wrap here and "prev" can become
+                * greater than "now". So, be sure to always evaluate a
+                * coherent timer difference:
+                *
+                * 0     prev            now   TIMER_HW_CNT
+                * |_____|_______________|_____|
+                *        ^^^^^^^^^^^^^^^
+                * delta = now - prev
+                *
+                * 0     now             prev  TIMER_HW_CNT
+                * |_____|_______________|_____|
+                *  ^^^^^                 ^^^^^
+                * delta = (TIMER_HW_CNT - prev) + now
+                *
+                * NOTE: TIMER_HW_CNT can be any value, not necessarily a power
+                * of 2. For this reason the "%" operator is not suitable for
+                * the generic case.
                 */
-               delta = (now - prev) % TIMER_HW_CNT;
+               delta = (now < prev) ? ((hptime_t)TIMER_HW_CNT - prev + now) :
+                                               (now - prev);
                if (delta >= delay)
                        break;
                delay -= delta;
@@ -315,7 +346,6 @@ void timer_delayHp(hptime_t delay)
 }
 #endif /* CONFIG_TIMER_UDELAY */
 
-
 /**
  * Timer interrupt handler. Find soft timers expired and
  * trigger corresponding events.
@@ -340,16 +370,19 @@ DEFINE_TIMER_ISR
 
        TIMER_STROBE_ON;
 
-       /* Perform hw IRQ handling */
-       timer_hw_irq();
-
        /* Update the master ms counter */
        ++_clock;
 
+       /* Update the current task's quantum (if enabled). */
+       proc_decQuantum();
+
        #if CONFIG_TIMER_EVENTS
                timer_poll(&timers_queue);
        #endif
 
+       /* Perform hw IRQ handling */
+       timer_hw_irq();
+
        TIMER_STROBE_OFF;
 }
 
@@ -378,17 +411,14 @@ void timer_init(void)
 }
 
 
-#if (ARCH & ARCH_EMUL)
+#if (ARCH & ARCH_EMUL) || (CPU_ARM_AT91)
 /**
- * Stop timer (only used by emulator)
+ * Stop timer
  */
 void timer_cleanup(void)
 {
        MOD_CLEANUP(timer);
 
        timer_hw_cleanup();
-
-       // Hmmm... apparently, the demo app does not cleanup properly
-       //ASSERT(LIST_EMPTY(&timers_queue));
 }
-#endif /* ARCH_EMUL */
+#endif