> 上文主要介绍了信号量相关的函数，本文介绍消息队列相关的函数：OSQCreate()建立消息队列函数,OSQPend()任务等待消息函数,其他的消息函数.
## 消息队列介绍
消息队列是µC/OS-II中另一种通讯机制，它可以使一个任务或者中断服务子程序向另一个任务发送以指针方式定义的变量。因具体的应用有所不同，每个指针指向的数据结构变量也有所不同。为了使用µC/OS-II的消息队列功能，需要在OS_CFG.H 文件中，将OS_Q_EN常数设置为1，并且通过常数OS_MAX_QS来决定µC/OS-II支持的最多消息队列数。
## OSQCreate()建立消息队列函数
1、主要作用：该函数用于建立一个消息队列。任务或中断可以通过消息队列向一个或多个任务发送消息。消息的含义是和具体的应用密切相关的。
2、函数原型：OS_EVENT *OSQCreate (void **start, INT8U size);
3、参数说明：start 是消息内存区的首地址，消息内存区是一个指针数组
size 是消息内存区的大小。
4、返回值说明：OSQCreate() 函数返回一个指向消息队列控制块的指针。如果没有空闲的控制块，OSQCreate() 函数返回空指针
5、函数主体在os_q.c中
## OSQPend()任务等待消息函数
1、主要作用： 该函数用于任务等待消息。消息通过中断或任务发送给需要的任务。消息是一个指针变量，在不同的应用中消息的具体含义不同。如果调用 OSQPend() 函数时队列中已经存在消息，那么该消息被返回给 OSQPend() 函数的调用者，该消息同时从队列中清除。如果调用 OSQPend() 函数时队列中没有消息，OSQPend() 函数挂起调用任务直到得到消息或超出定义的超时时间。如果同时有多个任务等待同一个消息，μC/OS-Ⅱ默认最高优先级的任务取得消息。一个由 OSTaskSuspend() 函数挂起的任务也可以接受消息，但这个任务将一直保持挂起状态直到通过调用 OSTaskResume() 函数恢复任务的运行。
2、函数原型：void *OSQPend (OS_EVENT *pevent, INT16U timeout, INT8U *err);
3、参数说明：pevent 是指向消息队列的指针，该指针的值在建立该队列时可以得到。（参考 OSQCreate() 函数）。 timeout 允许一个任务以指定数目的时钟节拍等待消息。超时后如果还没有得到消息则恢复成就绪状态。如果该值设置成零则表示任务将持续地等待消息，最大的等待时间为65535个时钟节拍。这个时间长度并不是非常严格的，可能存在一个时钟节拍的误差。
err 是指向包含错误码的变量的指针。OSQPend() 函数返回的错误码可能为下述几种：
* OS_NO_ERR ：消息被正确地接受。
* OS_TIMEOUT ：消息没有在指定的时钟周期数内接收到消息。
* OS_ERR_PEND_ISR ：从中断调用该函数。虽然规定了不允许从中断中调用该函数，但μC/OS-Ⅱ仍然包含了检测这种情况的功能。
* OS_ERR_EVENT_TYPE ：pevent 不是指向消息队列的指针。
4、返回值说明：OSQPend() 函数返回取得的消息并将 *err 置为 OS_NO_ERR。如果没有在指定数目的时钟节拍内接受到消息，OSQPend() 函数返回空指针并将 *err 设置为 OS_TIMEOUT。
5、函数主体在os_q.c中
## 其他的消息函数
INT8U OSQPost (OS_EVENT *pevent, void *msg)
发送一个消息到消息队列 FIFO模式
INT8U OSQPostFront (OS_EVENT *pevent, void *msg)
发送一个消息到消息队列 FIFO模式
void *OSQAccept (OS_EVENT *pevent)
无等待地从消息队列中得到一个消息
INT8U OSQFlush (OS_EVENT *pevent)
清空一个消息队列
INT8U OSQQuery (OS_EVENT *pevent, OS_Q_DATA *pdata)
查询一个消息队列的当前状态
使用消息队列的通常步骤为：
1）定义指针： OS_EVENT *proSQ
定义指针数组： void *start[4]
2) 在主程序中建立信号列队：*proSQ = OSQCreate(start,4);
3）在任务中等待消息列队中得到消息或者给消息列队发送消息
## 附os_q.c代码
~~~
/**********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
* MESSAGE QUEUE MANAGEMENT
*
* (c) Copyright 1992-2013, Micrium, Weston, FL
* All Rights Reserved
*
* File : OS_Q.C
* By : Jean J. Labrosse
* Version : V2.92.08
*
* 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 <ucos_ii.h>
#endif
#if (OS_Q_EN > 0u) && (OS_MAX_QS > 0u)
/*
*********************************************************************************************************
* ACCEPT MESSAGE FROM QUEUE
*
* Description: This function checks the queue to see if a message is available. Unlike OSQPend(),
* OSQAccept() does not suspend the calling task if a message is not available.
*
* Arguments : pevent is a pointer to the event control block
*
* 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 received a
* message.
* OS_ERR_EVENT_TYPE You didn't pass a pointer to a queue
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
* OS_ERR_Q_EMPTY The queue did not contain any messages
*
* Returns : != (void *)0 is the message in the queue if one is available. The message is removed
* from the so the next time OSQAccept() is called, the queue will contain
* one less entry.
* == (void *)0 if you received a NULL pointer message
* if the queue is empty or,
* if 'pevent' is a NULL pointer or,
* if you passed an invalid event type
*
* Note(s) : As of V2.60, you can now pass NULL pointers through queues. Because of this, the argument
* 'perr' has been added to the API to tell you about the outcome of the call.
*********************************************************************************************************
*/
#if OS_Q_ACCEPT_EN > 0u
void *OSQAccept (OS_EVENT *pevent,
INT8U *perr)
{
void *pmsg;
OS_Q *pq;
#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 ((void *)0);
}
#endif
#if OS_ARG_CHK_EN > 0u
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*perr = OS_ERR_PEVENT_NULL;
return ((void *)0);
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_Q) {/* Validate event block type */
*perr = OS_ERR_EVENT_TYPE;
return ((void *)0);
}
OS_ENTER_CRITICAL();
pq = (OS_Q *)pevent->OSEventPtr; /* Point at queue control block */
if (pq->OSQEntries > 0u) { /* See if any messages in the queue */
pmsg = *pq->OSQOut++; /* Yes, extract oldest message from the queue */
pq->OSQEntries--; /* Update the number of entries in the queue */
if (pq->OSQOut == pq->OSQEnd) { /* Wrap OUT pointer if we are at the end of the queue */
pq->OSQOut = pq->OSQStart;
}
*perr = OS_ERR_NONE;
} else {
*perr = OS_ERR_Q_EMPTY;
pmsg = (void *)0; /* Queue is empty */
}
OS_EXIT_CRITICAL();
return (pmsg); /* Return message received (or NULL) */
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* CREATE A MESSAGE QUEUE
*
* Description: This function creates a message queue if free event control blocks are available.
*
* Arguments : start is a pointer to the base address of the message queue storage area. The
* storage area MUST be declared as an array of pointers to 'void' as follows
*
* void *MessageStorage[size]
*
* size is the number of elements in the storage area
*
* Returns : != (OS_EVENT *)0 is a pointer to the event control clock (OS_EVENT) associated with the
* created queue
* == (OS_EVENT *)0 if no event control blocks were available or an error was detected
*********************************************************************************************************
*/
OS_EVENT *OSQCreate (void **start,
INT16U size)
{
OS_EVENT *pevent;
OS_Q *pq;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#ifdef OS_SAFETY_CRITICAL_IEC61508
if (OSSafetyCriticalStartFlag == OS_TRUE) {
OS_SAFETY_CRITICAL_EXCEPTION();
return ((OS_EVENT *)0);
}
#endif
if (OSIntNesting > 0u) { /* See if called from ISR ... */
return ((OS_EVENT *)0); /* ... can't CREATE from an ISR */
}
OS_ENTER_CRITICAL();
pevent = OSEventFreeList; /* Get next free event control block */
if (OSEventFreeList != (OS_EVENT *)0) { /* See if pool of free ECB pool was empty */
OSEventFreeList = (OS_EVENT *)OSEventFreeList->OSEventPtr;
}
OS_EXIT_CRITICAL();
if (pevent != (OS_EVENT *)0) { /* See if we have an event control block */
OS_ENTER_CRITICAL();
pq = OSQFreeList; /* Get a free queue control block */
if (pq != (OS_Q *)0) { /* Were we able to get a queue control block ? */
OSQFreeList = OSQFreeList->OSQPtr; /* Yes, Adjust free list pointer to next free*/
OS_EXIT_CRITICAL();
pq->OSQStart = start; /* Initialize the queue */
pq->OSQEnd = &start[size];
pq->OSQIn = start;
pq->OSQOut = start;
pq->OSQSize = size;
pq->OSQEntries = 0u;
pevent->OSEventType = OS_EVENT_TYPE_Q;
pevent->OSEventCnt = 0u;
pevent->OSEventPtr = pq;
#if OS_EVENT_NAME_EN > 0u
pevent->OSEventName = (INT8U *)(void *)"?";
#endif
OS_EventWaitListInit(pevent); /* Initialize the wait list */
} else {
pevent->OSEventPtr = (void *)OSEventFreeList; /* No, Return event control block on error */
OSEventFreeList = pevent;
OS_EXIT_CRITICAL();
pevent = (OS_EVENT *)0;
}
}
return (pevent);
}
/*$PAGE*/
/*
*********************************************************************************************************
* DELETE A MESSAGE QUEUE
*
* Description: This function deletes a message queue and readies all tasks pending on the queue.
*
* Arguments : pevent is a pointer to the event control block associated with the desired
* queue.
*
* opt determines delete options as follows:
* opt == OS_DEL_NO_PEND Delete the queue ONLY if no task pending
* opt == OS_DEL_ALWAYS Deletes the queue 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 queue was deleted
* OS_ERR_DEL_ISR If you tried to delete the queue from an ISR
* OS_ERR_INVALID_OPT An invalid option was specified
* OS_ERR_TASK_WAITING One or more tasks were waiting on the queue
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer.
*
* Returns : pevent upon error
* (OS_EVENT *)0 if the queue was successfully deleted.
*
* Note(s) : 1) This function must be used with care. Tasks that would normally expect the presence of
* the queue MUST check the return code of OSQPend().
* 2) OSQAccept() callers will not know that the intended queue has been deleted unless
* they check 'pevent' to see that it's a NULL pointer.
* 3) 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 queue.
* 4) Because ALL tasks pending on the queue will be readied, you MUST be careful in
* applications where the queue is used for mutual exclusion because the resource(s)
* will no longer be guarded by the queue.
* 5) If the storage for the message queue was allocated dynamically (i.e. using a malloc()
* type call) then your application MUST release the memory storage by call the counterpart
* call of the dynamic allocation scheme used. If the queue storage was created statically
* then, the storage can be reused.
* 6) All tasks that were waiting for the queue will be readied and returned an
* OS_ERR_PEND_ABORT if OSQDel() was called with OS_DEL_ALWAYS
*********************************************************************************************************
*/
#if OS_Q_DEL_EN > 0u
OS_EVENT *OSQDel (OS_EVENT *pevent,
INT8U opt,
INT8U *perr)
{
BOOLEAN tasks_waiting;
OS_EVENT *pevent_return;
OS_Q *pq;
#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_Q) { /* 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 queue */
tasks_waiting = OS_TRUE; /* Yes */
} else {
tasks_waiting = OS_FALSE; /* No */
}
switch (opt) {
case OS_DEL_NO_PEND: /* Delete queue only if no task waiting */
if (tasks_waiting == OS_FALSE) {
#if OS_EVENT_NAME_EN > 0u
pevent->OSEventName = (INT8U *)(void *)"?";
#endif
pq = (OS_Q *)pevent->OSEventPtr; /* Return OS_Q to free list */
pq->OSQPtr = OSQFreeList;
OSQFreeList = pq;
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();
*perr = OS_ERR_NONE;
pevent_return = (OS_EVENT *)0; /* Queue has been deleted */
} else {
OS_EXIT_CRITICAL();
*perr = OS_ERR_TASK_WAITING;
pevent_return = pevent;
}
break;
case OS_DEL_ALWAYS: /* Always delete the queue */
while (pevent->OSEventGrp != 0u) { /* Ready ALL tasks waiting for queue */
(void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_Q, OS_STAT_PEND_ABORT);
}
#if OS_EVENT_NAME_EN > 0u
pevent->OSEventName = (INT8U *)(void *)"?";
#endif
pq = (OS_Q *)pevent->OSEventPtr; /* Return OS_Q to free list */
pq->OSQPtr = OSQFreeList;
OSQFreeList = pq;
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; /* Queue has been deleted */
break;
default:
OS_EXIT_CRITICAL();
*perr = OS_ERR_INVALID_OPT;
pevent_return = pevent;
break;
}
return (pevent_return);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* FLUSH QUEUE
*
* Description : This function is used to flush the contents of the message queue.
*
* Arguments : none
*
* Returns : OS_ERR_NONE upon success
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
*
* WARNING : You should use this function with great care because, when to flush the queue, you LOOSE
* the references to what the queue entries are pointing to and thus, you could cause
* 'memory leaks'. In other words, the data you are pointing to that's being referenced
* by the queue entries should, most likely, need to be de-allocated (i.e. freed).
*********************************************************************************************************
*/
#if OS_Q_FLUSH_EN > 0u
INT8U OSQFlush (OS_EVENT *pevent)
{
OS_Q *pq;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#if OS_ARG_CHK_EN > 0u
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return (OS_ERR_PEVENT_NULL);
}
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}
#endif
OS_ENTER_CRITICAL();
pq = (OS_Q *)pevent->OSEventPtr; /* Point to queue storage structure */
pq->OSQIn = pq->OSQStart;
pq->OSQOut = pq->OSQStart;
pq->OSQEntries = 0u;
OS_EXIT_CRITICAL();
return (OS_ERR_NONE);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* PEND ON A QUEUE FOR A MESSAGE
*
* Description: This function waits for a message to be sent to a queue
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue
*
* timeout is an optional timeout period (in clock ticks). If non-zero, your task will
* wait for a message to arrive at the queue up to the amount of time
* specified by this argument. If you specify 0, however, your task will wait
* forever at the specified queue or, until a message arrives.
*
* 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 received a
* message.
* OS_ERR_TIMEOUT A message was not received within the specified 'timeout'.
* OS_ERR_PEND_ABORT The wait on the queue was aborted.
* OS_ERR_EVENT_TYPE You didn't pass a pointer to a queue
* OS_ERR_PEVENT_NULL If '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_PEND_LOCKED If you called this function with the scheduler is locked
*
* Returns : != (void *)0 is a pointer to the message received
* == (void *)0 if you received a NULL pointer message or,
* if no message was received or,
* if 'pevent' is a NULL pointer or,
* if you didn't pass a pointer to a queue.
*
* Note(s) : As of V2.60, this function allows you to receive NULL pointer messages.
*********************************************************************************************************
*/
void *OSQPend (OS_EVENT *pevent,
INT32U timeout,
INT8U *perr)
{
void *pmsg;
OS_Q *pq;
#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 ((void *)0);
}
#endif
#if OS_ARG_CHK_EN > 0u
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*perr = OS_ERR_PEVENT_NULL;
return ((void *)0);
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_Q) {/* Validate event block type */
*perr = OS_ERR_EVENT_TYPE;
return ((void *)0);
}
if (OSIntNesting > 0u) { /* See if called from ISR ... */
*perr = OS_ERR_PEND_ISR; /* ... can't PEND from an ISR */
return ((void *)0);
}
if (OSLockNesting > 0u) { /* See if called with scheduler locked ... */
*perr = OS_ERR_PEND_LOCKED; /* ... can't PEND when locked */
return ((void *)0);
}
OS_ENTER_CRITICAL();
pq = (OS_Q *)pevent->OSEventPtr; /* Point at queue control block */
if (pq->OSQEntries > 0u) { /* See if any messages in the queue */
pmsg = *pq->OSQOut++; /* Yes, extract oldest message from the queue */
pq->OSQEntries--; /* Update the number of entries in the queue */
if (pq->OSQOut == pq->OSQEnd) { /* Wrap OUT pointer if we are at the end of the queue */
pq->OSQOut = pq->OSQStart;
}
OS_EXIT_CRITICAL();
*perr = OS_ERR_NONE;
return (pmsg); /* Return message received */
}
OSTCBCur->OSTCBStat |= OS_STAT_Q; /* Task will have to pend for a message to be posted */
OSTCBCur->OSTCBStatPend = OS_STAT_PEND_OK;
OSTCBCur->OSTCBDly = timeout; /* Load timeout into TCB */
OS_EventTaskWait(pevent); /* Suspend task until event or timeout occurs */
OS_EXIT_CRITICAL();
OS_Sched(); /* Find next highest priority task ready to run */
OS_ENTER_CRITICAL();
switch (OSTCBCur->OSTCBStatPend) { /* See if we timed-out or aborted */
case OS_STAT_PEND_OK: /* Extract message from TCB (Put there by QPost) */
pmsg = OSTCBCur->OSTCBMsg;
*perr = OS_ERR_NONE;
break;
case OS_STAT_PEND_ABORT:
pmsg = (void *)0;
*perr = OS_ERR_PEND_ABORT; /* Indicate that we aborted */
break;
case OS_STAT_PEND_TO:
default:
OS_EventTaskRemove(OSTCBCur, pevent);
pmsg = (void *)0;
*perr = OS_ERR_TIMEOUT; /* Indicate that we didn't get event 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
OSTCBCur->OSTCBMsg = (void *)0; /* Clear received message */
OS_EXIT_CRITICAL();
return (pmsg); /* Return received message */
}
/*$PAGE*/
/*
*********************************************************************************************************
* ABORT WAITING ON A MESSAGE QUEUE
*
* Description: This function aborts & readies any tasks currently waiting on a queue. This function
* should be used to fault-abort the wait on the queue, rather than to normally signal
* the queue via OSQPost(), OSQPostFront() or OSQPostOpt().
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue.
*
* opt determines the type of ABORT performed:
* OS_PEND_OPT_NONE ABORT wait for a single task (HPT) waiting on the
* queue
* OS_PEND_OPT_BROADCAST ABORT wait for ALL tasks that are waiting on the
* queue
*
* perr is a pointer to where an error message will be deposited. Possible error
* messages are:
*
* OS_ERR_NONE No tasks were waiting on the queue.
* OS_ERR_PEND_ABORT At least one task waiting on the queue was readied
* and informed of the aborted wait; check return value
* for the number of tasks whose wait on the queue
* was aborted.
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer.
*
* Returns : == 0 if no tasks were waiting on the queue, or upon error.
* > 0 if one or more tasks waiting on the queue are now readied and informed.
*********************************************************************************************************
*/
#if OS_Q_PEND_ABORT_EN > 0u
INT8U OSQPendAbort (OS_EVENT *pevent,
INT8U opt,
INT8U *perr)
{
INT8U nbr_tasks;
#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 (0u);
}
#endif
#if OS_ARG_CHK_EN > 0u
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
*perr = OS_ERR_PEVENT_NULL;
return (0u);
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
*perr = OS_ERR_EVENT_TYPE;
return (0u);
}
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0u) { /* See if any task waiting on queue? */
nbr_tasks = 0u;
switch (opt) {
case OS_PEND_OPT_BROADCAST: /* Do we need to abort ALL waiting tasks? */
while (pevent->OSEventGrp != 0u) { /* Yes, ready ALL tasks waiting on queue */
(void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_Q, OS_STAT_PEND_ABORT);
nbr_tasks++;
}
break;
case OS_PEND_OPT_NONE:
default: /* No, ready HPT waiting on queue */
(void)OS_EventTaskRdy(pevent, (void *)0, OS_STAT_Q, OS_STAT_PEND_ABORT);
nbr_tasks++;
break;
}
OS_EXIT_CRITICAL();
OS_Sched(); /* Find HPT ready to run */
*perr = OS_ERR_PEND_ABORT;
return (nbr_tasks);
}
OS_EXIT_CRITICAL();
*perr = OS_ERR_NONE;
return (0u); /* No tasks waiting on queue */
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* POST MESSAGE TO A QUEUE
*
* Description: This function sends a message to a queue
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue
*
* pmsg is a pointer to the message to send.
*
* Returns : OS_ERR_NONE The call was successful and the message was sent
* OS_ERR_Q_FULL If the queue cannot accept any more messages because it is full.
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
*
* Note(s) : As of V2.60, this function allows you to send NULL pointer messages.
*********************************************************************************************************
*/
#if OS_Q_POST_EN > 0u
INT8U OSQPost (OS_EVENT *pevent,
void *pmsg)
{
OS_Q *pq;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#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_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0u) { /* See if any task pending on queue */
/* Ready highest priority task waiting on event */
(void)OS_EventTaskRdy(pevent, pmsg, OS_STAT_Q, OS_STAT_PEND_OK);
OS_EXIT_CRITICAL();
OS_Sched(); /* Find highest priority task ready to run */
return (OS_ERR_NONE);
}
pq = (OS_Q *)pevent->OSEventPtr; /* Point to queue control block */
if (pq->OSQEntries >= pq->OSQSize) { /* Make sure queue is not full */
OS_EXIT_CRITICAL();
return (OS_ERR_Q_FULL);
}
*pq->OSQIn++ = pmsg; /* Insert message into queue */
pq->OSQEntries++; /* Update the nbr of entries in the queue */
if (pq->OSQIn == pq->OSQEnd) { /* Wrap IN ptr if we are at end of queue */
pq->OSQIn = pq->OSQStart;
}
OS_EXIT_CRITICAL();
return (OS_ERR_NONE);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* POST MESSAGE TO THE FRONT OF A QUEUE
*
* Description: This function sends a message to a queue but unlike OSQPost(), the message is posted at
* the front instead of the end of the queue. Using OSQPostFront() allows you to send
* 'priority' messages.
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue
*
* pmsg is a pointer to the message to send.
*
* Returns : OS_ERR_NONE The call was successful and the message was sent
* OS_ERR_Q_FULL If the queue cannot accept any more messages because it is full.
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
*
* Note(s) : As of V2.60, this function allows you to send NULL pointer messages.
*********************************************************************************************************
*/
#if OS_Q_POST_FRONT_EN > 0u
INT8U OSQPostFront (OS_EVENT *pevent,
void *pmsg)
{
OS_Q *pq;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#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_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0u) { /* See if any task pending on queue */
/* Ready highest priority task waiting on event */
(void)OS_EventTaskRdy(pevent, pmsg, OS_STAT_Q, OS_STAT_PEND_OK);
OS_EXIT_CRITICAL();
OS_Sched(); /* Find highest priority task ready to run */
return (OS_ERR_NONE);
}
pq = (OS_Q *)pevent->OSEventPtr; /* Point to queue control block */
if (pq->OSQEntries >= pq->OSQSize) { /* Make sure queue is not full */
OS_EXIT_CRITICAL();
return (OS_ERR_Q_FULL);
}
if (pq->OSQOut == pq->OSQStart) { /* Wrap OUT ptr if we are at the 1st queue entry */
pq->OSQOut = pq->OSQEnd;
}
pq->OSQOut--;
*pq->OSQOut = pmsg; /* Insert message into queue */
pq->OSQEntries++; /* Update the nbr of entries in the queue */
OS_EXIT_CRITICAL();
return (OS_ERR_NONE);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* POST MESSAGE TO A QUEUE
*
* Description: This function sends a message to a queue. This call has been added to reduce code size
* since it can replace both OSQPost() and OSQPostFront(). Also, this function adds the
* capability to broadcast a message to ALL tasks waiting on the message queue.
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue
*
* pmsg is a pointer to the message to send.
*
* opt determines the type of POST performed:
* OS_POST_OPT_NONE POST to a single waiting task
* (Identical to OSQPost())
* OS_POST_OPT_BROADCAST POST to ALL tasks that are waiting on the queue
* OS_POST_OPT_FRONT POST as LIFO (Simulates OSQPostFront())
* OS_POST_OPT_NO_SCHED Indicates that the scheduler will NOT be invoked
*
* Returns : OS_ERR_NONE The call was successful and the message was sent
* OS_ERR_Q_FULL If the queue cannot accept any more messages because it is full.
* OS_ERR_EVENT_TYPE If you didn't pass a pointer to a queue.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
*
* Warning : Interrupts can be disabled for a long time if you do a 'broadcast'. In fact, the
* interrupt disable time is proportional to the number of tasks waiting on the queue.
*********************************************************************************************************
*/
#if OS_Q_POST_OPT_EN > 0u
INT8U OSQPostOpt (OS_EVENT *pevent,
void *pmsg,
INT8U opt)
{
OS_Q *pq;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#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_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}
OS_ENTER_CRITICAL();
if (pevent->OSEventGrp != 0x00u) { /* See if any task pending on queue */
if ((opt & OS_POST_OPT_BROADCAST) != 0x00u) { /* Do we need to post msg to ALL waiting tasks ? */
while (pevent->OSEventGrp != 0u) { /* Yes, Post to ALL tasks waiting on queue */
(void)OS_EventTaskRdy(pevent, pmsg, OS_STAT_Q, OS_STAT_PEND_OK);
}
} else { /* No, Post to HPT waiting on queue */
(void)OS_EventTaskRdy(pevent, pmsg, OS_STAT_Q, OS_STAT_PEND_OK);
}
OS_EXIT_CRITICAL();
if ((opt & OS_POST_OPT_NO_SCHED) == 0u) { /* See if scheduler needs to be invoked */
OS_Sched(); /* Find highest priority task ready to run */
}
return (OS_ERR_NONE);
}
pq = (OS_Q *)pevent->OSEventPtr; /* Point to queue control block */
if (pq->OSQEntries >= pq->OSQSize) { /* Make sure queue is not full */
OS_EXIT_CRITICAL();
return (OS_ERR_Q_FULL);
}
if ((opt & OS_POST_OPT_FRONT) != 0x00u) { /* Do we post to the FRONT of the queue? */
if (pq->OSQOut == pq->OSQStart) { /* Yes, Post as LIFO, Wrap OUT pointer if we ... */
pq->OSQOut = pq->OSQEnd; /* ... are at the 1st queue entry */
}
pq->OSQOut--;
*pq->OSQOut = pmsg; /* Insert message into queue */
} else { /* No, Post as FIFO */
*pq->OSQIn++ = pmsg; /* Insert message into queue */
if (pq->OSQIn == pq->OSQEnd) { /* Wrap IN ptr if we are at end of queue */
pq->OSQIn = pq->OSQStart;
}
}
pq->OSQEntries++; /* Update the nbr of entries in the queue */
OS_EXIT_CRITICAL();
return (OS_ERR_NONE);
}
#endif
/*$PAGE*/
/*
*********************************************************************************************************
* QUERY A MESSAGE QUEUE
*
* Description: This function obtains information about a message queue.
*
* Arguments : pevent is a pointer to the event control block associated with the desired queue
*
* p_q_data is a pointer to a structure that will contain information about the message
* queue.
*
* Returns : OS_ERR_NONE The call was successful and the message was sent
* OS_ERR_EVENT_TYPE If you are attempting to obtain data from a non queue.
* OS_ERR_PEVENT_NULL If 'pevent' is a NULL pointer
* OS_ERR_PDATA_NULL If 'p_q_data' is a NULL pointer
*********************************************************************************************************
*/
#if OS_Q_QUERY_EN > 0u
INT8U OSQQuery (OS_EVENT *pevent,
OS_Q_DATA *p_q_data)
{
OS_Q *pq;
INT8U i;
OS_PRIO *psrc;
OS_PRIO *pdest;
#if OS_CRITICAL_METHOD == 3u /* Allocate storage for CPU status register */
OS_CPU_SR cpu_sr = 0u;
#endif
#if OS_ARG_CHK_EN > 0u
if (pevent == (OS_EVENT *)0) { /* Validate 'pevent' */
return (OS_ERR_PEVENT_NULL);
}
if (p_q_data == (OS_Q_DATA *)0) { /* Validate 'p_q_data' */
return (OS_ERR_PDATA_NULL);
}
#endif
if (pevent->OSEventType != OS_EVENT_TYPE_Q) { /* Validate event block type */
return (OS_ERR_EVENT_TYPE);
}
OS_ENTER_CRITICAL();
p_q_data->OSEventGrp = pevent->OSEventGrp; /* Copy message queue wait list */
psrc = &pevent->OSEventTbl[0];
pdest = &p_q_data->OSEventTbl[0];
for (i = 0u; i < OS_EVENT_TBL_SIZE; i++) {
*pdest++ = *psrc++;
}
pq = (OS_Q *)pevent->OSEventPtr;
if (pq->OSQEntries > 0u) {
p_q_data->OSMsg = *pq->OSQOut; /* Get next message to return if available */
} else {
p_q_data->OSMsg = (void *)0;
}
p_q_data->OSNMsgs = pq->OSQEntries;
p_q_data->OSQSize = pq->OSQSize;
OS_EXIT_CRITICAL();
return (OS_ERR_NONE);
}
#endif /* OS_Q_QUERY_EN */
/*$PAGE*/
/*
*********************************************************************************************************
* QUEUE MODULE INITIALIZATION
*
* Description : This function is called by uC/OS-II to initialize the message queue module. Your
* application MUST NOT call this function.
*
* Arguments : none
*
* Returns : none
*
* Note(s) : This function is INTERNAL to uC/OS-II and your application should not call it.
*********************************************************************************************************
*/
void OS_QInit (void)
{
#if OS_MAX_QS == 1u
OSQFreeList = &OSQTbl[0]; /* Only ONE queue! */
OSQFreeList->OSQPtr = (OS_Q *)0;
#endif
#if OS_MAX_QS >= 2u
INT16U ix;
INT16U ix_next;
OS_Q *pq1;
OS_Q *pq2;
OS_MemClr((INT8U *)&OSQTbl[0], sizeof(OSQTbl)); /* Clear the queue table */
for (ix = 0u; ix < (OS_MAX_QS - 1u); ix++) { /* Init. list of free QUEUE control blocks */
ix_next = ix + 1u;
pq1 = &OSQTbl[ix];
pq2 = &OSQTbl[ix_next];
pq1->OSQPtr = pq2;
}
pq1 = &OSQTbl[ix];
pq1->OSQPtr = (OS_Q *)0;
OSQFreeList = &OSQTbl[0];
#endif
}
#endif /* OS_Q_EN */
~~~
