2016-10-06 13:21:30 +02:00
/*
FreeRTOS V8 .2 .0 - Copyright ( C ) 2015 Real Time Engineers Ltd .
All rights reserved
VISIT http : //www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
This file is part of the FreeRTOS distribution .
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*/
# ifndef QUEUE_H
# define QUEUE_H
# ifndef INC_FREERTOS_H
# error "include FreeRTOS.h" must appear in source files before "include queue.h"
# endif
# ifdef __cplusplus
extern " C " {
# endif
/**
* Type by which queues are referenced . For example , a call to xQueueCreate ( )
* returns an QueueHandle_t variable that can then be used as a parameter to
* xQueueSend ( ) , xQueueReceive ( ) , etc .
*/
typedef void * QueueHandle_t ;
/**
* Type by which queue sets are referenced . For example , a call to
* xQueueCreateSet ( ) returns an xQueueSet variable that can then be used as a
* parameter to xQueueSelectFromSet ( ) , xQueueAddToSet ( ) , etc .
*/
typedef void * QueueSetHandle_t ;
/**
* Queue sets can contain both queues and semaphores , so the
* QueueSetMemberHandle_t is defined as a type to be used where a parameter or
* return value can be either an QueueHandle_t or an SemaphoreHandle_t .
*/
typedef void * QueueSetMemberHandle_t ;
/* For internal use only. */
# define queueSEND_TO_BACK ( ( BaseType_t ) 0 )
# define queueSEND_TO_FRONT ( ( BaseType_t ) 1 )
# define queueOVERWRITE ( ( BaseType_t ) 2 )
/* For internal use only. These definitions *must* match those in queue.c. */
# define queueQUEUE_TYPE_BASE ( ( uint8_t ) 0U )
# define queueQUEUE_TYPE_SET ( ( uint8_t ) 0U )
# define queueQUEUE_TYPE_MUTEX ( ( uint8_t ) 1U )
# define queueQUEUE_TYPE_COUNTING_SEMAPHORE ( ( uint8_t ) 2U )
# define queueQUEUE_TYPE_BINARY_SEMAPHORE ( ( uint8_t ) 3U )
# define queueQUEUE_TYPE_RECURSIVE_MUTEX ( ( uint8_t ) 4U )
/**
* queue . h
* < pre >
QueueHandle_t xQueueCreate (
UBaseType_t uxQueueLength ,
UBaseType_t uxItemSize
) ;
* < / pre >
*
* Creates a new queue instance . This allocates the storage required by the
* new queue and returns a handle for the queue .
*
* @ param uxQueueLength The maximum number of items that the queue can contain .
*
* @ param uxItemSize The number of bytes each item in the queue will require .
* Items are queued by copy , not by reference , so this is the number of bytes
* that will be copied for each posted item . Each item on the queue must be
* the same size .
*
* @ return If the queue is successfully create then a handle to the newly
* created queue is returned . If the queue cannot be created then 0 is
* returned .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} ;
void vATask ( void * pvParameters )
{
QueueHandle_t xQueue1 , xQueue2 ;
// Create a queue capable of containing 10 uint32_t values.
xQueue1 = xQueueCreate ( 10 , sizeof ( uint32_t ) ) ;
if ( xQueue1 = = 0 )
{
// Queue was not created and must not be used.
}
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue2 = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
if ( xQueue2 = = 0 )
{
// Queue was not created and must not be used.
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueCreate xQueueCreate
* \ ingroup QueueManagement
*/
2016-10-28 00:53:02 +02:00
# if( configSUPPORT_DYNAMIC_ALLOCATION == 1 )
# define xQueueCreate( uxQueueLength, uxItemSize ) xQueueGenericCreate( ( uxQueueLength ), ( uxItemSize ), ( queueQUEUE_TYPE_BASE ) )
# endif
/**
* queue . h
* < pre >
QueueHandle_t xQueueCreateStatic (
UBaseType_t uxQueueLength ,
UBaseType_t uxItemSize ,
uint8_t * pucQueueStorageBuffer ,
StaticQueue_t * pxQueueBuffer
) ;
* < / pre >
*
* Creates a new queue instance , and returns a handle by which the new queue
* can be referenced .
*
* Internally , within the FreeRTOS implementation , queues use two blocks of
* memory . The first block is used to hold the queue ' s data structures . The
* second block is used to hold items placed into the queue . If a queue is
* created using xQueueCreate ( ) then both blocks of memory are automatically
* dynamically allocated inside the xQueueCreate ( ) function . ( see
* http : //www.freertos.org/a00111.html). If a queue is created using
* xQueueCreateStatic ( ) then the application writer must provide the memory that
* will get used by the queue . xQueueCreateStatic ( ) therefore allows a queue to
* be created without using any dynamic memory allocation .
*
* http : //www.FreeRTOS.org/Embedded-RTOS-Queues.html
*
* @ param uxQueueLength The maximum number of items that the queue can contain .
*
* @ param uxItemSize The number of bytes each item in the queue will require .
* Items are queued by copy , not by reference , so this is the number of bytes
* that will be copied for each posted item . Each item on the queue must be
* the same size .
*
* @ param pucQueueStorageBuffer If uxItemSize is not zero then
* pucQueueStorageBuffer must point to a uint8_t array that is at least large
* enough to hold the maximum number of items that can be in the queue at any
* one time - which is ( uxQueueLength * uxItemsSize ) bytes . If uxItemSize is
* zero then pucQueueStorageBuffer can be NULL .
*
* @ param pxQueueBuffer Must point to a variable of type StaticQueue_t , which
* will be used to hold the queue ' s data structure .
*
* @ return If the queue is created then a handle to the created queue is
* returned . If pxQueueBuffer is NULL then NULL is returned .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} ;
# define QUEUE_LENGTH 10
# define ITEM_SIZE sizeof( uint32_t )
// xQueueBuffer will hold the queue structure.
StaticQueue_t xQueueBuffer ;
// ucQueueStorage will hold the items posted to the queue. Must be at least
// [(queue length) * ( queue item size)] bytes long.
uint8_t ucQueueStorage [ QUEUE_LENGTH * ITEM_SIZE ] ;
void vATask ( void * pvParameters )
{
QueueHandle_t xQueue1 ;
// Create a queue capable of containing 10 uint32_t values.
xQueue1 = xQueueCreate ( QUEUE_LENGTH , // The number of items the queue can hold.
ITEM_SIZE // The size of each item in the queue
& ( ucQueueStorage [ 0 ] ) , // The buffer that will hold the items in the queue.
& xQueueBuffer ) ; // The buffer that will hold the queue structure.
// The queue is guaranteed to be created successfully as no dynamic memory
// allocation is used. Therefore xQueue1 is now a handle to a valid queue.
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueCreateStatic xQueueCreateStatic
* \ ingroup QueueManagement
*/
# if( configSUPPORT_STATIC_ALLOCATION == 1 )
# define xQueueCreateStatic( uxQueueLength, uxItemSize, pucQueueStorage, pxQueueBuffer ) xQueueGenericCreateStatic( ( uxQueueLength ), ( uxItemSize ), ( pucQueueStorage ), ( pxQueueBuffer ), ( queueQUEUE_TYPE_BASE ) )
# endif /* configSUPPORT_STATIC_ALLOCATION */
2016-10-06 13:21:30 +02:00
/**
* queue . h
* < pre >
BaseType_t xQueueSendToToFront (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
TickType_t xTicksToWait
) ;
* < / pre >
*
* This is a macro that calls xQueueGenericSend ( ) .
*
* Post an item to the front of a queue . The item is queued by copy , not by
* reference . This function must not be called from an interrupt service
* routine . See xQueueSendFromISR ( ) for an alternative which may be used
* in an ISR .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param xTicksToWait The maximum amount of time the task should block
* waiting for space to become available on the queue , should it already
* be full . The call will return immediately if this is set to 0 and the
* queue is full . The time is defined in tick periods so the constant
* portTICK_PERIOD_MS should be used to convert to real time if this is required .
*
* @ return pdTRUE if the item was successfully posted , otherwise errQUEUE_FULL .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} xMessage ;
uint32_t ulVar = 10UL ;
void vATask ( void * pvParameters )
{
QueueHandle_t xQueue1 , xQueue2 ;
struct AMessage * pxMessage ;
// Create a queue capable of containing 10 uint32_t values.
xQueue1 = xQueueCreate ( 10 , sizeof ( uint32_t ) ) ;
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue2 = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
// ...
if ( xQueue1 ! = 0 )
{
// Send an uint32_t. Wait for 10 ticks for space to become
// available if necessary.
if ( xQueueSendToFront ( xQueue1 , ( void * ) & ulVar , ( TickType_t ) 10 ) ! = pdPASS )
{
// Failed to post the message, even after 10 ticks.
}
}
if ( xQueue2 ! = 0 )
{
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage ;
xQueueSendToFront ( xQueue2 , ( void * ) & pxMessage , ( TickType_t ) 0 ) ;
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueSend xQueueSend
* \ ingroup QueueManagement
*/
# define xQueueSendToFront( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_FRONT )
/**
* queue . h
* < pre >
BaseType_t xQueueSendToBack (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
TickType_t xTicksToWait
) ;
* < / pre >
*
* This is a macro that calls xQueueGenericSend ( ) .
*
* Post an item to the back of a queue . The item is queued by copy , not by
* reference . This function must not be called from an interrupt service
* routine . See xQueueSendFromISR ( ) for an alternative which may be used
* in an ISR .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param xTicksToWait The maximum amount of time the task should block
* waiting for space to become available on the queue , should it already
* be full . The call will return immediately if this is set to 0 and the queue
* is full . The time is defined in tick periods so the constant
* portTICK_PERIOD_MS should be used to convert to real time if this is required .
*
* @ return pdTRUE if the item was successfully posted , otherwise errQUEUE_FULL .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} xMessage ;
uint32_t ulVar = 10UL ;
void vATask ( void * pvParameters )
{
QueueHandle_t xQueue1 , xQueue2 ;
struct AMessage * pxMessage ;
// Create a queue capable of containing 10 uint32_t values.
xQueue1 = xQueueCreate ( 10 , sizeof ( uint32_t ) ) ;
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue2 = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
// ...
if ( xQueue1 ! = 0 )
{
// Send an uint32_t. Wait for 10 ticks for space to become
// available if necessary.
if ( xQueueSendToBack ( xQueue1 , ( void * ) & ulVar , ( TickType_t ) 10 ) ! = pdPASS )
{
// Failed to post the message, even after 10 ticks.
}
}
if ( xQueue2 ! = 0 )
{
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage ;
xQueueSendToBack ( xQueue2 , ( void * ) & pxMessage , ( TickType_t ) 0 ) ;
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueSend xQueueSend
* \ ingroup QueueManagement
*/
# define xQueueSendToBack( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )
/**
* queue . h
* < pre >
BaseType_t xQueueSend (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
TickType_t xTicksToWait
) ;
* < / pre >
*
* This is a macro that calls xQueueGenericSend ( ) . It is included for
* backward compatibility with versions of FreeRTOS . org that did not
* include the xQueueSendToFront ( ) and xQueueSendToBack ( ) macros . It is
* equivalent to xQueueSendToBack ( ) .
*
* Post an item on a queue . The item is queued by copy , not by reference .
* This function must not be called from an interrupt service routine .
* See xQueueSendFromISR ( ) for an alternative which may be used in an ISR .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param xTicksToWait The maximum amount of time the task should block
* waiting for space to become available on the queue , should it already
* be full . The call will return immediately if this is set to 0 and the
* queue is full . The time is defined in tick periods so the constant
* portTICK_PERIOD_MS should be used to convert to real time if this is required .
*
* @ return pdTRUE if the item was successfully posted , otherwise errQUEUE_FULL .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} xMessage ;
uint32_t ulVar = 10UL ;
void vATask ( void * pvParameters )
{
QueueHandle_t xQueue1 , xQueue2 ;
struct AMessage * pxMessage ;
// Create a queue capable of containing 10 uint32_t values.
xQueue1 = xQueueCreate ( 10 , sizeof ( uint32_t ) ) ;
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue2 = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
// ...
if ( xQueue1 ! = 0 )
{
// Send an uint32_t. Wait for 10 ticks for space to become
// available if necessary.
if ( xQueueSend ( xQueue1 , ( void * ) & ulVar , ( TickType_t ) 10 ) ! = pdPASS )
{
// Failed to post the message, even after 10 ticks.
}
}
if ( xQueue2 ! = 0 )
{
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage ;
xQueueSend ( xQueue2 , ( void * ) & pxMessage , ( TickType_t ) 0 ) ;
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueSend xQueueSend
* \ ingroup QueueManagement
*/
# define xQueueSend( xQueue, pvItemToQueue, xTicksToWait ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )
/**
* queue . h
* < pre >
BaseType_t xQueueOverwrite (
QueueHandle_t xQueue ,
const void * pvItemToQueue
) ;
* < / pre >
*
* Only for use with queues that have a length of one - so the queue is either
* empty or full .
*
* Post an item on a queue . If the queue is already full then overwrite the
* value held in the queue . The item is queued by copy , not by reference .
*
* This function must not be called from an interrupt service routine .
* See xQueueOverwriteFromISR ( ) for an alternative which may be used in an ISR .
*
* @ param xQueue The handle of the queue to which the data is being sent .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ return xQueueOverwrite ( ) is a macro that calls xQueueGenericSend ( ) , and
* therefore has the same return values as xQueueSendToFront ( ) . However , pdPASS
* is the only value that can be returned because xQueueOverwrite ( ) will write
* to the queue even when the queue is already full .
*
* Example usage :
< pre >
void vFunction ( void * pvParameters )
{
QueueHandle_t xQueue ;
uint32_t ulVarToSend , ulValReceived ;
// Create a queue to hold one uint32_t value. It is strongly
// recommended *not* to use xQueueOverwrite() on queues that can
// contain more than one value, and doing so will trigger an assertion
// if configASSERT() is defined.
xQueue = xQueueCreate ( 1 , sizeof ( uint32_t ) ) ;
// Write the value 10 to the queue using xQueueOverwrite().
ulVarToSend = 10 ;
xQueueOverwrite ( xQueue , & ulVarToSend ) ;
// Peeking the queue should now return 10, but leave the value 10 in
// the queue. A block time of zero is used as it is known that the
// queue holds a value.
ulValReceived = 0 ;
xQueuePeek ( xQueue , & ulValReceived , 0 ) ;
if ( ulValReceived ! = 10 )
{
// Error unless the item was removed by a different task.
}
// The queue is still full. Use xQueueOverwrite() to overwrite the
// value held in the queue with 100.
ulVarToSend = 100 ;
xQueueOverwrite ( xQueue , & ulVarToSend ) ;
// This time read from the queue, leaving the queue empty once more.
// A block time of 0 is used again.
xQueueReceive ( xQueue , & ulValReceived , 0 ) ;
// The value read should be the last value written, even though the
// queue was already full when the value was written.
if ( ulValReceived ! = 100 )
{
// Error!
}
// ...
}
< / pre >
* \ defgroup xQueueOverwrite xQueueOverwrite
* \ ingroup QueueManagement
*/
# define xQueueOverwrite( xQueue, pvItemToQueue ) xQueueGenericSend( ( xQueue ), ( pvItemToQueue ), 0, queueOVERWRITE )
/**
* queue . h
* < pre >
BaseType_t xQueueGenericSend (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
TickType_t xTicksToWait
BaseType_t xCopyPosition
) ;
* < / pre >
*
* It is preferred that the macros xQueueSend ( ) , xQueueSendToFront ( ) and
* xQueueSendToBack ( ) are used in place of calling this function directly .
*
* Post an item on a queue . The item is queued by copy , not by reference .
* This function must not be called from an interrupt service routine .
* See xQueueSendFromISR ( ) for an alternative which may be used in an ISR .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param xTicksToWait The maximum amount of time the task should block
* waiting for space to become available on the queue , should it already
* be full . The call will return immediately if this is set to 0 and the
* queue is full . The time is defined in tick periods so the constant
* portTICK_PERIOD_MS should be used to convert to real time if this is required .
*
* @ param xCopyPosition Can take the value queueSEND_TO_BACK to place the
* item at the back of the queue , or queueSEND_TO_FRONT to place the item
* at the front of the queue ( for high priority messages ) .
*
* @ return pdTRUE if the item was successfully posted , otherwise errQUEUE_FULL .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} xMessage ;
uint32_t ulVar = 10UL ;
void vATask ( void * pvParameters )
{
QueueHandle_t xQueue1 , xQueue2 ;
struct AMessage * pxMessage ;
// Create a queue capable of containing 10 uint32_t values.
xQueue1 = xQueueCreate ( 10 , sizeof ( uint32_t ) ) ;
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue2 = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
// ...
if ( xQueue1 ! = 0 )
{
// Send an uint32_t. Wait for 10 ticks for space to become
// available if necessary.
if ( xQueueGenericSend ( xQueue1 , ( void * ) & ulVar , ( TickType_t ) 10 , queueSEND_TO_BACK ) ! = pdPASS )
{
// Failed to post the message, even after 10 ticks.
}
}
if ( xQueue2 ! = 0 )
{
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage ;
xQueueGenericSend ( xQueue2 , ( void * ) & pxMessage , ( TickType_t ) 0 , queueSEND_TO_BACK ) ;
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueSend xQueueSend
* \ ingroup QueueManagement
*/
BaseType_t xQueueGenericSend ( QueueHandle_t xQueue , const void * const pvItemToQueue , TickType_t xTicksToWait , const BaseType_t xCopyPosition ) PRIVILEGED_FUNCTION ;
/**
* queue . h
* < pre >
BaseType_t xQueuePeek (
QueueHandle_t xQueue ,
void * pvBuffer ,
TickType_t xTicksToWait
) ; < / pre >
*
* This is a macro that calls the xQueueGenericReceive ( ) function .
*
* Receive an item from a queue without removing the item from the queue .
* The item is received by copy so a buffer of adequate size must be
* provided . The number of bytes copied into the buffer was defined when
* the queue was created .
*
* Successfully received items remain on the queue so will be returned again
* by the next call , or a call to xQueueReceive ( ) .
*
* This macro must not be used in an interrupt service routine . See
* xQueuePeekFromISR ( ) for an alternative that can be called from an interrupt
* service routine .
*
* @ param xQueue The handle to the queue from which the item is to be
* received .
*
* @ param pvBuffer Pointer to the buffer into which the received item will
* be copied .
*
* @ param xTicksToWait The maximum amount of time the task should block
* waiting for an item to receive should the queue be empty at the time
* of the call . The time is defined in tick periods so the constant
* portTICK_PERIOD_MS should be used to convert to real time if this is required .
* xQueuePeek ( ) will return immediately if xTicksToWait is 0 and the queue
* is empty .
*
* @ return pdTRUE if an item was successfully received from the queue ,
* otherwise pdFALSE .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} xMessage ;
QueueHandle_t xQueue ;
// Task to create a queue and post a value.
void vATask ( void * pvParameters )
{
struct AMessage * pxMessage ;
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
if ( xQueue = = 0 )
{
// Failed to create the queue.
}
// ...
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage ;
xQueueSend ( xQueue , ( void * ) & pxMessage , ( TickType_t ) 0 ) ;
// ... Rest of task code.
}
// Task to peek the data from the queue.
void vADifferentTask ( void * pvParameters )
{
struct AMessage * pxRxedMessage ;
if ( xQueue ! = 0 )
{
// Peek a message on the created queue. Block for 10 ticks if a
// message is not immediately available.
if ( xQueuePeek ( xQueue , & ( pxRxedMessage ) , ( TickType_t ) 10 ) )
{
// pcRxedMessage now points to the struct AMessage variable posted
// by vATask, but the item still remains on the queue.
}
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueReceive xQueueReceive
* \ ingroup QueueManagement
*/
# define xQueuePeek( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdTRUE )
/**
* queue . h
* < pre >
BaseType_t xQueuePeekFromISR (
QueueHandle_t xQueue ,
void * pvBuffer ,
) ; < / pre >
*
* A version of xQueuePeek ( ) that can be called from an interrupt service
* routine ( ISR ) .
*
* Receive an item from a queue without removing the item from the queue .
* The item is received by copy so a buffer of adequate size must be
* provided . The number of bytes copied into the buffer was defined when
* the queue was created .
*
* Successfully received items remain on the queue so will be returned again
* by the next call , or a call to xQueueReceive ( ) .
*
* @ param xQueue The handle to the queue from which the item is to be
* received .
*
* @ param pvBuffer Pointer to the buffer into which the received item will
* be copied .
*
* @ return pdTRUE if an item was successfully received from the queue ,
* otherwise pdFALSE .
*
* \ defgroup xQueuePeekFromISR xQueuePeekFromISR
* \ ingroup QueueManagement
*/
BaseType_t xQueuePeekFromISR ( QueueHandle_t xQueue , void * const pvBuffer ) PRIVILEGED_FUNCTION ;
/**
* queue . h
* < pre >
BaseType_t xQueueReceive (
QueueHandle_t xQueue ,
void * pvBuffer ,
TickType_t xTicksToWait
) ; < / pre >
*
* This is a macro that calls the xQueueGenericReceive ( ) function .
*
* Receive an item from a queue . The item is received by copy so a buffer of
* adequate size must be provided . The number of bytes copied into the buffer
* was defined when the queue was created .
*
* Successfully received items are removed from the queue .
*
* This function must not be used in an interrupt service routine . See
* xQueueReceiveFromISR for an alternative that can .
*
* @ param xQueue The handle to the queue from which the item is to be
* received .
*
* @ param pvBuffer Pointer to the buffer into which the received item will
* be copied .
*
* @ param xTicksToWait The maximum amount of time the task should block
* waiting for an item to receive should the queue be empty at the time
* of the call . xQueueReceive ( ) will return immediately if xTicksToWait
* is zero and the queue is empty . The time is defined in tick periods so the
* constant portTICK_PERIOD_MS should be used to convert to real time if this is
* required .
*
* @ return pdTRUE if an item was successfully received from the queue ,
* otherwise pdFALSE .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} xMessage ;
QueueHandle_t xQueue ;
// Task to create a queue and post a value.
void vATask ( void * pvParameters )
{
struct AMessage * pxMessage ;
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
if ( xQueue = = 0 )
{
// Failed to create the queue.
}
// ...
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage ;
xQueueSend ( xQueue , ( void * ) & pxMessage , ( TickType_t ) 0 ) ;
// ... Rest of task code.
}
// Task to receive from the queue.
void vADifferentTask ( void * pvParameters )
{
struct AMessage * pxRxedMessage ;
if ( xQueue ! = 0 )
{
// Receive a message on the created queue. Block for 10 ticks if a
// message is not immediately available.
if ( xQueueReceive ( xQueue , & ( pxRxedMessage ) , ( TickType_t ) 10 ) )
{
// pcRxedMessage now points to the struct AMessage variable posted
// by vATask.
}
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueReceive xQueueReceive
* \ ingroup QueueManagement
*/
# define xQueueReceive( xQueue, pvBuffer, xTicksToWait ) xQueueGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdFALSE )
/**
* queue . h
* < pre >
BaseType_t xQueueGenericReceive (
QueueHandle_t xQueue ,
void * pvBuffer ,
TickType_t xTicksToWait
BaseType_t xJustPeek
) ; < / pre >
*
* It is preferred that the macro xQueueReceive ( ) be used rather than calling
* this function directly .
*
* Receive an item from a queue . The item is received by copy so a buffer of
* adequate size must be provided . The number of bytes copied into the buffer
* was defined when the queue was created .
*
* This function must not be used in an interrupt service routine . See
* xQueueReceiveFromISR for an alternative that can .
*
* @ param xQueue The handle to the queue from which the item is to be
* received .
*
* @ param pvBuffer Pointer to the buffer into which the received item will
* be copied .
*
* @ param xTicksToWait The maximum amount of time the task should block
* waiting for an item to receive should the queue be empty at the time
* of the call . The time is defined in tick periods so the constant
* portTICK_PERIOD_MS should be used to convert to real time if this is required .
* xQueueGenericReceive ( ) will return immediately if the queue is empty and
* xTicksToWait is 0.
*
* @ param xJustPeek When set to true , the item received from the queue is not
* actually removed from the queue - meaning a subsequent call to
* xQueueReceive ( ) will return the same item . When set to false , the item
* being received from the queue is also removed from the queue .
*
* @ return pdTRUE if an item was successfully received from the queue ,
* otherwise pdFALSE .
*
* Example usage :
< pre >
struct AMessage
{
char ucMessageID ;
char ucData [ 20 ] ;
} xMessage ;
QueueHandle_t xQueue ;
// Task to create a queue and post a value.
void vATask ( void * pvParameters )
{
struct AMessage * pxMessage ;
// Create a queue capable of containing 10 pointers to AMessage structures.
// These should be passed by pointer as they contain a lot of data.
xQueue = xQueueCreate ( 10 , sizeof ( struct AMessage * ) ) ;
if ( xQueue = = 0 )
{
// Failed to create the queue.
}
// ...
// Send a pointer to a struct AMessage object. Don't block if the
// queue is already full.
pxMessage = & xMessage ;
xQueueSend ( xQueue , ( void * ) & pxMessage , ( TickType_t ) 0 ) ;
// ... Rest of task code.
}
// Task to receive from the queue.
void vADifferentTask ( void * pvParameters )
{
struct AMessage * pxRxedMessage ;
if ( xQueue ! = 0 )
{
// Receive a message on the created queue. Block for 10 ticks if a
// message is not immediately available.
if ( xQueueGenericReceive ( xQueue , & ( pxRxedMessage ) , ( TickType_t ) 10 ) )
{
// pcRxedMessage now points to the struct AMessage variable posted
// by vATask.
}
}
// ... Rest of task code.
}
< / pre >
* \ defgroup xQueueReceive xQueueReceive
* \ ingroup QueueManagement
*/
BaseType_t xQueueGenericReceive ( QueueHandle_t xQueue , void * const pvBuffer , TickType_t xTicksToWait , const BaseType_t xJustPeek ) PRIVILEGED_FUNCTION ;
/**
* queue . h
* < pre > UBaseType_t uxQueueMessagesWaiting ( const QueueHandle_t xQueue ) ; < / pre >
*
* Return the number of messages stored in a queue .
*
* @ param xQueue A handle to the queue being queried .
*
* @ return The number of messages available in the queue .
*
* \ defgroup uxQueueMessagesWaiting uxQueueMessagesWaiting
* \ ingroup QueueManagement
*/
UBaseType_t uxQueueMessagesWaiting ( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
/**
* queue . h
* < pre > UBaseType_t uxQueueSpacesAvailable ( const QueueHandle_t xQueue ) ; < / pre >
*
* Return the number of free spaces available in a queue . This is equal to the
* number of items that can be sent to the queue before the queue becomes full
* if no items are removed .
*
* @ param xQueue A handle to the queue being queried .
*
* @ return The number of spaces available in the queue .
*
* \ defgroup uxQueueMessagesWaiting uxQueueMessagesWaiting
* \ ingroup QueueManagement
*/
UBaseType_t uxQueueSpacesAvailable ( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
/**
* queue . h
* < pre > void vQueueDelete ( QueueHandle_t xQueue ) ; < / pre >
*
* Delete a queue - freeing all the memory allocated for storing of items
* placed on the queue .
*
* @ param xQueue A handle to the queue to be deleted .
*
* \ defgroup vQueueDelete vQueueDelete
* \ ingroup QueueManagement
*/
void vQueueDelete ( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
/**
* queue . h
* < pre >
BaseType_t xQueueSendToFrontFromISR (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
BaseType_t * pxHigherPriorityTaskWoken
) ;
< / pre >
*
* This is a macro that calls xQueueGenericSendFromISR ( ) .
*
* Post an item to the front of a queue . It is safe to use this macro from
* within an interrupt service routine .
*
* Items are queued by copy not reference so it is preferable to only
* queue small items , especially when called from an ISR . In most cases
* it would be preferable to store a pointer to the item being queued .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param pxHigherPriorityTaskWoken xQueueSendToFrontFromISR ( ) will set
* * pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
* to unblock , and the unblocked task has a priority higher than the currently
* running task . If xQueueSendToFromFromISR ( ) sets this value to pdTRUE then
* a context switch should be requested before the interrupt is exited .
*
* @ return pdTRUE if the data was successfully sent to the queue , otherwise
* errQUEUE_FULL .
*
* Example usage for buffered IO ( where the ISR can obtain more than one value
* per call ) :
< pre >
void vBufferISR ( void )
{
char cIn ;
BaseType_t xHigherPrioritTaskWoken ;
// We have not woken a task at the start of the ISR.
xHigherPriorityTaskWoken = pdFALSE ;
// Loop until the buffer is empty.
do
{
// Obtain a byte from the buffer.
cIn = portINPUT_BYTE ( RX_REGISTER_ADDRESS ) ;
// Post the byte.
xQueueSendToFrontFromISR ( xRxQueue , & cIn , & xHigherPriorityTaskWoken ) ;
} while ( portINPUT_BYTE ( BUFFER_COUNT ) ) ;
// Now the buffer is empty we can switch context if necessary.
if ( xHigherPriorityTaskWoken )
{
taskYIELD ( ) ;
}
}
< / pre >
*
* \ defgroup xQueueSendFromISR xQueueSendFromISR
* \ ingroup QueueManagement
*/
# define xQueueSendToFrontFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_FRONT )
/**
* queue . h
* < pre >
BaseType_t xQueueSendToBackFromISR (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
BaseType_t * pxHigherPriorityTaskWoken
) ;
< / pre >
*
* This is a macro that calls xQueueGenericSendFromISR ( ) .
*
* Post an item to the back of a queue . It is safe to use this macro from
* within an interrupt service routine .
*
* Items are queued by copy not reference so it is preferable to only
* queue small items , especially when called from an ISR . In most cases
* it would be preferable to store a pointer to the item being queued .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param pxHigherPriorityTaskWoken xQueueSendToBackFromISR ( ) will set
* * pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
* to unblock , and the unblocked task has a priority higher than the currently
* running task . If xQueueSendToBackFromISR ( ) sets this value to pdTRUE then
* a context switch should be requested before the interrupt is exited .
*
* @ return pdTRUE if the data was successfully sent to the queue , otherwise
* errQUEUE_FULL .
*
* Example usage for buffered IO ( where the ISR can obtain more than one value
* per call ) :
< pre >
void vBufferISR ( void )
{
char cIn ;
BaseType_t xHigherPriorityTaskWoken ;
// We have not woken a task at the start of the ISR.
xHigherPriorityTaskWoken = pdFALSE ;
// Loop until the buffer is empty.
do
{
// Obtain a byte from the buffer.
cIn = portINPUT_BYTE ( RX_REGISTER_ADDRESS ) ;
// Post the byte.
xQueueSendToBackFromISR ( xRxQueue , & cIn , & xHigherPriorityTaskWoken ) ;
} while ( portINPUT_BYTE ( BUFFER_COUNT ) ) ;
// Now the buffer is empty we can switch context if necessary.
if ( xHigherPriorityTaskWoken )
{
taskYIELD ( ) ;
}
}
< / pre >
*
* \ defgroup xQueueSendFromISR xQueueSendFromISR
* \ ingroup QueueManagement
*/
# define xQueueSendToBackFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )
/**
* queue . h
* < pre >
BaseType_t xQueueOverwriteFromISR (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
BaseType_t * pxHigherPriorityTaskWoken
) ;
* < / pre >
*
* A version of xQueueOverwrite ( ) that can be used in an interrupt service
* routine ( ISR ) .
*
* Only for use with queues that can hold a single item - so the queue is either
* empty or full .
*
* Post an item on a queue . If the queue is already full then overwrite the
* value held in the queue . The item is queued by copy , not by reference .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param pxHigherPriorityTaskWoken xQueueOverwriteFromISR ( ) will set
* * pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
* to unblock , and the unblocked task has a priority higher than the currently
* running task . If xQueueOverwriteFromISR ( ) sets this value to pdTRUE then
* a context switch should be requested before the interrupt is exited .
*
* @ return xQueueOverwriteFromISR ( ) is a macro that calls
* xQueueGenericSendFromISR ( ) , and therefore has the same return values as
* xQueueSendToFrontFromISR ( ) . However , pdPASS is the only value that can be
* returned because xQueueOverwriteFromISR ( ) will write to the queue even when
* the queue is already full .
*
* Example usage :
< pre >
QueueHandle_t xQueue ;
void vFunction ( void * pvParameters )
{
// Create a queue to hold one uint32_t value. It is strongly
// recommended *not* to use xQueueOverwriteFromISR() on queues that can
// contain more than one value, and doing so will trigger an assertion
// if configASSERT() is defined.
xQueue = xQueueCreate ( 1 , sizeof ( uint32_t ) ) ;
}
void vAnInterruptHandler ( void )
{
// xHigherPriorityTaskWoken must be set to pdFALSE before it is used.
BaseType_t xHigherPriorityTaskWoken = pdFALSE ;
uint32_t ulVarToSend , ulValReceived ;
// Write the value 10 to the queue using xQueueOverwriteFromISR().
ulVarToSend = 10 ;
xQueueOverwriteFromISR ( xQueue , & ulVarToSend , & xHigherPriorityTaskWoken ) ;
// The queue is full, but calling xQueueOverwriteFromISR() again will still
// pass because the value held in the queue will be overwritten with the
// new value.
ulVarToSend = 100 ;
xQueueOverwriteFromISR ( xQueue , & ulVarToSend , & xHigherPriorityTaskWoken ) ;
// Reading from the queue will now return 100.
// ...
if ( xHigherPrioritytaskWoken = = pdTRUE )
{
// Writing to the queue caused a task to unblock and the unblocked task
// has a priority higher than or equal to the priority of the currently
// executing task (the task this interrupt interrupted). Perform a context
// switch so this interrupt returns directly to the unblocked task.
portYIELD_FROM_ISR ( ) ; // or portEND_SWITCHING_ISR() depending on the port.
}
}
< / pre >
* \ defgroup xQueueOverwriteFromISR xQueueOverwriteFromISR
* \ ingroup QueueManagement
*/
# define xQueueOverwriteFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueOVERWRITE )
/**
* queue . h
* < pre >
BaseType_t xQueueSendFromISR (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
BaseType_t * pxHigherPriorityTaskWoken
) ;
< / pre >
*
* This is a macro that calls xQueueGenericSendFromISR ( ) . It is included
* for backward compatibility with versions of FreeRTOS . org that did not
* include the xQueueSendToBackFromISR ( ) and xQueueSendToFrontFromISR ( )
* macros .
*
* Post an item to the back of a queue . It is safe to use this function from
* within an interrupt service routine .
*
* Items are queued by copy not reference so it is preferable to only
* queue small items , especially when called from an ISR . In most cases
* it would be preferable to store a pointer to the item being queued .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param pxHigherPriorityTaskWoken xQueueSendFromISR ( ) will set
* * pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
* to unblock , and the unblocked task has a priority higher than the currently
* running task . If xQueueSendFromISR ( ) sets this value to pdTRUE then
* a context switch should be requested before the interrupt is exited .
*
* @ return pdTRUE if the data was successfully sent to the queue , otherwise
* errQUEUE_FULL .
*
* Example usage for buffered IO ( where the ISR can obtain more than one value
* per call ) :
< pre >
void vBufferISR ( void )
{
char cIn ;
BaseType_t xHigherPriorityTaskWoken ;
// We have not woken a task at the start of the ISR.
xHigherPriorityTaskWoken = pdFALSE ;
// Loop until the buffer is empty.
do
{
// Obtain a byte from the buffer.
cIn = portINPUT_BYTE ( RX_REGISTER_ADDRESS ) ;
// Post the byte.
xQueueSendFromISR ( xRxQueue , & cIn , & xHigherPriorityTaskWoken ) ;
} while ( portINPUT_BYTE ( BUFFER_COUNT ) ) ;
// Now the buffer is empty we can switch context if necessary.
if ( xHigherPriorityTaskWoken )
{
// Actual macro used here is port specific.
portYIELD_FROM_ISR ( ) ;
}
}
< / pre >
*
* \ defgroup xQueueSendFromISR xQueueSendFromISR
* \ ingroup QueueManagement
*/
# define xQueueSendFromISR( xQueue, pvItemToQueue, pxHigherPriorityTaskWoken ) xQueueGenericSendFromISR( ( xQueue ), ( pvItemToQueue ), ( pxHigherPriorityTaskWoken ), queueSEND_TO_BACK )
/**
* queue . h
* < pre >
BaseType_t xQueueGenericSendFromISR (
QueueHandle_t xQueue ,
const void * pvItemToQueue ,
BaseType_t * pxHigherPriorityTaskWoken ,
BaseType_t xCopyPosition
) ;
< / pre >
*
* It is preferred that the macros xQueueSendFromISR ( ) ,
* xQueueSendToFrontFromISR ( ) and xQueueSendToBackFromISR ( ) be used in place
* of calling this function directly . xQueueGiveFromISR ( ) is an
* equivalent for use by semaphores that don ' t actually copy any data .
*
* Post an item on a queue . It is safe to use this function from within an
* interrupt service routine .
*
* Items are queued by copy not reference so it is preferable to only
* queue small items , especially when called from an ISR . In most cases
* it would be preferable to store a pointer to the item being queued .
*
* @ param xQueue The handle to the queue on which the item is to be posted .
*
* @ param pvItemToQueue A pointer to the item that is to be placed on the
* queue . The size of the items the queue will hold was defined when the
* queue was created , so this many bytes will be copied from pvItemToQueue
* into the queue storage area .
*
* @ param pxHigherPriorityTaskWoken xQueueGenericSendFromISR ( ) will set
* * pxHigherPriorityTaskWoken to pdTRUE if sending to the queue caused a task
* to unblock , and the unblocked task has a priority higher than the currently
* running task . If xQueueGenericSendFromISR ( ) sets this value to pdTRUE then
* a context switch should be requested before the interrupt is exited .
*
* @ param xCopyPosition Can take the value queueSEND_TO_BACK to place the
* item at the back of the queue , or queueSEND_TO_FRONT to place the item
* at the front of the queue ( for high priority messages ) .
*
* @ return pdTRUE if the data was successfully sent to the queue , otherwise
* errQUEUE_FULL .
*
* Example usage for buffered IO ( where the ISR can obtain more than one value
* per call ) :
< pre >
void vBufferISR ( void )
{
char cIn ;
BaseType_t xHigherPriorityTaskWokenByPost ;
// We have not woken a task at the start of the ISR.
xHigherPriorityTaskWokenByPost = pdFALSE ;
// Loop until the buffer is empty.
do
{
// Obtain a byte from the buffer.
cIn = portINPUT_BYTE ( RX_REGISTER_ADDRESS ) ;
// Post each byte.
xQueueGenericSendFromISR ( xRxQueue , & cIn , & xHigherPriorityTaskWokenByPost , queueSEND_TO_BACK ) ;
} while ( portINPUT_BYTE ( BUFFER_COUNT ) ) ;
// Now the buffer is empty we can switch context if necessary. Note that the
// name of the yield function required is port specific.
if ( xHigherPriorityTaskWokenByPost )
{
taskYIELD_YIELD_FROM_ISR ( ) ;
}
}
< / pre >
*
* \ defgroup xQueueSendFromISR xQueueSendFromISR
* \ ingroup QueueManagement
*/
BaseType_t xQueueGenericSendFromISR ( QueueHandle_t xQueue , const void * const pvItemToQueue , BaseType_t * const pxHigherPriorityTaskWoken , const BaseType_t xCopyPosition ) PRIVILEGED_FUNCTION ;
BaseType_t xQueueGiveFromISR ( QueueHandle_t xQueue , BaseType_t * const pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION ;
/**
* queue . h
* < pre >
BaseType_t xQueueReceiveFromISR (
QueueHandle_t xQueue ,
void * pvBuffer ,
BaseType_t * pxTaskWoken
) ;
* < / pre >
*
* Receive an item from a queue . It is safe to use this function from within an
* interrupt service routine .
*
* @ param xQueue The handle to the queue from which the item is to be
* received .
*
* @ param pvBuffer Pointer to the buffer into which the received item will
* be copied .
*
* @ param pxTaskWoken A task may be blocked waiting for space to become
* available on the queue . If xQueueReceiveFromISR causes such a task to
* unblock * pxTaskWoken will get set to pdTRUE , otherwise * pxTaskWoken will
* remain unchanged .
*
* @ return pdTRUE if an item was successfully received from the queue ,
* otherwise pdFALSE .
*
* Example usage :
< pre >
QueueHandle_t xQueue ;
// Function to create a queue and post some values.
void vAFunction ( void * pvParameters )
{
char cValueToPost ;
const TickType_t xTicksToWait = ( TickType_t ) 0xff ;
// Create a queue capable of containing 10 characters.
xQueue = xQueueCreate ( 10 , sizeof ( char ) ) ;
if ( xQueue = = 0 )
{
// Failed to create the queue.
}
// ...
// Post some characters that will be used within an ISR. If the queue
// is full then this task will block for xTicksToWait ticks.
cValueToPost = ' a ' ;
xQueueSend ( xQueue , ( void * ) & cValueToPost , xTicksToWait ) ;
cValueToPost = ' b ' ;
xQueueSend ( xQueue , ( void * ) & cValueToPost , xTicksToWait ) ;
// ... keep posting characters ... this task may block when the queue
// becomes full.
cValueToPost = ' c ' ;
xQueueSend ( xQueue , ( void * ) & cValueToPost , xTicksToWait ) ;
}
// ISR that outputs all the characters received on the queue.
void vISR_Routine ( void )
{
BaseType_t xTaskWokenByReceive = pdFALSE ;
char cRxedChar ;
while ( xQueueReceiveFromISR ( xQueue , ( void * ) & cRxedChar , & xTaskWokenByReceive ) )
{
// A character was received. Output the character now.
vOutputCharacter ( cRxedChar ) ;
// If removing the character from the queue woke the task that was
// posting onto the queue cTaskWokenByReceive will have been set to
// pdTRUE. No matter how many times this loop iterates only one
// task will be woken.
}
if ( cTaskWokenByPost ! = ( char ) pdFALSE ;
{
taskYIELD ( ) ;
}
}
< / pre >
* \ defgroup xQueueReceiveFromISR xQueueReceiveFromISR
* \ ingroup QueueManagement
*/
BaseType_t xQueueReceiveFromISR ( QueueHandle_t xQueue , void * const pvBuffer , BaseType_t * const pxHigherPriorityTaskWoken ) PRIVILEGED_FUNCTION ;
/*
* Utilities to query queues that are safe to use from an ISR . These utilities
* should be used only from witin an ISR , or within a critical section .
*/
BaseType_t xQueueIsQueueEmptyFromISR ( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
BaseType_t xQueueIsQueueFullFromISR ( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
UBaseType_t uxQueueMessagesWaitingFromISR ( const QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
/*
* xQueueAltGenericSend ( ) is an alternative version of xQueueGenericSend ( ) .
* Likewise xQueueAltGenericReceive ( ) is an alternative version of
* xQueueGenericReceive ( ) .
*
* 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 .
*/
BaseType_t xQueueAltGenericSend ( QueueHandle_t xQueue , const void * const pvItemToQueue , TickType_t xTicksToWait , BaseType_t xCopyPosition ) ;
BaseType_t xQueueAltGenericReceive ( QueueHandle_t xQueue , void * const pvBuffer , TickType_t xTicksToWait , BaseType_t xJustPeeking ) ;
# define xQueueAltSendToFront( xQueue, pvItemToQueue, xTicksToWait ) xQueueAltGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_FRONT )
# define xQueueAltSendToBack( xQueue, pvItemToQueue, xTicksToWait ) xQueueAltGenericSend( ( xQueue ), ( pvItemToQueue ), ( xTicksToWait ), queueSEND_TO_BACK )
# define xQueueAltReceive( xQueue, pvBuffer, xTicksToWait ) xQueueAltGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdFALSE )
# define xQueueAltPeek( xQueue, pvBuffer, xTicksToWait ) xQueueAltGenericReceive( ( xQueue ), ( pvBuffer ), ( xTicksToWait ), pdTRUE )
/*
* The functions defined above are for passing data to and from tasks . The
* functions below are the equivalents for passing data to and from
* co - routines .
*
* These functions are called from the co - routine macro implementation and
* should not be called directly from application code . Instead use the macro
* wrappers defined within croutine . h .
*/
BaseType_t xQueueCRSendFromISR ( QueueHandle_t xQueue , const void * pvItemToQueue , BaseType_t xCoRoutinePreviouslyWoken ) ;
BaseType_t xQueueCRReceiveFromISR ( QueueHandle_t xQueue , void * pvBuffer , BaseType_t * pxTaskWoken ) ;
BaseType_t xQueueCRSend ( QueueHandle_t xQueue , const void * pvItemToQueue , TickType_t xTicksToWait ) ;
BaseType_t xQueueCRReceive ( QueueHandle_t xQueue , void * pvBuffer , TickType_t xTicksToWait ) ;
/*
* For internal use only . Use xSemaphoreCreateMutex ( ) ,
* xSemaphoreCreateCounting ( ) or xSemaphoreGetMutexHolder ( ) instead of calling
* these functions directly .
*/
QueueHandle_t xQueueCreateMutex ( const uint8_t ucQueueType ) PRIVILEGED_FUNCTION ;
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QueueHandle_t xQueueCreateMutexStatic ( const uint8_t ucQueueType , StaticQueue_t * pxStaticQueue ) PRIVILEGED_FUNCTION ;
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QueueHandle_t xQueueCreateCountingSemaphore ( const UBaseType_t uxMaxCount , const UBaseType_t uxInitialCount ) PRIVILEGED_FUNCTION ;
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QueueHandle_t xQueueCreateCountingSemaphoreStatic ( const UBaseType_t uxMaxCount , const UBaseType_t uxInitialCount , StaticQueue_t * pxStaticQueue ) PRIVILEGED_FUNCTION ;
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void * xQueueGetMutexHolder ( QueueHandle_t xSemaphore ) PRIVILEGED_FUNCTION ;
/*
* For internal use only . Use xSemaphoreTakeMutexRecursive ( ) or
* xSemaphoreGiveMutexRecursive ( ) instead of calling these functions directly .
*/
BaseType_t xQueueTakeMutexRecursive ( QueueHandle_t xMutex , TickType_t xTicksToWait ) PRIVILEGED_FUNCTION ;
BaseType_t xQueueGiveMutexRecursive ( QueueHandle_t pxMutex ) PRIVILEGED_FUNCTION ;
/*
* Reset a queue back to its original empty state . pdPASS is returned if the
* queue is successfully reset . pdFAIL is returned if the queue could not be
* reset because there are tasks blocked on the queue waiting to either
* receive from the queue or send to the queue .
*/
# define xQueueReset( xQueue ) xQueueGenericReset( xQueue, pdFALSE )
/*
* The registry is provided as a means for kernel aware debuggers to
* locate queues , semaphores and mutexes . Call vQueueAddToRegistry ( ) add
* a queue , semaphore or mutex handle to the registry if you want the handle
* to be available to a kernel aware debugger . If you are not using a kernel
* aware debugger then this function can be ignored .
*
* configQUEUE_REGISTRY_SIZE defines the maximum number of handles the
* registry can hold . configQUEUE_REGISTRY_SIZE must be greater than 0
* within FreeRTOSConfig . h for the registry to be available . Its value
* does not effect the number of queues , semaphores and mutexes that can be
* created - just the number that the registry can hold .
*
* @ param xQueue The handle of the queue being added to the registry . This
* is the handle returned by a call to xQueueCreate ( ) . Semaphore and mutex
* handles can also be passed in here .
*
* @ param pcName The name to be associated with the handle . This is the
* name that the kernel aware debugger will display . The queue registry only
* stores a pointer to the string - so the string must be persistent ( global or
* preferably in ROM / Flash ) , not on the stack .
*/
# if configQUEUE_REGISTRY_SIZE > 0
void vQueueAddToRegistry ( QueueHandle_t xQueue , const char * pcName ) PRIVILEGED_FUNCTION ; /*lint !e971 Unqualified char types are allowed for strings and single characters only. */
# endif
/*
* The registry is provided as a means for kernel aware debuggers to
* locate queues , semaphores and mutexes . Call vQueueAddToRegistry ( ) add
* a queue , semaphore or mutex handle to the registry if you want the handle
* to be available to a kernel aware debugger , and vQueueUnregisterQueue ( ) to
* remove the queue , semaphore or mutex from the register . If you are not using
* a kernel aware debugger then this function can be ignored .
*
* @ param xQueue The handle of the queue being removed from the registry .
*/
# if configQUEUE_REGISTRY_SIZE > 0
void vQueueUnregisterQueue ( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
# endif
/*
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* Generic version of the function used to creaet a queue using dynamic memory
* allocation . This is called by other functions and macros that create other
* RTOS objects that use the queue structure as their base .
*/
# if( configSUPPORT_DYNAMIC_ALLOCATION == 1 )
QueueHandle_t xQueueGenericCreate ( const UBaseType_t uxQueueLength , const UBaseType_t uxItemSize , const uint8_t ucQueueType ) PRIVILEGED_FUNCTION ;
# endif
/*
* Generic version of the function used to creaet a queue using dynamic memory
* allocation . This is called by other functions and macros that create other
* RTOS objects that use the queue structure as their base .
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*/
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# if( configSUPPORT_STATIC_ALLOCATION == 1 )
QueueHandle_t xQueueGenericCreateStatic ( const UBaseType_t uxQueueLength , const UBaseType_t uxItemSize , uint8_t * pucQueueStorage , StaticQueue_t * pxStaticQueue , const uint8_t ucQueueType ) PRIVILEGED_FUNCTION ;
# endif
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/*
* Queue sets provide a mechanism to allow a task to block ( pend ) on a read
* operation from multiple queues or semaphores simultaneously .
*
* See FreeRTOS / Source / Demo / Common / Minimal / QueueSet . c for an example using this
* function .
*
* A queue set must be explicitly created using a call to xQueueCreateSet ( )
* before it can be used . Once created , standard FreeRTOS queues and semaphores
* can be added to the set using calls to xQueueAddToSet ( ) .
* xQueueSelectFromSet ( ) is then used to determine which , if any , of the queues
* or semaphores contained in the set is in a state where a queue read or
* semaphore take operation would be successful .
*
* Note 1 : See the documentation on http : //wwwFreeRTOS.org/RTOS-queue-sets.html
* for reasons why queue sets are very rarely needed in practice as there are
* simpler methods of blocking on multiple objects .
*
* Note 2 : Blocking on a queue set that contains a mutex will not cause the
* mutex holder to inherit the priority of the blocked task .
*
* Note 3 : An additional 4 bytes of RAM is required for each space in a every
* queue added to a queue set . Therefore counting semaphores that have a high
* maximum count value should not be added to a queue set .
*
* Note 4 : A receive ( in the case of a queue ) or take ( in the case of a
* semaphore ) operation must not be performed on a member of a queue set unless
* a call to xQueueSelectFromSet ( ) has first returned a handle to that set member .
*
* @ param uxEventQueueLength Queue sets store events that occur on
* the queues and semaphores contained in the set . uxEventQueueLength specifies
* the maximum number of events that can be queued at once . To be absolutely
* certain that events are not lost uxEventQueueLength should be set to the
* total sum of the length of the queues added to the set , where binary
* semaphores and mutexes have a length of 1 , and counting semaphores have a
* length set by their maximum count value . Examples :
* + If a queue set is to hold a queue of length 5 , another queue of length 12 ,
* and a binary semaphore , then uxEventQueueLength should be set to
* ( 5 + 12 + 1 ) , or 18.
* + If a queue set is to hold three binary semaphores then uxEventQueueLength
* should be set to ( 1 + 1 + 1 ) , or 3.
* + If a queue set is to hold a counting semaphore that has a maximum count of
* 5 , and a counting semaphore that has a maximum count of 3 , then
* uxEventQueueLength should be set to ( 5 + 3 ) , or 8.
*
* @ return If the queue set is created successfully then a handle to the created
* queue set is returned . Otherwise NULL is returned .
*/
QueueSetHandle_t xQueueCreateSet ( const UBaseType_t uxEventQueueLength ) PRIVILEGED_FUNCTION ;
/*
* Adds a queue or semaphore to a queue set that was previously created by a
* call to xQueueCreateSet ( ) .
*
* See FreeRTOS / Source / Demo / Common / Minimal / QueueSet . c for an example using this
* function .
*
* Note 1 : A receive ( in the case of a queue ) or take ( in the case of a
* semaphore ) operation must not be performed on a member of a queue set unless
* a call to xQueueSelectFromSet ( ) has first returned a handle to that set member .
*
* @ param xQueueOrSemaphore The handle of the queue or semaphore being added to
* the queue set ( cast to an QueueSetMemberHandle_t type ) .
*
* @ param xQueueSet The handle of the queue set to which the queue or semaphore
* is being added .
*
* @ return If the queue or semaphore was successfully added to the queue set
* then pdPASS is returned . If the queue could not be successfully added to the
* queue set because it is already a member of a different queue set then pdFAIL
* is returned .
*/
BaseType_t xQueueAddToSet ( QueueSetMemberHandle_t xQueueOrSemaphore , QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION ;
/*
* Removes a queue or semaphore from a queue set . A queue or semaphore can only
* be removed from a set if the queue or semaphore is empty .
*
* See FreeRTOS / Source / Demo / Common / Minimal / QueueSet . c for an example using this
* function .
*
* @ param xQueueOrSemaphore The handle of the queue or semaphore being removed
* from the queue set ( cast to an QueueSetMemberHandle_t type ) .
*
* @ param xQueueSet The handle of the queue set in which the queue or semaphore
* is included .
*
* @ return If the queue or semaphore was successfully removed from the queue set
* then pdPASS is returned . If the queue was not in the queue set , or the
* queue ( or semaphore ) was not empty , then pdFAIL is returned .
*/
BaseType_t xQueueRemoveFromSet ( QueueSetMemberHandle_t xQueueOrSemaphore , QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION ;
/*
* xQueueSelectFromSet ( ) selects from the members of a queue set a queue or
* semaphore that either contains data ( in the case of a queue ) or is available
* to take ( in the case of a semaphore ) . xQueueSelectFromSet ( ) effectively
* allows a task to block ( pend ) on a read operation on all the queues and
* semaphores in a queue set simultaneously .
*
* See FreeRTOS / Source / Demo / Common / Minimal / QueueSet . c for an example using this
* function .
*
* Note 1 : See the documentation on http : //wwwFreeRTOS.org/RTOS-queue-sets.html
* for reasons why queue sets are very rarely needed in practice as there are
* simpler methods of blocking on multiple objects .
*
* Note 2 : Blocking on a queue set that contains a mutex will not cause the
* mutex holder to inherit the priority of the blocked task .
*
* Note 3 : A receive ( in the case of a queue ) or take ( in the case of a
* semaphore ) operation must not be performed on a member of a queue set unless
* a call to xQueueSelectFromSet ( ) has first returned a handle to that set member .
*
* @ param xQueueSet The queue set on which the task will ( potentially ) block .
*
* @ param xTicksToWait The maximum time , in ticks , that the calling task will
* remain in the Blocked state ( with other tasks executing ) to wait for a member
* of the queue set to be ready for a successful queue read or semaphore take
* operation .
*
* @ return xQueueSelectFromSet ( ) will return the handle of a queue ( cast to
* a QueueSetMemberHandle_t type ) contained in the queue set that contains data ,
* or the handle of a semaphore ( cast to a QueueSetMemberHandle_t type ) contained
* in the queue set that is available , or NULL if no such queue or semaphore
* exists before before the specified block time expires .
*/
QueueSetMemberHandle_t xQueueSelectFromSet ( QueueSetHandle_t xQueueSet , const TickType_t xTicksToWait ) PRIVILEGED_FUNCTION ;
/*
* A version of xQueueSelectFromSet ( ) that can be used from an ISR .
*/
QueueSetMemberHandle_t xQueueSelectFromSetFromISR ( QueueSetHandle_t xQueueSet ) PRIVILEGED_FUNCTION ;
/* Not public API functions. */
void vQueueWaitForMessageRestricted ( QueueHandle_t xQueue , TickType_t xTicksToWait ) PRIVILEGED_FUNCTION ;
BaseType_t xQueueGenericReset ( QueueHandle_t xQueue , BaseType_t xNewQueue ) PRIVILEGED_FUNCTION ;
void vQueueSetQueueNumber ( QueueHandle_t xQueue , UBaseType_t uxQueueNumber ) PRIVILEGED_FUNCTION ;
UBaseType_t uxQueueGetQueueNumber ( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
uint8_t ucQueueGetQueueType ( QueueHandle_t xQueue ) PRIVILEGED_FUNCTION ;
# ifdef __cplusplus
}
# endif
# endif /* QUEUE_H */
