?? os_mutex.c
字號:
* time is directly proportional to the number of tasks waiting on the mutex.
*
* 3) Because ALL tasks pending on the mutex will be readied, you MUST be careful because the
* resource(s) will no longer be guarded by the mutex.
*
* 4) IMPORTANT: In the 'OS_DEL_ALWAYS' case, we assume that the owner of the Mutex (if there
* is one) is ready-to-run and is thus NOT pending on another kernel object or
* has delayed itself. In other words, if a task owns the mutex being deleted,
* that task will be made ready-to-run at its original priority.
*********************************************************************************************************
*/
#if OS_MUTEX_DEL_EN
OS_EVENT *OSMutexDel (OS_EVENT *pevent, INT8U opt, INT8U *err)
{
BOOLEAN tasks_waiting;
OS_EVENT *pevent_return;
INT8U pip; /* Priority inheritance priority */
INT8U prio;
OS_TCB *ptcb;
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0;
#endif
#if OS_ARG_CHK_EN > 0
if (err == (INT8U *)0) { /* Validate 'err' */
return ((OS_EVENT *)0);
}
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*err = OS_ERR_PEVENT_NULL;
return ((OS_EVENT *)0);
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */
*err = OS_ERR_EVENT_TYPE;
return (pevent);
}
if (OSIntNesting > 0) { /* See if called from ISR ... */
*err = OS_ERR_DEL_ISR; /* ... can't DELETE from an ISR */
return (pevent);
}
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0) { /* See if any tasks waiting on mutex */
tasks_waiting = OS_TRUE; /* Yes */
} else {
tasks_waiting = OS_FALSE; /* No */
}
switch (opt) {
case OS_DEL_NO_PEND: /* DELETE MUTEX ONLY IF NO TASK WAITING --- */
if (tasks_waiting == OS_FALSE) {
#if OS_EVENT_NAME_SIZE > 1
pevent->OSEventName[0] = '?'; /* Unknown name */
pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
pip = (INT8U)(pevent->OSEventCnt >> 8);
OSTCBPrioTbl[pip] = (OS_TCB *)0; /* Free up the PIP */
pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */
pevent->OSEventCnt = 0;
OSEventFreeList = pevent;
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;
pevent_return = (OS_EVENT *)0; /* Mutex has been deleted */
} else {
OS_EXIT_CRITICAL();
*err = OS_ERR_TASK_WAITING;
pevent_return = pevent;
}
break;
case OS_DEL_ALWAYS: /* ALWAYS DELETE THE MUTEX ---------------- */
pip = (INT8U)(pevent->OSEventCnt >> 8); /* Get PIP of mutex */
prio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8); /* Get owner's original prio */
ptcb = (OS_TCB *)pevent->OSEventPtr;
if (ptcb != (OS_TCB *)0) { /* See if any task owns the mutex */
if (ptcb->OSTCBPrio == pip) { /* See if original prio was changed */
OSMutex_RdyAtPrio(ptcb, prio); /* Yes, Restore the task's original prio */
}
}
while (pevent->OSEventGrp != 0) { /* Ready ALL tasks waiting for mutex */
(void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MUTEX);
}
#if OS_EVENT_NAME_SIZE > 1
pevent->OSEventName[0] = '?'; /* Unknown name */
pevent->OSEventName[1] = OS_ASCII_NUL;
#endif
pip = (INT8U)(pevent->OSEventCnt >> 8);
OSTCBPrioTbl[pip] = (OS_TCB *)0; /* Free up the PIP */
pevent->OSEventType = OS_EVENT_TYPE_UNUSED;
pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */
pevent->OSEventCnt = 0;
OSEventFreeList = pevent; /* Get next free event control block */
OS_EXIT_CRITICAL();
if (tasks_waiting == OS_TRUE) { /* Reschedule only if task(s) were waiting */
OS_Sched(); /* Find highest priority task ready to run */
}
*err = OS_NO_ERR;
pevent_return = (OS_EVENT *)0; /* Mutex has been deleted */
break;
default:
OS_EXIT_CRITICAL();
*err = OS_ERR_INVALID_OPT;
pevent_return = pevent;
break;
}
return (pevent_return);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* PEND ON MUTUAL EXCLUSION SEMAPHORE
*
* Description: This function waits for a mutual exclusion semaphore.
*
* Arguments : pevent is a pointer to the event control block associated with the desired
* mutex.
*
* timeout is an optional timeout period (in clock ticks). If non-zero, your task will
* wait for the resource up to the amount of time specified by this argument.
* If you specify 0, however, your task will wait forever at the specified
* mutex or, until the resource becomes available.
*
* err is a pointer to where an error message will be deposited. Possible error
* messages are:
* OS_NO_ERR The call was successful and your task owns the mutex
* OS_TIMEOUT The mutex was not available within the specified time.
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a mutex
* OS_ERR_PEVENT_NULL 'pevent' is a NULL pointer
* OS_ERR_PEND_ISR If you called this function from an ISR and the result
* would lead to a suspension.
* OS_ERR_PIP_LOWER If the priority of the task that owns the Mutex is
* HIGHER (i.e. a lower number) than the PIP. This error
* indicates that you did not set the PIP higher (lower
* number) than ALL the tasks that compete for the Mutex.
* Unfortunately, this is something that could not be
* detected when the Mutex is created because we don't know
* what tasks will be using the Mutex.
*
* Returns : none
*
* Note(s) : 1) The task that owns the Mutex MUST NOT pend on any other event while it owns the mutex.
*
* 2) You MUST NOT change the priority of the task that owns the mutex
*********************************************************************************************************
*/
void OSMutexPend (OS_EVENT *pevent, INT16U timeout, INT8U *err)
{
INT8U pip; /* Priority Inheritance Priority (PIP) */
INT8U mprio; /* Mutex owner priority */
BOOLEAN rdy; /* Flag indicating task was ready */
OS_TCB *ptcb;
OS_EVENT *pevent2;
INT8U y;
#if OS_CRITICAL_METHOD == 3 /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0;
#endif
#if OS_ARG_CHK_EN > 0
if (err == (INT8U *)0) { /* Validate 'err' */
return;
}
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*err = OS_ERR_PEVENT_NULL;
return;
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */
*err = OS_ERR_EVENT_TYPE;
return;
}
if (OSIntNesting > 0) { /* See if called from ISR ... */
*err = OS_ERR_PEND_ISR; /* ... can't PEND from an ISR */
return;
}
if (OSLockNesting > 0) { /* See if called with scheduler locked ... */
*err = OS_ERR_PEND_LOCKED; /* ... can't PEND when locked */
return;
}
OS_ENTER_CRITICAL();
pip = (INT8U)(pevent->OSEventCnt >> 8); /* Get PIP from mutex */
/* Is Mutex available? */
if ((INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8) == OS_MUTEX_AVAILABLE) {
pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8; /* Yes, Acquire the resource */
pevent->OSEventCnt |= OSTCBCur->OSTCBPrio; /* Save priority of owning task */
pevent->OSEventPtr = (void *)OSTCBCur; /* Point to owning task's OS_TCB */
if (OSTCBCur->OSTCBPrio <= pip) { /* PIP 'must' have a SMALLER prio ... */
OS_EXIT_CRITICAL(); /* ... than current task! */
*err = OS_ERR_PIP_LOWER;
} else {
OS_EXIT_CRITICAL();
*err = OS_NO_ERR;
}
return;
}
mprio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8); /* No, Get priority of mutex owner */
ptcb = (OS_TCB *)(pevent->OSEventPtr); /* Point to TCB of mutex owner */
if (ptcb->OSTCBPrio > pip) { /* Need to promote prio of owner?*/
if (mprio > OSTCBCur->OSTCBPrio) {
y = ptcb->OSTCBY;
if ((OSRdyTbl[y] & ptcb->OSTCBBitX) != 0) { /* See if mutex owner is ready */
OSRdyTbl[y] &= ~ptcb->OSTCBBitX; /* Yes, Remove owner from Rdy ...*/
if (OSRdyTbl[y] == 0) { /* ... list at current prio */
OSRdyGrp &= ~ptcb->OSTCBBitY;
}
rdy = OS_TRUE;
} else {
pevent2 = ptcb->OSTCBEventPtr;
if (pevent2 != (OS_EVENT *)0) { /* Remove from event wait list */
if ((pevent2->OSEventTbl[ptcb->OSTCBY] &= ~ptcb->OSTCBBitX) == 0) {
pevent2->OSEventGrp &= ~ptcb->OSTCBBitY;
}
}
rdy = OS_FALSE; /* No */
}
ptcb->OSTCBPrio = pip; /* Change owner task prio to PIP */
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