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Add a start time to sem_tickwait() to account for any elapsed time before the timer is actually started

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This commit is contained in:
Gregory Nutt 2015-08-01 14:57:31 -06:00
parent 030573ba5c
commit ffec6124f2
2 changed files with 31 additions and 9 deletions
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11
include/nuttx/semaphore.h
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@ -94,8 +94,13 @@ extern "C"
*
* Parameters:
* sem - Semaphore object
* ticks - Ticks to wait until the semaphore is posted. If ticks is
* zero, then this function is equivalent to sem_trywait().
* start - The system time that the delay is relative to. If the
* current time is not the same as the start time, then the
* delay will be adjust so that the end time will be the same
* in any event.
* delay - Ticks to wait from the start time until the semaphore is
* posted. If ticks is zero, then this function is equivalent
* to sem_trywait().
*
* Return Value:
* Zero (OK) is returned on success. A negated errno value is returned on
@ -103,7 +108,7 @@ extern "C"
*
****************************************************************************/
int sem_tickwait(FAR sem_t *sem, uint32_t ticks);
int sem_tickwait(FAR sem_t *sem, uint32_t start, uint32_t delay);
#undef EXTERN
#ifdef __cplusplus

29
sched/semaphore/sem_tickwait.c
View File

@ -47,6 +47,7 @@
#include <debug.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#include <nuttx/wdog.h>
#include "sched/sched.h"
@ -65,19 +66,25 @@
*
* Parameters:
* sem - Semaphore object
* ticks - Ticks to wait until the semaphore is posted. If ticks is
* zero, then this function is equivalent to sem_trywait().
* start - The system time that the delay is relative to. If the
* current time is not the same as the start time, then the
* delay will be adjust so that the end time will be the same
* in any event.
* delay - Ticks to wait from the start time until the semaphore is
* posted. If ticks is zero, then this function is equivalent
* to sem_trywait().
*
* Return Value:
* Zero (OK) is returned on success. A negated errno value is retuend on
* Zero (OK) is returned on success. A negated errno value is returned on
* failure. -ETIMEDOUT is returned on the timeout condition.
*
****************************************************************************/
int sem_tickwait(FAR sem_t *sem, uint32_t ticks)
int sem_tickwait(FAR sem_t *sem, uint32_t start, uint32_t delay)
{
FAR struct tcb_s *rtcb = (FAR struct tcb_s *)g_readytorun.head;
irqstate_t flags;
uint32_t elapsed;
int ret;
DEBUGASSERT(sem |= NULL && up_interrupt_context() == false &&
@ -118,7 +125,7 @@ int sem_tickwait(FAR sem_t *sem, uint32_t ticks)
* with a valid timeout.
*/
if (ticks == 0)
if (delay == 0)
{
/* Return the errno from sem_trywait() */
@ -126,9 +133,19 @@ int sem_tickwait(FAR sem_t *sem, uint32_t ticks)
goto errout_with_irqdisabled;
}
/* Adjust the delay for any time since the delay was calculated */
elapsed = clock_systimer() - start;
if (elapsed >= (UINT32_MAX / 2) || elapsed >= delay)
{
return -ETIMEDOUT;
}
delay -= elapsed;
/* Start the watchdog with interrupts still disabled */
(void)wd_start(rtcb->waitdog, ticks, (wdentry_t)sem_timeout, 1, getpid());
(void)wd_start(rtcb->waitdog, delay, (wdentry_t)sem_timeout, 1, getpid());
/* Now perform the blocking wait */