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Counting semaphore demo added.
This commit is contained in:
Richard Barry
parent
a8eabeabbb
commit
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11 changed files with 581 additions and 202 deletions
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@ -116,6 +116,10 @@
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#define configUSE_MUTEXES 0
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#endif
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#ifndef configUSE_COUNTING_SEMAPHORES
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#define configUSE_COUNTING_SEMAPHORES 0
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#endif
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#if ( configUSE_MUTEXES == 1 )
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/* xTaskGetCurrentTaskHandle is used by the priority inheritance mechanism
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within the mutex implementation so must be available if mutexes are used. */
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@ -1175,10 +1175,11 @@ signed portBASE_TYPE xQueueCRSend( xQueueHandle pxQueue, const void *pvItemToQue
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signed portBASE_TYPE xQueueCRReceive( xQueueHandle pxQueue, void *pvBuffer, portTickType xTicksToWait );
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/*
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* For internal use only. Use xSemaphoreCreateMutex() instead of calling
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* this function directly.
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* For internal use only. Use xSemaphoreCreateMutex() or
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* xSemaphoreCreateCounting() instead of calling these functions directly.
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*/
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xQueueHandle xQueueCreateMutex( void );
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xQueueHandle xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue, unsigned portBASE_TYPE uxInitialCount );
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#ifdef __cplusplus
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}
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@ -34,11 +34,11 @@
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***************************************************************************
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*/
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#include "queue.h"
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#ifndef SEMAPHORE_H
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#define SEMAPHORE_H
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#include "queue.h"
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typedef xQueueHandle xSemaphoreHandle;
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#define semBINARY_SEMAPHORE_QUEUE_LENGTH ( ( unsigned portCHAR ) 1 )
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@ -84,12 +84,12 @@ typedef xQueueHandle xSemaphoreHandle;
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* \defgroup vSemaphoreCreateBinary vSemaphoreCreateBinary
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* \ingroup Semaphores
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*/
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#define vSemaphoreCreateBinary( xSemaphore ) { \
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xSemaphore = xQueueCreate( ( unsigned portCHAR ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH ); \
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if( xSemaphore != NULL ) \
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{ \
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xSemaphoreGive( xSemaphore ); \
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} \
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#define vSemaphoreCreateBinary( xSemaphore ) { \
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xSemaphore = xQueueCreate( ( unsigned portBASE_TYPE ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH ); \
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if( xSemaphore != NULL ) \
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{ \
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xSemaphoreGive( xSemaphore ); \
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} \
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}
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/**
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@ -341,6 +341,66 @@ typedef xQueueHandle xSemaphoreHandle;
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*/
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#define xSemaphoreCreateMutex() xQueueCreateMutex()
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/**
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* semphr. h
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* <pre>vSemaphoreCreateCounting( xSemaphoreHandle xSemaphore, unsigned portBASE_TYPE uxMaxCount )</pre>
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*
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* <i>Macro</i> that creates a counting semaphore by using the existing
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* queue mechanism. The queue length is used as the maximum count. The data
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* size is 0 as we don't want to actually store any data - we just want to
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* know if the queue is empty or full.
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*
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* Counting semaphores are typically used for two things:
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*
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* 1) Counting events.
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*
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* In this usage scenario an event handler will 'give' a semphore each time
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* an event occurs (incrementing the semaphore count value), and a handler
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* task will 'take' a semaphore each time it processes an event
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* (decrementing the semaphore count value). The count value is therefore
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* the difference between the number of events that have occurred and the
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* number that have been processed. In this case it is desirable for the
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* initial count value to be zero.
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*
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* 2) Resource management.
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*
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* In this usage scenario the count value indicates the number of resources
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* available. To obtain control of a resource a task must first obtain a
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* semphoare - decrementing the semaphore count value. When the count value
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* reaches zero there are no free resources. When a task finishes with the
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* resource it 'gives' the semahore back - incrementing the semaphore count
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* value. In this case it is desirable for the initial count value to be
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* equal to the maximum count value, indicating that all resources are free.
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*
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* @param uxMaxCount The maximum count value that can be reached. When the
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* semaphore reaches this value it can nolonger be 'given'.
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* @param uxInitialCount
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*
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* @return Handle to the created semaphore. Should be of type xSemaphoreHandle.
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*
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* Example usage:
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<pre>
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xSemaphoreHandle xSemaphore;
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void vATask( void * pvParameters )
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{
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xSemaphoreHandle xSemaphore = NULL;
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// Semaphore cannot be used before a call to vSemaphoreCreateCounting().
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// This is a macro so pass the variable in directly.
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vSemaphoreCreateBinary( xSemaphore, );
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if( xSemaphore != NULL )
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{
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// The semaphore was created successfully.
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// The semaphore can now be used.
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}
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}
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</pre>
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* \defgroup xSemaphoreCreateCounting xSemaphoreCreateCounting
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* \ingroup Semaphores
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*/
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#define xSemaphoreCreateCounting( uxCountValue, uxInitialCount ) xQueueCreateCountingSemaphore( uxCountValue, uxInitialCount )
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#endif /* SEMAPHORE_H */
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@ -114,7 +114,7 @@ portSTACK_TYPE *pxOriginalTOS;
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*pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
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*pxTopOfStack = ( portSTACK_TYPE ) 0x00000000; /* R14 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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pxTopOfStack--;
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@ -34,49 +34,6 @@
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***************************************************************************
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*/
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/*
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Changes from V1.01
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+ More use of 8bit data types.
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+ Function name prefixes changed where the data type returned has changed.
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Changed from V2.0.0
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+ Added the queue locking mechanism and make more use of the scheduler
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suspension feature to minimise the time interrupts have to be disabled
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when accessing a queue.
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Changed from V2.2.0
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+ Explicit use of 'signed' qualifier on portCHAR types added.
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Changes from V3.0.0
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+ API changes as described on the FreeRTOS.org WEB site.
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Changes from V3.2.3
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+ Added the queue functions that can be used from co-routines.
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Changes from V4.0.5
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+ Added a loop within xQueueSend() and xQueueReceive() to prevent the
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functions exiting when a block time remains and the function has
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not completed.
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Changes from V4.1.2:
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+ BUG FIX: Removed the call to prvIsQueueEmpty from within xQueueCRReceive
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as it exited with interrupts enabled. Thanks Paul Katz.
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Changes from V4.1.3:
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+ Modified xQueueSend() and xQueueReceive() to handle the (very unlikely)
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case whereby a task unblocking due to a temporal event can remove/send an
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item from/to a queue when a higher priority task is still blocked on the
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queue. This modification is a result of the SafeRTOS testing.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "FreeRTOS.h"
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@ -100,6 +57,11 @@ Changes from V4.1.3:
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#define uxQueueType pcHead
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#define queueQUEUE_IS_MUTEX NULL
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/* Semaphores do not actually store or copy data, so have an items size of
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zero. */
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#define queueSEMAPHORE_QUEUE_ITEM_LENGTH ( 0 )
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#define queueDONT_BLOCK ( ( portTickType ) 0 )
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/*
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* Definition of the queue used by the scheduler.
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* Items are queued by copy, not reference.
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@ -144,6 +106,7 @@ signed portBASE_TYPE xQueueGenericSendFromISR( xQueueHandle pxQueue, const void
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signed portBASE_TYPE xQueueGenericReceive( xQueueHandle pxQueue, const void * const pvBuffer, portTickType xTicksToWait, portBASE_TYPE xJustPeeking );
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signed portBASE_TYPE xQueueReceiveFromISR( xQueueHandle pxQueue, const void * const pvBuffer, signed portBASE_TYPE *pxTaskWoken );
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xQueueHandle xQueueCreateMutex( void );
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xQueueHandle xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue, unsigned portBASE_TYPE uxInitialCount );
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#if configUSE_CO_ROUTINES == 1
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signed portBASE_TYPE xQueueCRSendFromISR( xQueueHandle pxQueue, const void *pvItemToQueue, signed portBASE_TYPE xCoRoutinePreviouslyWoken );
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@ -296,6 +259,25 @@ size_t xQueueSizeInBytes;
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#endif /* configUSE_MUTEXES */
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/*-----------------------------------------------------------*/
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#if configUSE_COUNTING_SEMAPHORES == 1
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xQueueHandle xQueueCreateCountingSemaphore( unsigned portBASE_TYPE uxCountValue, unsigned portBASE_TYPE uxInitialCount )
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{
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xQueueHandle pxHandle;
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pxHandle = xQueueCreate( ( unsigned portBASE_TYPE ) uxCountValue, queueSEMAPHORE_QUEUE_ITEM_LENGTH );
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if( pxHandle != NULL )
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{
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pxHandle->uxMessagesWaiting = uxInitialCount;
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}
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return pxHandle;
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}
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#endif /* configUSE_COUNTING_SEMAPHORES */
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/*-----------------------------------------------------------*/
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signed portBASE_TYPE xQueueGenericSend( xQueueHandle pxQueue, const void * const pvItemToQueue, portTickType xTicksToWait, portBASE_TYPE xCopyPosition )
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{
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signed portBASE_TYPE xReturn = pdPASS;
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