semphr.h File Reference

#include "queue.h"

Macros
#define	semBINARY_SEMAPHORE_QUEUE_LENGTH   ( ( unsigned char ) 1U )
#define	semGIVE_BLOCK_TIME   ( ( portTickType ) 0U )
#define	semSEMAPHORE_QUEUE_ITEM_LENGTH   ( ( unsigned char ) 0U )
#define	vSemaphoreCreateBinary(xSemaphore)
#define	vSemaphoreDelete(xSemaphore)   vQueueDelete( ( xQueueHandle ) ( xSemaphore ) )
#define	xSemaphoreAltGive(xSemaphore)   xQueueAltGenericSend( ( xQueueHandle ) ( xSemaphore ), NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
#define	xSemaphoreAltTake(xSemaphore, xBlockTime)   xQueueAltGenericReceive( ( xQueueHandle ) ( xSemaphore ), NULL, ( xBlockTime ), pdFALSE )
#define	xSemaphoreCreateCounting(uxMaxCount, uxInitialCount)   xQueueCreateCountingSemaphore( ( uxMaxCount ), ( uxInitialCount ) )
#define	xSemaphoreCreateMutex()   xQueueCreateMutex( queueQUEUE_TYPE_MUTEX )
#define	xSemaphoreCreateRecursiveMutex()   xQueueCreateMutex( queueQUEUE_TYPE_RECURSIVE_MUTEX )
#define	xSemaphoreGetMutexHolder(xSemaphore)   xQueueGetMutexHolder( ( xSemaphore ) )
	semphr.h More...
#define	xSemaphoreGive(xSemaphore)   xQueueGenericSend( ( xQueueHandle ) ( xSemaphore ), NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )
#define	xSemaphoreGiveFromISR(xSemaphore, pxHigherPriorityTaskWoken)   xQueueGenericSendFromISR( ( xQueueHandle ) ( xSemaphore ), NULL, ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )
#define	xSemaphoreGiveRecursive(xMutex)   xQueueGiveMutexRecursive( ( xMutex ) )
#define	xSemaphoreTake(xSemaphore, xBlockTime)   xQueueGenericReceive( ( xQueueHandle ) ( xSemaphore ), NULL, ( xBlockTime ), pdFALSE )
#define	xSemaphoreTakeFromISR(xSemaphore, pxHigherPriorityTaskWoken)   xQueueReceiveFromISR( ( xQueueHandle ) ( xSemaphore ), NULL, ( pxHigherPriorityTaskWoken ) )
	semphr. More...
#define	xSemaphoreTakeRecursive(xMutex, xBlockTime)   xQueueTakeMutexRecursive( ( xMutex ), ( xBlockTime ) )

Typedefs
typedef xQueueHandle	xSemaphoreHandle

#define semBINARY_SEMAPHORE_QUEUE_LENGTH   ( ( unsigned char ) 1U )

#define semGIVE_BLOCK_TIME   ( ( portTickType ) 0U )

#define semSEMAPHORE_QUEUE_ITEM_LENGTH   ( ( unsigned char ) 0U )

#define vSemaphoreCreateBinary

(

xSemaphore

)

Value:

{                                                                                                                                           \
        ( xSemaphore ) = xQueueGenericCreate( ( unsigned portBASE_TYPE ) 1, semSEMAPHORE_QUEUE_ITEM_LENGTH, queueQUEUE_TYPE_BINARY_SEMAPHORE ); \
        if( ( xSemaphore ) != NULL )                                                                                                            \
        {                                                                                                                                       \
			xSemaphoreGive( ( xSemaphore ) );                                                                                                    \
        }                                                                                                                                       \
    }

#define vSemaphoreDelete

(

xSemaphore

)

vQueueDelete( ( xQueueHandle ) ( xSemaphore ) )

#define xSemaphoreAltGive

(

xSemaphore

)

xQueueAltGenericSend( ( xQueueHandle ) ( xSemaphore ), NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )

#define xSemaphoreAltTake	(		xSemaphore,
			xBlockTime
	)		xQueueAltGenericReceive( ( xQueueHandle ) ( xSemaphore ), NULL, ( xBlockTime ), pdFALSE )

#define xSemaphoreCreateCounting	(		uxMaxCount,
			uxInitialCount
	)		xQueueCreateCountingSemaphore( ( uxMaxCount ), ( uxInitialCount ) )

#define xSemaphoreCreateMutex

(

)

xQueueCreateMutex( queueQUEUE_TYPE_MUTEX )

#define xSemaphoreCreateRecursiveMutex

(

)

xQueueCreateMutex( queueQUEUE_TYPE_RECURSIVE_MUTEX )

#define xSemaphoreGetMutexHolder

(

xSemaphore

)

xQueueGetMutexHolder( ( xSemaphore ) )

semphr.h

xTaskHandle xSemaphoreGetMutexHolder( xSemaphoreHandle xMutex );

If xMutex is indeed a mutex type semaphore, return the current mutex holder. If xMutex is not a mutex type semaphore, or the mutex is available (not held by a task), return NULL.

Note: This Is is a good way of determining if the calling task is the mutex holder, but not a good way of determining the identity of the mutex holder as the holder may change between the function exiting and the returned value being tested.

#define xSemaphoreGive

(

xSemaphore

)

xQueueGenericSend( ( xQueueHandle ) ( xSemaphore ), NULL, semGIVE_BLOCK_TIME, queueSEND_TO_BACK )

#define xSemaphoreGiveFromISR	(		xSemaphore,
			pxHigherPriorityTaskWoken
	)		xQueueGenericSendFromISR( ( xQueueHandle ) ( xSemaphore ), NULL, ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )

#define xSemaphoreGiveRecursive

(

xMutex

)

xQueueGiveMutexRecursive( ( xMutex ) )

#define xSemaphoreTake	(		xSemaphore,
			xBlockTime
	)		xQueueGenericReceive( ( xQueueHandle ) ( xSemaphore ), NULL, ( xBlockTime ), pdFALSE )

#define xSemaphoreTakeFromISR	(		xSemaphore,
			pxHigherPriorityTaskWoken
	)		xQueueReceiveFromISR( ( xQueueHandle ) ( xSemaphore ), NULL, ( pxHigherPriorityTaskWoken ) )

semphr.

h

xSemaphoreTakeFromISR( 
                         xSemaphoreHandle xSemaphore, 
                         signed portBASE_TYPE *pxHigherPriorityTaskWoken
                     )

Macro to take a semaphore from an ISR. The semaphore must have previously been created with a call to vSemaphoreCreateBinary() or xSemaphoreCreateCounting().

Mutex type semaphores (those created using a call to xSemaphoreCreateMutex()) must not be used with this macro.

This macro can be used from an ISR, however taking a semaphore from an ISR is not a common operation. It is likely to only be useful when taking a counting semaphore when an interrupt is obtaining an object from a resource pool (when the semaphore count indicates the number of resources available).

Parameters

xSemaphore	A handle to the semaphore being taken. This is the handle returned when the semaphore was created.
pxHigherPriorityTaskWoken	xSemaphoreTakeFromISR() will set *pxHigherPriorityTaskWoken to pdTRUE if taking the semaphore caused a task to unblock, and the unblocked task has a priority higher than the currently running task. If xSemaphoreTakeFromISR() sets this value to pdTRUE then a context switch should be requested before the interrupt is exited.

Returns

pdTRUE if the semaphore was successfully taken, otherwise pdFALSE

#define xSemaphoreTakeRecursive	(		xMutex,
			xBlockTime
	)		xQueueTakeMutexRecursive( ( xMutex ), ( xBlockTime ) )

typedef xQueueHandle xSemaphoreHandle