/*
FreeRTOS.org V4.7.0 - Copyright (C) 2003-2007 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
See http://www.FreeRTOS.org for documentation, latest information, license
and contact details. Please ensure to read the configuration and relevant
port sections of the online documentation.
Also see http://www.SafeRTOS.com a version that has been certified for use
in safety critical systems, plus commercial licensing, development and
support options.
***************************************************************************
*/
#include <stdlib.h>
#include <string.h>
#include "FreeRTOS.h"
#include "task.h"
#include "croutine.h"
/*-----------------------------------------------------------
* PUBLIC LIST API documented in list.h
*----------------------------------------------------------*/
/* Constants used with the cRxLock and cTxLock structure members. */
#define queueUNLOCKED ( ( signed portBASE_TYPE ) -1 )
#define queueERRONEOUS_UNBLOCK ( -1 )
/* For internal use only. */
#define queueSEND_TO_BACK ( 0 )
#define queueSEND_TO_FRONT ( 1 )
/* Effectively make a union out of the xQUEUE structure. */
#define pxMutexHolder pcTail
#define uxQueueType pcHead
#define uxRecursiveCallCount pcReadFrom
#define queueQUEUE_IS_MUTEX NULL
/* Semaphores do not actually store or copy data, so have an items size of
zero. */
#define queueSEMAPHORE_QUEUE_ITEM_LENGTH ( 0 )
#define queueDONT_BLOCK ( ( portTickType ) 0 )
#define queueMUTEX_GIVE_BLOCK_TIME ( ( portTickType ) 0 )
/*
* Definition of the queue used by the scheduler.
* Items are queued by copy, not reference.
*/
typedef struct QueueDefinition
{
signed portCHAR *pcHead; /*< Points to the beginning of the queue storage area. */
signed portCHAR *pcTail; /*< Points to the byte at the end of the queue storage area. Once more byte is allocated than necessary to store the queue items, this is used as a marker. */
signed portCHAR *pcWriteTo; /*< Points to the free next place in the storage area. */
signed portCHAR *pcReadFrom; /*< Points to the last place that a queued item was read from. */
xList xTasksWaitingToSend; /*< List of tasks that are blocked waiting to post onto this queue. Stored in priority order. */
xList xTasksWaitingToReceive; /*< List of tasks that are blocked waiting to read from this queue. Stored in priority order. */
volatile unsigned portBASE_TYPE uxMessagesWaiting;/*< The number of items currently in the queue. */
unsigned portBASE_TYPE uxLength; /*< The length of the queue defined as the number of items it will hold, not the number of bytes. */
unsigned portBASE_TYPE uxItemSize; /*< The size of each items that the queue will hold. */
signed portBASE_TYPE xRxLock; /*< Stores the number of items received from the queue (removed from the queue) while the queue was locked. Set to queueUNLOCKED when the queue is not locked. */
signed portBASE_TYPE xTxLock; /*< Stores the number of items transmitted to the queue (added to the queue) while the queue was locked. Set to queueUNLOCKED when the queue is not locked. */
} xQUEUE;
/*-----------------------------------------------------------*/
/*
* Inside this file xQueueHandle is a pointer to a xQUEUE structure.
* To keep the definition private the API header file defines it as a
* pointer to void.
*/
typedef xQUEUE * xQueueHandle;
/*
* Prototypes for public functions are included here so we don't have to
* include the API header file (as it defines xQueueHandle differently). These
* functions are documented in the API header file.
*/
xQueueHandle xQueueCreate( unsigned portBASE_TYPE uxQueueLength, unsigned portBASE_TYPE uxItemSize );
signed portBASE_TYPE xQueueGenericSend( xQueueHandle xQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition );
unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle pxQueue );
void vQueueDelete( xQueueHandle xQueue );
signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle pxQueue, const void * const pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken, portBASE_TYPE xCopyPosition );
signed portBASE_TYPE xQueueGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking );
signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, const void * const pvBuffer, signed portBASE_TYPE *pxTaskWoken );
xQueueHandle xQueueCreateMutex( void );
xQueueHandle xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue, unsigned portBASE_TYPE uxInitialCount );
portBASE_TYPE xQueueTakeMutexRecursive( xQueueHandle xMutex, portTickType xBlockTime );
portBASE_TYPE xQueueGiveMutexRecursive( xQueueHandle xMutex );
signed portBASE_TYPE xQueueAltGenericSend( xQueueHandle pxQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition );
signed portBASE_TYPE xQueueAltGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking );
#if configUSE_CO_ROUTINES == 1
signed portBASE_TYPE xQueueCRSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xCoRoutinePreviouslyWoken );
signed portBASE_TYPE xQueueCRReceiveFromISR( xQueueHandle pxQueue, void *pvBuffer, signed portBASE_TYPE *pxTaskWoken );
signed portBASE_TYPE xQueueCRSend( xQueueHandle pxQueue, const void *pvItemToQueue, portTickType xTicksToWait );
signed portBASE_TYPE xQueueCRReceive( xQueueHandle pxQueue, void *pvBuffer, portTickType xTicksToWait );
#endif
/*
* Unlocks a queue locked by a call to prvLockQueue. Locking a queue does not
* prevent an ISR from adding or removing items to the queue, but does prevent
* an ISR from removing tasks from the queue event lists. If an ISR finds a
* queue is locked it will instead increment the appropriate queue lock count
* to indicate that a task may require unblocking. When the queue in unlocked
* these lock counts are inspected, and the appropriate action taken.
*/
static void prvUnlockQueue( xQueueHandle pxQueue );
/*
* Uses a critical section to determine if there is any data in a queue.
*
* @return pdTRUE if the queue contains no items, otherwise pdFALSE.
*/
static signed portBASE_TYPE prvIsQueueEmpty( const xQueueHandle pxQueue );
/*
* Uses a critical section to determine if there is any space in a queue.
*
* @return pdTRUE if there is no space, otherwise pdFALSE;
*/
static signed portBASE_TYPE prvIsQueueFull( const xQueueHandle pxQueue );
/*
* Copies an item into the queue, either at the front of the queue or the
* back of the queue.
*/
static void prvCopyDataToQueue( xQUEUE *pxQueue, const void *pvItemToQueue, portBASE_TYPE xPosition );
/*
* Copies an item out of a queue.
*/
static void prvCopyDataFromQueue( xQUEUE * const pxQueue, const void *pvBuffer );
/*-----------------------------------------------------------*/
/*
* Macro to mark a queue as locked. Locking a queue prevents an ISR from
* accessing the queue event lists.
*/
#define prvLockQueue( pxQueue ) \
{ \
taskENTER_CRITICAL(); \
++( pxQueue->xRxLock ); \
++( pxQueue->xTxLock ); \
taskEXIT_CRITICAL(); \
}
/*-----------------------------------------------------------*/
/*-----------------------------------------------------------
* PUBLIC QUEUE MANAGEMENT API documented in queue.h
*----------------------------------------------------------*/
xQueueHandle xQueueCreate( unsigned portBASE_TYPE uxQueueLength, unsigned portBASE_TYPE uxItemSize )
{
xQUEUE *pxNewQueue;
size_t xQueueSizeInBytes;
/* Allocate the new queue structure. */
if( uxQueueLength > ( unsigned portBASE_TYPE ) 0 )
{
pxNewQueue = ( xQUEUE * ) pvPortMalloc( sizeof( xQUEUE ) );
if( pxNewQueue != NULL )
{
/* Create the list of pointers to queue items. The queue is one byte
longer than asked for to make wrap checking easier/faster. */
xQueueSizeInBytes = ( size_t ) ( uxQueueLength * uxItemSize ) + ( size_t ) 1;
pxNewQueue->pcHead = ( signed portCHAR * ) pvPortMalloc( xQueueSizeInBytes );
if( pxNewQueue->pcHead != NULL )
{
/* Initialise the queue members as described above where the
queue type is defined. */
pxNewQueue->pcTail = pxNewQueue->pcHead + ( uxQueueLength * uxItemSize );
pxNewQueue->uxMessagesWaiting = 0;
pxNewQueue->pcWriteTo = pxNewQueue->pcHead;
pxNewQueue->pcReadFrom = pxNewQueue->pcHead + ( ( uxQueueLength - 1 ) * uxItemSize );
pxNewQueue->uxLength = uxQueueLength;
pxNewQueue->uxItemSize = uxItemSize;
pxNewQueue->xRxLock = queueUNLOCKED;
pxNewQueue->xTxLock = queueUNLOCKED;
/* Likewise ensure the event queues start with the correct state. */
vListInitialise( &( pxNewQueue->xTasksWaitingToSend ) );
vListInitialise( &( pxNewQueue->xTasksWaitingToReceive ) );
return pxNewQueue;
}
else
{
vPortFree( pxNewQueue );
}
}
}
/* Will only reach here if we could not allocate enough memory or no memory
was required. */
return NULL;
}
/*-----------------------------------------------------------*/
#if ( configUSE_MUTEXES == 1 )
xQueueHandle xQueueCreateMutex( void )
{
xQUEUE *pxNewQueue;
/* Allocate the new queue structure. */
pxNewQueue = ( xQUEUE * ) pvPortMalloc( sizeof( xQUEUE ) );
if( pxNewQueue != NULL )
{
/* Information required for priority inheritance. */
pxNewQueue->pxMutexHolder = NULL;
pxNewQueue->uxQueueType = queueQUEUE_IS_MUTEX;
/* Queues used as a mutex no data is actually copied into or out
of the queue. */
pxNewQueue->pcWriteTo = NULL;
pxNewQueue->pcReadFrom = NULL;
/* Each mutex has a length of 1 (like a binary semaphore) and
an item size of 0 as nothing is actually copied into or out
of the mutex. */
pxNewQueue->uxMessagesWaiting = 0;
pxNewQueue->uxLength = 1;
pxNewQueue->uxItemSize = 0;
pxNewQueue->xRxLock = queueUNLOCKED;
pxNewQueue->xTxLock = queueUNLOCKED;
/* Ensure the event queues start with the correct state. */
vListInitialise( &( pxNewQueue->xTasksWaitingToSend ) );
vListInitialise( &( pxNewQueue->xTasksWaitingToReceive ) );
/* Start with the semaphore in the expected state. */
xQueueGenericSend( pxNewQueue, NULL, 0, queueSEND_TO_BACK );
}
return pxNewQueue;
}
#endif /* configUSE_MUTEXES */
/*-----------------------------------------------------------*/
#if configUSE_RECURSIVE_MUTEXES == 1
portBASE_TYPE xQueueGiveMutexRecursive( xQueueHandle pxMutex )
{
portBASE_TYPE xReturn;
/* If this is the task that holds the mutex then pxMutexHolder will not
change outside of this task. If this task does not hold the mutex then
pxMutexHolder can never coincidentally equal the tasks handle, and as
this is the only condition we are interested in it does not matter if
pxMutexHolder is accessed simultaneously by another task. Therefore no
mutual exclusion is required to test the pxMutexHolder variable. */
if( pxMutex->pxMutexHolder == xTaskGetCurrentTaskHandle() )
{
/* uxRecursiveCallCount cannot be zero if pxMutexHolder is equal to
the task handle, therefore no underflow check is required. Also,
uxRecursiveCallCount is only modified by the mutex holder, and as
there can only be one, no mutual exclusion is required to modify the
uxRecursiveCallCount member. */
( pxMutex->uxRecursiveCallCount )--;
/* Have we unwound the call count? */
if( pxMutex->uxRecursiveCallCount == 0 )
{
/* Return the mutex. This will automatically unblock any other
task that might be waiting to access the mutex. */
xQueueGenericSend( pxMutex, NULL, queueMUTEX_GIVE_BLOCK_TIME, queueSEND_TO_BACK );
}
xReturn = pdPASS;
}
else
{
/* We cannot give the mutex because we are not the holder. */
xReturn = pdFAIL;
}
return xReturn;
}
#endif /* configUSE_RECURSIVE_MUTEXES */
/*-----------------------------------------------------------*/
#if configUSE_RECURSIVE_MUTEXES == 1
portBASE_TYPE xQueueTakeMutexRecursive( xQueueHandle pxMutex, portTickType xBlockTime )
{
portBASE_TYPE xReturn;
/* Comments regarding mutual exclusion as per those within
xQueueGiveMutexRecursive(). */
if( pxMutex->pxMutexHolder == xTaskGetCurrentTaskHandle() )
{
( pxMutex->uxRecursiveCallCount )++;
xReturn = pdPASS;
}
else
{
xReturn = xQueueGenericReceive( pxMutex, NULL, xBlockTime, pdFALSE );
/* pdPASS will only be returned if we successfully obtained the mutex,
we may have blocked to reach here. */
if( xReturn == pdPASS )
{
( pxMutex->uxRecursiveCallCount )++;
}
}
return xReturn;
}
#endif /* configUSE_RECURSIVE_MUTEXES */
/*-----------------------------------------------------------*/
#if configUSE_COUNTING_SEMAPHORES == 1
xQueueHandle xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue, unsigned portBASE_TYPE uxInitialCount, portBASE_TYPE xIsRecursive )
{
xQueueHandle pxHandle;
pxHandle = xQueueCreate( ( unsigned portBASE_TYPE ) uxCountValue, queueSEMAPHORE_QUEUE_ITEM_LENGTH );
if( pxHandle != NULL )
{
pxHandle->uxMessagesWaiting = uxInitialCount;
}
return pxHandle;
}
#endif /* configUSE_COUNTING_SEMAPHORES */
/*-----------------------------------------------------------*/
signed portBASE_TYPE xQueueGenericSend( xQueueHandle pxQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition )
{
signed portBASE_TYPE xReturn = pdPASS;
xTimeOutType xTimeOut;
/* Make sure other tasks do not access the queue. */
vTaskSuspendAll();
/* Capture the current time status for future reference. */
vTaskSetTimeOutState( &xTimeOut );
/* It is important that this is the only thread/ISR that modifies the
ready or delayed lists until xTaskResumeAll() is called. Places where
the ready/delayed lists are modified include:
+ vTaskDelay() - Nothing can call vTaskDelay as the scheduler is
suspended, vTaskDelay() cannot be called from an ISR.
+ vTaskPrioritySet() - Has a critical section around the access.
+ vTaskSwitchContext() - This will not get executed while the scheduler
is suspended.
+ prvCheckDelayedTasks() - This will not get executed while the
scheduler is suspended.
+ xTaskCreate() - Has a critical section around the access.
+ vTaskResume() - Has a critical section around the access.
+ xTaskResumeAll() - Has a critical section around the access.
+ xTaskRemoveFromEventList - Checks to see if the scheduler is
suspended. If so then the TCB being removed from the event is
removed from the event and added to the xPendingReadyList.
*/
/* Make sure interrupts do not access the queue event list. */
prvLockQueue( pxQueue );
/* It is important that interrupts to not access the event list of the
queue being modified here. Places where the event list is modified
include:
+ xQueueGenericSendFromISR(). This checks the lock on the queue to see
if it has access. If the queue is locked then the Tx lock count is
incremented to signify that a task waiting for data can be made ready
once the queue lock is removed. If the queue is not locked then
a task can be moved from the event list, but will not be removed
from the delayed list or placed in the ready list until the scheduler
is unlocked.
+ xQueueReceiveFromISR(). As per xQueueGenericSendFromISR().
*/
/* If the queue is already full we may have to block. */
do
{
if( prvIsQueueFull( pxQueue ) )
{
/* The queue is full - do we want to block or just leave without
posting? */
if( xTicksToWait > ( portTickType ) 0 )
{
/* We are going to place ourselves on the xTasksWaitingToSend event
list, and will get woken should the delay expire, or space become
available on the queue.
As detailed above we do not require mutual exclusion on the event
list as nothing else can modify it or the ready lists while we
have the scheduler suspended and queue locked.
It is possible that an ISR has removed data from the queue since we
checked if any was available. If this is the case then the data
will have been copied from the queue, and the queue variables
updated, but the event list will not yet have been checked to see if
anything is waiting as the queue is locked. */
vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );
/* Force a context switch now as we are blocked. We can do
this from within a critical section as the task we are
switching to has its own context. When we return here (i.e. we
unblock) we will leave the critical section as normal.
It is possible that an ISR has caused an event on an unrelated and
unlocked queue. If this was the case then the event list for that
queue will have been updated but the ready lists left unchanged -
instead the readied task will have been added to the pending ready
list. */
taskENTER_CRITICAL();
{
/* We can safely unlock the queue and scheduler here as
interrupts are disabled. We must not yield with anything
locked, but we can yield from within a critical section.
Tasks that have been placed on the pending ready list cannot
be tasks that are waiting for events on this queue. See
in comment xTaskRemoveFromEventList(). */
prvUnlockQueue( pxQueue );
/* Resuming the scheduler may cause a yield. If so then there
is no point yielding again here. */
if( !xTaskResumeAll() )
{
taskYIELD();
}
/* We want to check to see if the queue is still full
before leaving the critical section. This is to prevent
this task placing an item into the queue due to an
interrupt making space on the queue between critical
sections (when there might be a higher priority task
blocked on the queue that cannot run yet because the
scheduler gets suspended). */
if( pxQueue->uxMessagesWaiting == pxQueue->uxLength )
{
/* We unblocked but there is no space in the queue,
we probably timed out. */
xReturn = errQUEUE_FULL;
}
/* Before leaving the critical section we have to ensure
exclusive access again. */
vTaskSuspendAll();
prvLockQueue( pxQueue );
}
taskEXIT_CRITICAL();
}
}
/* If xReturn is errQUEUE_FULL then we unblocked when the queue
was still full. Don't check it again now as it is possible that
an interrupt has removed an item from the queue since we left the
critical section and we don't want to write to the queue in case
there is a task of higher priority blocked waiting for space to
be available on the queue. If this is the case the higher priority
task will execute when the scheduler is unsupended. */
if( xReturn != errQUEUE_FULL )
{
/* When we are here it is possible that we unblocked as space became
available on the queue. It is also possible that an ISR posted to the
queue since we left the critical section, so it may be that again there
is no space. This would only happen if a task and ISR post onto the
same queue. */
taskENTER_CRITICAL();
{
if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
{
/* There is room in the queue, copy the data into the queue. */
prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );
xReturn = pdPASS;
/* Update the TxLock count so prvUnlockQueue knows to check for
tasks waiting for data to become available in the queue. */
++( pxQueue->xTxLock );
}
else
{
xReturn = errQUEUE_FULL;
}
}
taskEXIT_CRITICAL();
}
if( xReturn == errQUEUE_FULL )
{
if( xTicksToWait > 0 )
{
if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
{
xReturn = queueERRONEOUS_UNBLOCK;
}
}
}
}
while( xReturn == queueERRONEOUS_UNBLOCK );
prvUnlockQueue( pxQueue );
xTaskResumeAll();
return xReturn;
}
/*-----------------------------------------------------------*/
#if configUSE_ALTERNATIVE_API == 1
signed portBASE_TYPE xQueueAltGenericSend( xQueueHandle pxQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition )
{
signed portBASE_TYPE xReturn;
xTimeOutType xTimeOut;
/* The source code that implements the alternative (Alt) API is much
simpler because it executes everything from within a critical section.
This is the approach taken by many other RTOSes, but FreeRTOS.org has the
preferred fully featured API too. The fully featured API has more
complex code that takes longer to execute, but makes much less use of
critical sections. Therefore the alternative API sacrifices interrupt
responsiveness to gain execution speed, whereas the fully featured API
sacrifices execution speed to ensure better interrupt responsiveness. */
taskENTER_CRITICAL();
{
/* Capture the current time status for future reference. */
vTaskSetTimeOutState( &xTimeOut );
/* If the queue is already full we may have to block. */
do
{
if( pxQueue->uxMessagesWaiting == pxQueue->uxLength )
{
/* The queue is full - do we want to block or just leave without
posting? */
if( xTicksToWait > ( portTickType ) 0 )
{
/* We are going to place ourselves on the xTasksWaitingToSend
event list, and will get woken should the delay expire, or
space become available on the queue. */
vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToSend ), xTicksToWait );
/* Force a context switch now as we are blocked. We can do
this from within a critical section as the task we are
switching to has its own context. When we return here (i.e.
we unblock) we will leave the critical section as normal. */
taskYIELD();
}
}
if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
{
/* There is room in the queue, copy the data into the queue. */
prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );
xReturn = pdPASS;
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
/* The task waiting has a higher priority. */
taskYIELD();
}
}
}
else
{
xReturn = errQUEUE_FULL;
if( xTicksToWait > 0 )
{
if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
{
/* Another task must have accessed the queue between
this task unblocking and actually executing. */
xReturn = queueERRONEOUS_UNBLOCK;
}
}
}
}
while( xReturn == queueERRONEOUS_UNBLOCK );
}
taskEXIT_CRITICAL();
return xReturn;
}
#endif /* configUSE_ALTERNATIVE_API */
/*-----------------------------------------------------------*/
#if configUSE_ALTERNATIVE_API == 1
signed portBASE_TYPE xQueueAltGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking )
{
signed portBASE_TYPE xReturn = pdTRUE;
xTimeOutType xTimeOut;
signed portCHAR *pcOriginalReadPosition;
/* The source code that implements the alternative (Alt) API is much
simpler because it executes everything from within a critical section.
This is the approach taken by many other RTOSes, but FreeRTOS.org has the
preferred fully featured API too. The fully featured API has more
complex code that takes longer to execute, but makes much less use of
critical sections. Therefore the alternative API sacrifices interrupt
responsiveness to gain execution speed, whereas the fully featured API
sacrifices execution speed to ensure better interrupt responsiveness. */
taskENTER_CRITICAL();
{
/* Capture the current time status for future reference. */
vTaskSetTimeOutState( &xTimeOut );
do
{
/* If there are no messages in the queue we may have to block. */
if( pxQueue->uxMessagesWaiting == ( unsigned portBASE_TYPE ) 0 )
{
/* There are no messages in the queue, do we want to block or just
leave with nothing? */
if( xTicksToWait > ( portTickType ) 0 )
{
#if ( configUSE_MUTEXES == 1 )
{
if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
{
vTaskPriorityInherit( ( void * const ) pxQueue->pxMutexHolder );
}
}
#endif
vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );
taskYIELD();
}
}
if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
{
/* Remember our read position in case we are just peeking. */
pcOriginalReadPosition = pxQueue->pcReadFrom;
prvCopyDataFromQueue( pxQueue, pvBuffer );
if( xJustPeeking == pdFALSE )
{
/* We are actually removing data. */
--( pxQueue->uxMessagesWaiting );
#if ( configUSE_MUTEXES == 1 )
{
if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
{
/* Record the information required to implement
priority inheritance should it become necessary. */
pxQueue->pxMutexHolder = xTaskGetCurrentTaskHandle();
}
}
#endif
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
{
/* The task waiting has a higher priority. */
taskYIELD();
}
}
}
else
{
/* We are not removing the data, so reset our read
pointer. */
pxQueue->pcReadFrom = pcOriginalReadPosition;
}
xReturn = pdPASS;
}
else
{
xReturn = errQUEUE_EMPTY;
if( xTicksToWait > 0 )
{
if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
{
xReturn = queueERRONEOUS_UNBLOCK;
}
}
}
} while( xReturn == queueERRONEOUS_UNBLOCK );
}
taskEXIT_CRITICAL();
return xReturn;
}
#endif /* configUSE_ALTERNATIVE_API */
/*-----------------------------------------------------------*/
signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle pxQueue, const void * const pvItemToQueue, signed portBASE_TYPE xTaskPreviouslyWoken, portBASE_TYPE xCopyPosition )
{
/* Similar to xQueueGenericSend, except we don't block if there is no room
in the queue. Also we don't directly wake a task that was blocked on a
queue read, instead we return a flag to say whether a context switch is
required or not (i.e. has a task with a higher priority than us been woken
by this post). */
if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
{
prvCopyDataToQueue( pxQueue, pvItemToQueue, xCopyPosition );
/* If the queue is locked we do not alter the event list. This will
be done when the queue is unlocked later. */
if( pxQueue->xTxLock == queueUNLOCKED )
{
/* We only want to wake one task per ISR, so check that a task has
not already been woken. */
if( !xTaskPreviouslyWoken )
{
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
/* The task waiting has a higher priority so record that a
context switch is required. */
return pdTRUE;
}
}
}
}
else
{
/* Increment the lock count so the task that unlocks the queue
knows that data was posted while it was locked. */
++( pxQueue->xTxLock );
}
}
return xTaskPreviouslyWoken;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xQueueGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking )
{
signed portBASE_TYPE xReturn = pdTRUE;
xTimeOutType xTimeOut;
signed portCHAR *pcOriginalReadPosition;
/* This function is very similar to xQueueGenericSend(). See comments
within xQueueGenericSend() for a more detailed explanation.
Make sure other tasks do not access the queue. */
vTaskSuspendAll();
/* Capture the current time status for future reference. */
vTaskSetTimeOutState( &xTimeOut );
/* Make sure interrupts do not access the queue. */
prvLockQueue( pxQueue );
do
{
/* If there are no messages in the queue we may have to block. */
if( prvIsQueueEmpty( pxQueue ) )
{
/* There are no messages in the queue, do we want to block or just
leave with nothing? */
if( xTicksToWait > ( portTickType ) 0 )
{
#if ( configUSE_MUTEXES == 1 )
{
if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
{
portENTER_CRITICAL();
vTaskPriorityInherit( ( void * const ) pxQueue->pxMutexHolder );
portEXIT_CRITICAL();
}
}
#endif
vTaskPlaceOnEventList( &( pxQueue->xTasksWaitingToReceive ), xTicksToWait );
taskENTER_CRITICAL();
{
prvUnlockQueue( pxQueue );
if( !xTaskResumeAll() )
{
taskYIELD();
}
if( pxQueue->uxMessagesWaiting == ( unsigned portBASE_TYPE ) 0 )
{
/* We unblocked but the queue is empty. We probably
timed out. */
xReturn = errQUEUE_EMPTY;
}
vTaskSuspendAll();
prvLockQueue( pxQueue );
}
taskEXIT_CRITICAL();
}
}
if( xReturn != errQUEUE_EMPTY )
{
taskENTER_CRITICAL();
{
if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
{
/* Remember our read position in case we are just peeking. */
pcOriginalReadPosition = pxQueue->pcReadFrom;
prvCopyDataFromQueue( pxQueue, pvBuffer );
if( xJustPeeking == pdFALSE )
{
/* We are actually removing data. */
--( pxQueue->uxMessagesWaiting );
/* Increment the lock count so prvUnlockQueue knows to check for
tasks waiting for space to become available on the queue. */
++( pxQueue->xRxLock );
#if ( configUSE_MUTEXES == 1 )
{
if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
{
/* Record the information required to implement
priority inheritance should it become necessary. */
pxQueue->pxMutexHolder = xTaskGetCurrentTaskHandle();
}
}
#endif
}
else
{
/* We are not removing the data, so reset our read
pointer. */
pxQueue->pcReadFrom = pcOriginalReadPosition;
/* The data is being left in the queue, so increment the
lock count so prvUnlockQueue knows to check for other
tasks waiting for the data to be available. */
++( pxQueue->xTxLock );
}
xReturn = pdPASS;
}
else
{
xReturn = errQUEUE_EMPTY;
}
}
taskEXIT_CRITICAL();
}
if( xReturn == errQUEUE_EMPTY )
{
if( xTicksToWait > 0 )
{
if( xTaskCheckForTimeOut( &xTimeOut, &xTicksToWait ) == pdFALSE )
{
xReturn = queueERRONEOUS_UNBLOCK;
}
}
}
} while( xReturn == queueERRONEOUS_UNBLOCK );
/* We no longer require exclusive access to the queue. */
prvUnlockQueue( pxQueue );
xTaskResumeAll();
return xReturn;
}
/*-----------------------------------------------------------*/
signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, const void * const pvBuffer, signed portBASE_TYPE *pxTaskWoken )
{
signed portBASE_TYPE xReturn;
/* We cannot block from an ISR, so check there is data available. */
if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
{
prvCopyDataFromQueue( pxQueue, pvBuffer );
--( pxQueue->uxMessagesWaiting );
/* If the queue is locked we will not modify the event list. Instead
we update the lock count so the task that unlocks the queue will know
that an ISR has removed data while the queue was locked. */
if( pxQueue->xRxLock == queueUNLOCKED )
{
/* We only want to wake one task per ISR, so check that a task has
not already been woken. */
if( !( *pxTaskWoken ) )
{
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
{
/* The task waiting has a higher priority than us so
force a context switch. */
*pxTaskWoken = pdTRUE;
}
}
}
}
else
{
/* Increment the lock count so the task that unlocks the queue
knows that data was removed while it was locked. */
++( pxQueue->xRxLock );
}
xReturn = pdPASS;
}
else
{
xReturn = pdFAIL;
}
return xReturn;
}
/*-----------------------------------------------------------*/
unsigned portBASE_TYPE uxQueueMessagesWaiting( const xQueueHandle pxQueue )
{
unsigned portBASE_TYPE uxReturn;
taskENTER_CRITICAL();
uxReturn = pxQueue->uxMessagesWaiting;
taskEXIT_CRITICAL();
return uxReturn;
}
/*-----------------------------------------------------------*/
void vQueueDelete( xQueueHandle pxQueue )
{
vPortFree( pxQueue->pcHead );
vPortFree( pxQueue );
}
/*-----------------------------------------------------------*/
static void prvCopyDataToQueue( xQUEUE *pxQueue, const void *pvItemToQueue, portBASE_TYPE xPosition )
{
if( pxQueue->uxItemSize == 0 )
{
#if ( configUSE_MUTEXES == 1 )
{
if( pxQueue->uxQueueType == queueQUEUE_IS_MUTEX )
{
/* The mutex is no longer being held. */
vTaskPriorityDisinherit( ( void * const ) pxQueue->pxMutexHolder );
pxQueue->pxMutexHolder = NULL;
}
}
#endif
}
else if( xPosition == queueSEND_TO_BACK )
{
memcpy( ( void * ) pxQueue->pcWriteTo, pvItemToQueue, ( unsigned ) pxQueue->uxItemSize );
pxQueue->pcWriteTo += pxQueue->uxItemSize;
if( pxQueue->pcWriteTo >= pxQueue->pcTail )
{
pxQueue->pcWriteTo = pxQueue->pcHead;
}
}
else
{
memcpy( ( void * ) pxQueue->pcReadFrom, pvItemToQueue, ( unsigned ) pxQueue->uxItemSize );
pxQueue->pcReadFrom -= pxQueue->uxItemSize;
if( pxQueue->pcReadFrom < pxQueue->pcHead )
{
pxQueue->pcReadFrom = ( pxQueue->pcTail - pxQueue->uxItemSize );
}
}
++( pxQueue->uxMessagesWaiting );
}
/*-----------------------------------------------------------*/
static void prvCopyDataFromQueue( xQUEUE * const pxQueue, const void *pvBuffer )
{
if( pxQueue->uxQueueType != queueQUEUE_IS_MUTEX )
{
pxQueue->pcReadFrom += pxQueue->uxItemSize;
if( pxQueue->pcReadFrom >= pxQueue->pcTail )
{
pxQueue->pcReadFrom = pxQueue->pcHead;
}
memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->pcReadFrom, ( unsigned ) pxQueue->uxItemSize );
}
}
/*-----------------------------------------------------------*/
static void prvUnlockQueue( xQueueHandle pxQueue )
{
/* THIS FUNCTION MUST BE CALLED WITH THE SCHEDULER SUSPENDED. */
/* The lock counts contains the number of extra data items placed or
removed from the queue while the queue was locked. When a queue is
locked items can be added or removed, but the event lists cannot be
updated. */
taskENTER_CRITICAL();
{
--( pxQueue->xTxLock );
/* See if data was added to the queue while it was locked. */
if( pxQueue->xTxLock > queueUNLOCKED )
{
pxQueue->xTxLock = queueUNLOCKED;
/* Data was posted while the queue was locked. Are any tasks
blocked waiting for data to become available? */
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )
{
/* Tasks that are removed from the event list will get added to
the pending ready list as the scheduler is still suspended. */
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
/* The task waiting has a higher priority so record that a
context switch is required. */
vTaskMissedYield();
}
}
}
}
taskEXIT_CRITICAL();
/* Do the same for the Rx lock. */
taskENTER_CRITICAL();
{
--( pxQueue->xRxLock );
if( pxQueue->xRxLock > queueUNLOCKED )
{
pxQueue->xRxLock = queueUNLOCKED;
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) )
{
if( xTaskRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
{
vTaskMissedYield();
}
}
}
}
taskEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/
static signed portBASE_TYPE prvIsQueueEmpty( const xQueueHandle pxQueue )
{
signed portBASE_TYPE xReturn;
taskENTER_CRITICAL();
xReturn = ( pxQueue->uxMessagesWaiting == ( unsigned portBASE_TYPE ) 0 );
taskEXIT_CRITICAL();
return xReturn;
}
/*-----------------------------------------------------------*/
static signed portBASE_TYPE prvIsQueueFull( const xQueueHandle pxQueue )
{
signed portBASE_TYPE xReturn;
taskENTER_CRITICAL();
xReturn = ( pxQueue->uxMessagesWaiting == pxQueue->uxLength );
taskEXIT_CRITICAL();
return xReturn;
}
/*-----------------------------------------------------------*/
#if configUSE_CO_ROUTINES == 1
signed portBASE_TYPE xQueueCRSend( xQueueHandle pxQueue, const void *pvItemToQueue, portTickType xTicksToWait )
{
signed portBASE_TYPE xReturn;
/* If the queue is already full we may have to block. A critical section
is required to prevent an interrupt removing something from the queue
between the check to see if the queue is full and blocking on the queue. */
portDISABLE_INTERRUPTS();
{
if( prvIsQueueFull( pxQueue ) )
{
/* The queue is full - do we want to block or just leave without
posting? */
if( xTicksToWait > ( portTickType ) 0 )
{
/* As this is called from a coroutine we cannot block directly, but
return indicating that we need to block. */
vCoRoutineAddToDelayedList( xTicksToWait, &( pxQueue->xTasksWaitingToSend ) );
portENABLE_INTERRUPTS();
return errQUEUE_BLOCKED;
}
else
{
portENABLE_INTERRUPTS();
return errQUEUE_FULL;
}
}
}
portENABLE_INTERRUPTS();
portNOP();
portDISABLE_INTERRUPTS();
{
if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
{
/* There is room in the queue, copy the data into the queue. */
prvCopyDataToQueue( pxQueue, pvItemToQueue, queueSEND_TO_BACK );
xReturn = pdPASS;
/* Were any co-routines waiting for data to become available? */
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )
{
/* In this instance the co-routine could be placed directly
into the ready list as we are within a critical section.
Instead the same pending ready list mechanism is used as if
the event were caused from within an interrupt. */
if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
/* The co-routine waiting has a higher priority so record
that a yield might be appropriate. */
xReturn = errQUEUE_YIELD;
}
}
}
else
{
xReturn = errQUEUE_FULL;
}
}
portENABLE_INTERRUPTS();
return xReturn;
}
#endif
/*-----------------------------------------------------------*/
#if configUSE_CO_ROUTINES == 1
signed portBASE_TYPE xQueueCRReceive( xQueueHandle pxQueue, void *pvBuffer, portTickType xTicksToWait )
{
signed portBASE_TYPE xReturn;
/* If the queue is already empty we may have to block. A critical section
is required to prevent an interrupt adding something to the queue
between the check to see if the queue is empty and blocking on the queue. */
portDISABLE_INTERRUPTS();
{
if( pxQueue->uxMessagesWaiting == ( unsigned portBASE_TYPE ) 0 )
{
/* There are no messages in the queue, do we want to block or just
leave with nothing? */
if( xTicksToWait > ( portTickType ) 0 )
{
/* As this is a co-routine we cannot block directly, but return
indicating that we need to block. */
vCoRoutineAddToDelayedList( xTicksToWait, &( pxQueue->xTasksWaitingToReceive ) );
portENABLE_INTERRUPTS();
return errQUEUE_BLOCKED;
}
else
{
portENABLE_INTERRUPTS();
return errQUEUE_FULL;
}
}
}
portENABLE_INTERRUPTS();
portNOP();
portDISABLE_INTERRUPTS();
{
if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
{
/* Data is available from the queue. */
pxQueue->pcReadFrom += pxQueue->uxItemSize;
if( pxQueue->pcReadFrom >= pxQueue->pcTail )
{
pxQueue->pcReadFrom = pxQueue->pcHead;
}
--( pxQueue->uxMessagesWaiting );
memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->pcReadFrom, ( unsigned ) pxQueue->uxItemSize );
xReturn = pdPASS;
/* Were any co-routines waiting for space to become available? */
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) )
{
/* In this instance the co-routine could be placed directly
into the ready list as we are within a critical section.
Instead the same pending ready list mechanism is used as if
the event were caused from within an interrupt. */
if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
{
xReturn = errQUEUE_YIELD;
}
}
}
else
{
xReturn = pdFAIL;
}
}
portENABLE_INTERRUPTS();
return xReturn;
}
#endif
/*-----------------------------------------------------------*/
#if configUSE_CO_ROUTINES == 1
signed portBASE_TYPE xQueueCRSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xCoRoutinePreviouslyWoken )
{
/* Cannot block within an ISR so if there is no space on the queue then
exit without doing anything. */
if( pxQueue->uxMessagesWaiting < pxQueue->uxLength )
{
prvCopyDataToQueue( pxQueue, pvItemToQueue, queueSEND_TO_BACK );
/* We only want to wake one co-routine per ISR, so check that a
co-routine has not already been woken. */
if( !xCoRoutinePreviouslyWoken )
{
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToReceive ) ) )
{
if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToReceive ) ) != pdFALSE )
{
return pdTRUE;
}
}
}
}
return xCoRoutinePreviouslyWoken;
}
#endif
/*-----------------------------------------------------------*/
#if configUSE_CO_ROUTINES == 1
signed portBASE_TYPE xQueueCRReceiveFromISR( xQueueHandle pxQueue, void *pvBuffer, signed portBASE_TYPE *pxCoRoutineWoken )
{
signed portBASE_TYPE xReturn;
/* We cannot block from an ISR, so check there is data available. If
not then just leave without doing anything. */
if( pxQueue->uxMessagesWaiting > ( unsigned portBASE_TYPE ) 0 )
{
/* Copy the data from the queue. */
pxQueue->pcReadFrom += pxQueue->uxItemSize;
if( pxQueue->pcReadFrom >= pxQueue->pcTail )
{
pxQueue->pcReadFrom = pxQueue->pcHead;
}
--( pxQueue->uxMessagesWaiting );
memcpy( ( void * ) pvBuffer, ( void * ) pxQueue->pcReadFrom, ( unsigned ) pxQueue->uxItemSize );
if( !( *pxCoRoutineWoken ) )
{
if( !listLIST_IS_EMPTY( &( pxQueue->xTasksWaitingToSend ) ) )
{
if( xCoRoutineRemoveFromEventList( &( pxQueue->xTasksWaitingToSend ) ) != pdFALSE )
{
*pxCoRoutineWoken = pdTRUE;
}
}
}
xReturn = pdPASS;
}
else
{
xReturn = pdFAIL;
}
return xReturn;
}
#endif
/*-----------------------------------------------------------*/