/* ********************************************************************************************************* * uC/OS-II * The Real-Time Kernel * MUTUAL EXCLUSION SEMAPHORE MANAGEMENT * * (c) Copyright 1992-2013, Micrium, Weston, FL * All Rights Reserved * * File : OS_MUTEX.C * By : Jean J. Labrosse * Version : V2.92.11 * * LICENSING TERMS: * --------------- * uC/OS-II is provided in source form for FREE evaluation, for educational use or for peaceful research. * If you plan on using uC/OS-II in a commercial product you need to contact Micrium to properly license * its use in your product. We provide ALL the source code for your convenience and to help you experience * uC/OS-II. The fact that the source is provided does NOT mean that you can use it without paying a * licensing fee. ********************************************************************************************************* */ #define MICRIUM_SOURCE #ifndef OS_MASTER_FILE #include #endif #if OS_MUTEX_EN > 0u /* ********************************************************************************************************* * LOCAL CONSTANTS ********************************************************************************************************* */ #define OS_MUTEX_KEEP_LOWER_8 ((INT16U)0x00FFu) #define OS_MUTEX_KEEP_UPPER_8 ((INT16U)0xFF00u) #define OS_MUTEX_AVAILABLE ((INT16U)0x00FFu) /* ********************************************************************************************************* * LOCAL CONSTANTS ********************************************************************************************************* */ static void OSMutex_RdyAtPrio(OS_TCB *ptcb, INT8U prio); /*$PAGE*/ /* ********************************************************************************************************* * ACCEPT MUTUAL EXCLUSION SEMAPHORE * * Description: This function checks the mutual exclusion semaphore to see if a resource is available. * Unlike OSMutexPend(), OSMutexAccept() does not suspend the calling task if the resource is * not available or the event did not occur. * * Arguments : pevent is a pointer to the event control block * * perr is a pointer to an error code which will be returned to your application: * OS_ERR_NONE if the call was successful. * OS_ERR_EVENT_TYPE if 'pevent' is not 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 * OS_ERR_PCP_LOWER If the priority of the task that owns the Mutex is * HIGHER (i.e. a lower number) than the PCP. This error * indicates that you did not set the PCP 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 : == OS_TRUE if the resource is available, the mutual exclusion semaphore is acquired * == OS_FALSE a) if the resource is not available * b) you didn't pass a pointer to a mutual exclusion semaphore * c) you called this function from an ISR * * Warning(s) : This function CANNOT be called from an ISR because mutual exclusion semaphores are * intended to be used by tasks only. ********************************************************************************************************* */ #if OS_MUTEX_ACCEPT_EN > 0u BOOLEAN OSMutexAccept (OS_EVENT *pevent, INT8U *perr) { INT8U pcp; /* Priority Ceiling Priority (PCP) */ #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return (OS_FALSE); } #endif #if OS_ARG_CHK_EN > 0u if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */ *perr = OS_ERR_PEVENT_NULL; return (OS_FALSE); } #endif if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */ *perr = OS_ERR_EVENT_TYPE; return (OS_FALSE); } if (OSIntNesting > 0u) { /* Make sure it's not called from an ISR */ *perr = OS_ERR_PEND_ISR; return (OS_FALSE); } OS_ENTER_CRITICAL(); /* Get value (0 or 1) of Mutex */ pcp = (INT8U)(pevent->OSEventCnt >> 8u); /* Get PCP from mutex */ if ((pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8) == OS_MUTEX_AVAILABLE) { pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8; /* Mask off LSByte (Acquire Mutex) */ pevent->OSEventCnt |= OSTCBCur->OSTCBPrio; /* Save current task priority in LSByte */ pevent->OSEventPtr = (void *)OSTCBCur; /* Link TCB of task owning Mutex */ if ((pcp != OS_PRIO_MUTEX_CEIL_DIS) && (OSTCBCur->OSTCBPrio <= pcp)) { /* PCP 'must' have a SMALLER prio ... */ OS_EXIT_CRITICAL(); /* ... than current task! */ *perr = OS_ERR_PCP_LOWER; } else { OS_EXIT_CRITICAL(); *perr = OS_ERR_NONE; } return (OS_TRUE); } OS_EXIT_CRITICAL(); *perr = OS_ERR_NONE; return (OS_FALSE); } #endif /*$PAGE*/ /* ********************************************************************************************************* * CREATE A MUTUAL EXCLUSION SEMAPHORE * * Description: This function creates a mutual exclusion semaphore. * * Arguments : prio is the priority to use when accessing the mutual exclusion semaphore. In * other words, when the semaphore is acquired and a higher priority task * attempts to obtain the semaphore then the priority of the task owning the * semaphore is raised to this priority. It is assumed that you will specify * a priority that is LOWER in value than ANY of the tasks competing for the * mutex. If the priority is specified as OS_PRIO_MUTEX_CEIL_DIS, then the * priority ceiling promotion is disabled. This way, the tasks accessing the * semaphore do not have their priority promoted. * * perr is a pointer to an error code which will be returned to your application: * OS_ERR_NONE if the call was successful. * OS_ERR_CREATE_ISR if you attempted to create a MUTEX from an ISR * OS_ERR_PRIO_EXIST if a task at the priority ceiling priority * already exist. * OS_ERR_PEVENT_NULL No more event control blocks available. * OS_ERR_PRIO_INVALID if the priority you specify is higher that the * maximum allowed (i.e. > OS_LOWEST_PRIO) * * Returns : != (void *)0 is a pointer to the event control clock (OS_EVENT) associated with the * created mutex. * == (void *)0 if an error is detected. * * Note(s) : 1) The LEAST significant 8 bits of '.OSEventCnt' hold the priority number of the task * owning the mutex or 0xFF if no task owns the mutex. * * 2) The MOST significant 8 bits of '.OSEventCnt' hold the priority number used to * reduce priority inversion or 0xFF (OS_PRIO_MUTEX_CEIL_DIS) if priority ceiling * promotion is disabled. ********************************************************************************************************* */ OS_EVENT *OSMutexCreate (INT8U prio, INT8U *perr) { OS_EVENT *pevent; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return ((OS_EVENT *)0); } #endif #ifdef OS_SAFETY_CRITICAL_IEC61508 if (OSSafetyCriticalStartFlag == OS_TRUE) { OS_SAFETY_CRITICAL_EXCEPTION(); return ((OS_EVENT *)0); } #endif #if OS_ARG_CHK_EN > 0u if (prio != OS_PRIO_MUTEX_CEIL_DIS) { if (prio >= OS_LOWEST_PRIO) { /* Validate PCP */ *perr = OS_ERR_PRIO_INVALID; return ((OS_EVENT *)0); } } #endif if (OSIntNesting > 0u) { /* See if called from ISR ... */ *perr = OS_ERR_CREATE_ISR; /* ... can't CREATE mutex from an ISR */ return ((OS_EVENT *)0); } OS_ENTER_CRITICAL(); if (prio != OS_PRIO_MUTEX_CEIL_DIS) { if (OSTCBPrioTbl[prio] != (OS_TCB *)0) { /* Mutex priority must not already exist */ OS_EXIT_CRITICAL(); /* Task already exist at priority ... */ *perr = OS_ERR_PRIO_EXIST; /* ... ceiling priority */ return ((OS_EVENT *)0); } OSTCBPrioTbl[prio] = OS_TCB_RESERVED; /* Reserve the table entry */ } pevent = OSEventFreeList; /* Get next free event control block */ if (pevent == (OS_EVENT *)0) { /* See if an ECB was available */ if (prio != OS_PRIO_MUTEX_CEIL_DIS) { OSTCBPrioTbl[prio] = (OS_TCB *)0; /* No, Release the table entry */ } OS_EXIT_CRITICAL(); *perr = OS_ERR_PEVENT_NULL; /* No more event control blocks */ return (pevent); } OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr; /* Adjust the free list */ OS_EXIT_CRITICAL(); pevent->OSEventType = OS_EVENT_TYPE_MUTEX; pevent->OSEventCnt = (INT16U)((INT16U)prio << 8u) | OS_MUTEX_AVAILABLE; /* Resource is avail. */ pevent->OSEventPtr = (void *)0; /* No task owning the mutex */ #if OS_EVENT_NAME_EN > 0u pevent->OSEventName = (INT8U *)(void *)"?"; #endif OS_EventWaitListInit(pevent); *perr = OS_ERR_NONE; return (pevent); } /*$PAGE*/ /* ********************************************************************************************************* * DELETE A MUTEX * * Description: This function deletes a mutual exclusion semaphore and readies all tasks pending on the it. * * Arguments : pevent is a pointer to the event control block associated with the desired mutex. * * opt determines delete options as follows: * opt == OS_DEL_NO_PEND Delete mutex ONLY if no task pending * opt == OS_DEL_ALWAYS Deletes the mutex even if tasks are waiting. * In this case, all the tasks pending will be readied. * * perr is a pointer to an error code that can contain one of the following values: * OS_ERR_NONE The call was successful and the mutex was deleted * OS_ERR_DEL_ISR If you attempted to delete the MUTEX from an ISR * OS_ERR_INVALID_OPT An invalid option was specified * OS_ERR_TASK_WAITING One or more tasks were waiting on the mutex * OS_ERR_EVENT_TYPE If you didn't pass a pointer to a mutex * OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer. * * Returns : pevent upon error * (OS_EVENT *)0 if the mutex was successfully deleted. * * Note(s) : 1) This function must be used with care. Tasks that would normally expect the presence of * the mutex MUST check the return code of OSMutexPend(). * * 2) This call can potentially disable interrupts for a long time. The interrupt disable * 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 > 0u OS_EVENT *OSMutexDel (OS_EVENT *pevent, INT8U opt, INT8U *perr) { BOOLEAN tasks_waiting; OS_EVENT *pevent_return; INT8U pcp; /* Priority ceiling priority */ INT8U prio; OS_TCB *ptcb; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return ((OS_EVENT *)0); } #endif #if OS_ARG_CHK_EN > 0u if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */ *perr = OS_ERR_PEVENT_NULL; return (pevent); } #endif if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */ *perr = OS_ERR_EVENT_TYPE; return (pevent); } if (OSIntNesting > 0u) { /* See if called from ISR ... */ *perr = OS_ERR_DEL_ISR; /* ... can't DELETE from an ISR */ return (pevent); } OS_ENTER_CRITICAL(); if (pevent->OSEventGrp != 0u) { /* 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_EN > 0u pevent->OSEventName = (INT8U *)(void *)"?"; #endif pcp = (INT8U)(pevent->OSEventCnt >> 8u); if (pcp != OS_PRIO_MUTEX_CEIL_DIS) { OSTCBPrioTbl[pcp] = (OS_TCB *)0; /* Free up the PCP */ } pevent->OSEventType = OS_EVENT_TYPE_UNUSED; pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */ pevent->OSEventCnt = 0u; OSEventFreeList = pevent; OS_EXIT_CRITICAL(); *perr = OS_ERR_NONE; pevent_return = (OS_EVENT *)0; /* Mutex has been deleted */ } else { OS_EXIT_CRITICAL(); *perr = OS_ERR_TASK_WAITING; pevent_return = pevent; } break; case OS_DEL_ALWAYS: /* ALWAYS DELETE THE MUTEX ---------------- */ pcp = (INT8U)(pevent->OSEventCnt >> 8u); /* Get PCP of mutex */ if (pcp != OS_PRIO_MUTEX_CEIL_DIS) { prio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8); /* Get owner's orig prio */ ptcb = (OS_TCB *)pevent->OSEventPtr; if (ptcb != (OS_TCB *)0) { /* See if any task owns the mutex */ if (ptcb->OSTCBPrio == pcp) { /* See if original prio was changed */ OSMutex_RdyAtPrio(ptcb, prio); /* Yes, Restore the task's original prio */ } } } while (pevent->OSEventGrp != 0u) { /* Ready ALL tasks waiting for mutex */ (void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MUTEX, OS_STAT_PEND_ABORT); } #if OS_EVENT_NAME_EN > 0u pevent->OSEventName = (INT8U *)(void *)"?"; #endif pcp = (INT8U)(pevent->OSEventCnt >> 8u); if (pcp != OS_PRIO_MUTEX_CEIL_DIS) { OSTCBPrioTbl[pcp] = (OS_TCB *)0; /* Free up the PCP */ } pevent->OSEventType = OS_EVENT_TYPE_UNUSED; pevent->OSEventPtr = OSEventFreeList; /* Return Event Control Block to free list */ pevent->OSEventCnt = 0u; 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 */ } *perr = OS_ERR_NONE; pevent_return = (OS_EVENT *)0; /* Mutex has been deleted */ break; default: OS_EXIT_CRITICAL(); *perr = 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. * * perr is a pointer to where an error message will be deposited. Possible error * messages are: * OS_ERR_NONE The call was successful and your task owns the mutex * OS_ERR_TIMEOUT The mutex was not available within the specified 'timeout'. * OS_ERR_PEND_ABORT The wait on the mutex was aborted. * 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_PCP_LOWER If the priority of the task that owns the Mutex is * HIGHER (i.e. a lower number) than the PCP. This error * indicates that you did not set the PCP 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. * OS_ERR_PEND_LOCKED If you called this function when the scheduler is locked * * 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, INT32U timeout, INT8U *perr) { INT8U pcp; /* Priority Ceiling Priority (PCP) */ INT8U mprio; /* Mutex owner priority */ BOOLEAN rdy; /* Flag indicating task was ready */ OS_TCB *ptcb; OS_EVENT *pevent2; INT8U y; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif #ifdef OS_SAFETY_CRITICAL if (perr == (INT8U *)0) { OS_SAFETY_CRITICAL_EXCEPTION(); return; } #endif #if OS_ARG_CHK_EN > 0u if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */ *perr = OS_ERR_PEVENT_NULL; return; } #endif if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */ *perr = OS_ERR_EVENT_TYPE; return; } if (OSIntNesting > 0u) { /* See if called from ISR ... */ *perr = OS_ERR_PEND_ISR; /* ... can't PEND from an ISR */ return; } if (OSLockNesting > 0u) { /* See if called with scheduler locked ... */ *perr = OS_ERR_PEND_LOCKED; /* ... can't PEND when locked */ return; } /*$PAGE*/ OS_ENTER_CRITICAL(); pcp = (INT8U)(pevent->OSEventCnt >> 8u); /* Get PCP 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 ((pcp != OS_PRIO_MUTEX_CEIL_DIS) && (OSTCBCur->OSTCBPrio <= pcp)) { /* PCP 'must' have a SMALLER prio ... */ OS_EXIT_CRITICAL(); /* ... than current task! */ *perr = OS_ERR_PCP_LOWER; } else { OS_EXIT_CRITICAL(); *perr = OS_ERR_NONE; } return; } if (pcp != OS_PRIO_MUTEX_CEIL_DIS) { mprio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8); /* Get priority of mutex owner */ ptcb = (OS_TCB *)(pevent->OSEventPtr); /* Point to TCB of mutex owner */ if (ptcb->OSTCBPrio > pcp) { /* Need to promote prio of owner?*/ if (mprio > OSTCBCur->OSTCBPrio) { y = ptcb->OSTCBY; if ((OSRdyTbl[y] & ptcb->OSTCBBitX) != 0u) { /* See if mutex owner is ready */ OSRdyTbl[y] &= (OS_PRIO)~ptcb->OSTCBBitX; /* Yes, Remove owner from Rdy ...*/ if (OSRdyTbl[y] == 0u) { /* ... list at current prio */ OSRdyGrp &= (OS_PRIO)~ptcb->OSTCBBitY; } rdy = OS_TRUE; } else { pevent2 = ptcb->OSTCBEventPtr; if (pevent2 != (OS_EVENT *)0) { /* Remove from event wait list */ y = ptcb->OSTCBY; pevent2->OSEventTbl[y] &= (OS_PRIO)~ptcb->OSTCBBitX; if (pevent2->OSEventTbl[y] == 0u) { pevent2->OSEventGrp &= (OS_PRIO)~ptcb->OSTCBBitY; } } rdy = OS_FALSE; /* No */ } ptcb->OSTCBPrio = pcp; /* Change owner task prio to PCP */ #if OS_LOWEST_PRIO <= 63u ptcb->OSTCBY = (INT8U)( ptcb->OSTCBPrio >> 3u); ptcb->OSTCBX = (INT8U)( ptcb->OSTCBPrio & 0x07u); #else ptcb->OSTCBY = (INT8U)((INT8U)(ptcb->OSTCBPrio >> 4u) & 0xFFu); ptcb->OSTCBX = (INT8U)( ptcb->OSTCBPrio & 0x0Fu); #endif ptcb->OSTCBBitY = (OS_PRIO)(1uL << ptcb->OSTCBY); ptcb->OSTCBBitX = (OS_PRIO)(1uL << ptcb->OSTCBX); if (rdy == OS_TRUE) { /* If task was ready at owner's priority ...*/ OSRdyGrp |= ptcb->OSTCBBitY; /* ... make it ready at new priority. */ OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX; } else { pevent2 = ptcb->OSTCBEventPtr; if (pevent2 != (OS_EVENT *)0) { /* Add to event wait list */ pevent2->OSEventGrp |= ptcb->OSTCBBitY; pevent2->OSEventTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX; } } OSTCBPrioTbl[pcp] = ptcb; } } } OSTCBCur->OSTCBStat |= OS_STAT_MUTEX; /* Mutex not available, pend current task */ OSTCBCur->OSTCBStatPend = OS_STAT_PEND_OK; OSTCBCur->OSTCBDly = timeout; /* Store timeout in current task's TCB */ OS_EventTaskWait(pevent); /* Suspend task until event or timeout occurs */ OS_EXIT_CRITICAL(); OS_Sched(); /* Find next highest priority task ready */ OS_ENTER_CRITICAL(); switch (OSTCBCur->OSTCBStatPend) { /* See if we timed-out or aborted */ case OS_STAT_PEND_OK: *perr = OS_ERR_NONE; break; case OS_STAT_PEND_ABORT: *perr = OS_ERR_PEND_ABORT; /* Indicate that we aborted getting mutex */ break; case OS_STAT_PEND_TO: default: OS_EventTaskRemove(OSTCBCur, pevent); *perr = OS_ERR_TIMEOUT; /* Indicate that we didn't get mutex within TO */ break; } OSTCBCur->OSTCBStat = OS_STAT_RDY; /* Set task status to ready */ OSTCBCur->OSTCBStatPend = OS_STAT_PEND_OK; /* Clear pend status */ OSTCBCur->OSTCBEventPtr = (OS_EVENT *)0; /* Clear event pointers */ #if (OS_EVENT_MULTI_EN > 0u) OSTCBCur->OSTCBEventMultiPtr = (OS_EVENT **)0; #endif OS_EXIT_CRITICAL(); } /*$PAGE*/ /* ********************************************************************************************************* * POST TO A MUTUAL EXCLUSION SEMAPHORE * * Description: This function signals a mutual exclusion semaphore * * Arguments : pevent is a pointer to the event control block associated with the desired * mutex. * * Returns : OS_ERR_NONE The call was successful and the mutex was signaled. * 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_POST_ISR Attempted to post from an ISR (not valid for MUTEXes) * OS_ERR_NOT_MUTEX_OWNER The task that did the post is NOT the owner of the MUTEX. * OS_ERR_PCP_LOWER If the priority of the new task that owns the Mutex is * HIGHER (i.e. a lower number) than the PCP. This error * indicates that you did not set the PCP 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. ********************************************************************************************************* */ INT8U OSMutexPost (OS_EVENT *pevent) { INT8U pcp; /* Priority ceiling priority */ INT8U prio; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif if (OSIntNesting > 0u) { /* See if called from ISR ... */ return (OS_ERR_POST_ISR); /* ... can't POST mutex from an ISR */ } #if OS_ARG_CHK_EN > 0u if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */ return (OS_ERR_PEVENT_NULL); } #endif if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */ return (OS_ERR_EVENT_TYPE); } OS_ENTER_CRITICAL(); pcp = (INT8U)(pevent->OSEventCnt >> 8u); /* Get priority ceiling priority of mutex */ prio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8); /* Get owner's original priority */ if (OSTCBCur != (OS_TCB *)pevent->OSEventPtr) { /* See if posting task owns the MUTEX */ OS_EXIT_CRITICAL(); return (OS_ERR_NOT_MUTEX_OWNER); } if (pcp != OS_PRIO_MUTEX_CEIL_DIS) { if (OSTCBCur->OSTCBPrio == pcp) { /* Did we have to raise current task's priority? */ OSMutex_RdyAtPrio(OSTCBCur, prio); /* Restore the task's original priority */ } OSTCBPrioTbl[pcp] = OS_TCB_RESERVED; /* Reserve table entry */ } if (pevent->OSEventGrp != 0u) { /* Any task waiting for the mutex? */ /* Yes, Make HPT waiting for mutex ready */ prio = OS_EventTaskRdy(pevent, (void *)0, OS_STAT_MUTEX, OS_STAT_PEND_OK); pevent->OSEventCnt &= OS_MUTEX_KEEP_UPPER_8; /* Save priority of mutex's new owner */ pevent->OSEventCnt |= prio; pevent->OSEventPtr = OSTCBPrioTbl[prio]; /* Link to new mutex owner's OS_TCB */ if ((pcp != OS_PRIO_MUTEX_CEIL_DIS) && (prio <= pcp)) { /* PCP 'must' have a SMALLER prio ... */ OS_EXIT_CRITICAL(); /* ... than current task! */ OS_Sched(); /* Find highest priority task ready to run */ return (OS_ERR_PCP_LOWER); } else { OS_EXIT_CRITICAL(); OS_Sched(); /* Find highest priority task ready to run */ return (OS_ERR_NONE); } } pevent->OSEventCnt |= OS_MUTEX_AVAILABLE; /* No, Mutex is now available */ pevent->OSEventPtr = (void *)0; OS_EXIT_CRITICAL(); return (OS_ERR_NONE); } /*$PAGE*/ /* ********************************************************************************************************* * QUERY A MUTUAL EXCLUSION SEMAPHORE * * Description: This function obtains information about a mutex * * Arguments : pevent is a pointer to the event control block associated with the desired mutex * * p_mutex_data is a pointer to a structure that will contain information about the mutex * * Returns : OS_ERR_NONE The call was successful and the message was sent * OS_ERR_QUERY_ISR If you called this function from an ISR * OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer * OS_ERR_PDATA_NULL If 'p_mutex_data' is a NULL pointer * OS_ERR_EVENT_TYPE If you are attempting to obtain data from a non mutex. ********************************************************************************************************* */ #if OS_MUTEX_QUERY_EN > 0u INT8U OSMutexQuery (OS_EVENT *pevent, OS_MUTEX_DATA *p_mutex_data) { INT8U i; OS_PRIO *psrc; OS_PRIO *pdest; #if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */ OS_CPU_SR cpu_sr = 0u; #endif if (OSIntNesting > 0u) { /* See if called from ISR ... */ return (OS_ERR_QUERY_ISR); /* ... can't QUERY mutex from an ISR */ } #if OS_ARG_CHK_EN > 0u if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */ return (OS_ERR_PEVENT_NULL); } if (p_mutex_data == (OS_MUTEX_DATA *)0) { /* Validate 'p_mutex_data' */ return (OS_ERR_PDATA_NULL); } #endif if (pevent->OSEventType != OS_EVENT_TYPE_MUTEX) { /* Validate event block type */ return (OS_ERR_EVENT_TYPE); } OS_ENTER_CRITICAL(); p_mutex_data->OSMutexPCP = (INT8U)(pevent->OSEventCnt >> 8u); p_mutex_data->OSOwnerPrio = (INT8U)(pevent->OSEventCnt & OS_MUTEX_KEEP_LOWER_8); if (p_mutex_data->OSOwnerPrio == 0xFFu) { p_mutex_data->OSValue = OS_TRUE; } else { p_mutex_data->OSValue = OS_FALSE; } p_mutex_data->OSEventGrp = pevent->OSEventGrp; /* Copy wait list */ psrc = &pevent->OSEventTbl[0]; pdest = &p_mutex_data->OSEventTbl[0]; for (i = 0u; i < OS_EVENT_TBL_SIZE; i++) { *pdest++ = *psrc++; } OS_EXIT_CRITICAL(); return (OS_ERR_NONE); } #endif /* OS_MUTEX_QUERY_EN */ /*$PAGE*/ /* ********************************************************************************************************* * RESTORE A TASK BACK TO ITS ORIGINAL PRIORITY * * Description: This function makes a task ready at the specified priority * * Arguments : ptcb is a pointer to OS_TCB of the task to make ready * * prio is the desired priority * * Returns : none ********************************************************************************************************* */ static void OSMutex_RdyAtPrio (OS_TCB *ptcb, INT8U prio) { INT8U y; y = ptcb->OSTCBY; /* Remove owner from ready list at 'pcp' */ OSRdyTbl[y] &= (OS_PRIO)~ptcb->OSTCBBitX; if (OSRdyTbl[y] == 0u) { OSRdyGrp &= (OS_PRIO)~ptcb->OSTCBBitY; } ptcb->OSTCBPrio = prio; OSPrioCur = prio; /* The current task is now at this priority */ #if OS_LOWEST_PRIO <= 63u ptcb->OSTCBY = (INT8U)((INT8U)(prio >> 3u) & 0x07u); ptcb->OSTCBX = (INT8U)(prio & 0x07u); #else ptcb->OSTCBY = (INT8U)((INT8U)(prio >> 4u) & 0x0Fu); ptcb->OSTCBX = (INT8U) (prio & 0x0Fu); #endif ptcb->OSTCBBitY = (OS_PRIO)(1uL << ptcb->OSTCBY); ptcb->OSTCBBitX = (OS_PRIO)(1uL << ptcb->OSTCBX); OSRdyGrp |= ptcb->OSTCBBitY; /* Make task ready at original priority */ OSRdyTbl[ptcb->OSTCBY] |= ptcb->OSTCBBitX; OSTCBPrioTbl[prio] = ptcb; } #endif /* OS_MUTEX_EN */