The Queue class represents a collection of objects that are stored first by order of priority, and then in first-in, first-out (FIFO) order. More...

#include <Queue.h>

Inheritance diagram for Queue< T, queue_sz >:

Public Member Functions
	Queue ()
	Create and initialize a message Queue of objects of the parameterized type `T` and maximum capacity specified by `queue_sz`. More...

	~Queue ()
	Queue destructor. More...

bool	empty () const
	Check if the queue is empty. More...

bool	full () const
	Check if the queue is full. More...

uint32_t	count () const
	Get number of queued messages in the queue. More...

osStatus	put (T *data, uint32_t millisec=0, uint8_t prio=0)
	Inserts the given element to the end of the queue. More...

osEvent	get (uint32_t millisec=osWaitForever)
	Get a message or wait for a message from the queue. More...

Detailed Description

template<typename T, uint32_t queue_sz>
class rtos::Queue< T, queue_sz >

The Queue class represents a collection of objects that are stored first by order of priority, and then in first-in, first-out (FIFO) order.

You can use a queue when you need to store data and then access it in the same order that it has been stored. The order in which you retrieve the data is in order of descending priority. If multiple elements have the same priority, they are retrieved in FIFO order.

The object type stored in the queue can be an integer, pointer or a generic type given by the template parameter T.

Template Parameters

T	Specifies the type of elements stored in the queue.
queue_sz	Maximum number of messages that you can store in the queue.

Note: Memory considerations: The queue control structures are created on the current thread's stack, both for the Mbed OS and underlying RTOS objects (static or dynamic RTOS memory pools are not being used).

Definition at line 62 of file Queue.h.

Constructor & Destructor Documentation

Queue ( )

Create and initialize a message Queue of objects of the parameterized type T and maximum capacity specified by queue_sz.

Note: You cannot call this function from ISR context.

Definition at line 69 of file Queue.h.

~Queue ( )

Queue destructor.

Note: You cannot call this function from ISR context.

Definition at line 84 of file Queue.h.

Member Function Documentation

uint32_t count ( ) const

Get number of queued messages in the queue.

Returns: Number of items in the queue

Note: You may call this function from ISR context.

Definition at line 117 of file Queue.h.

bool empty ( ) const

Check if the queue is empty.

Returns: True if the queue is empty, false if not

Note: You may call this function from ISR context.

Definition at line 95 of file Queue.h.

bool full ( ) const

Check if the queue is full.

Returns: True if the queue is full, false if not

Note: You may call this function from ISR context.

Definition at line 106 of file Queue.h.

osEvent get ( uint32_t millisec = osWaitForever )

Get a message or wait for a message from the queue.

This function retrieves a message from the queue. The message is stored in the value field of the returned osEvent object.

The timeout specified by the parameter millisec specifies how long the function waits to retrieve the message from the queue.

The timeout parameter can have the following values:

When the timeout is 0, the function returns instantly.
When the timeout is osWaitForever (default), the function waits infinite time until the message is retrieved.
When the timeout is any other value, the function waits for the specified time before returning a timeout error.

Messages are retrieved in descending priority order. If two messages share the same priority level, they are retrieved in first-in, first-out (FIFO) order.

Parameters

millisec Timeout value. (default: osWaitForever).

Returns: Event information that includes the message in event. Message value and the status code in event.status: osEventMessage Message successfully received. osOK No message is available in the queue, and no timeout was specified. osEventTimeout No message was received before a timeout event occurred. osErrorParameter A parameter is invalid or outside of a permitted range.

Note: You may call this function from ISR context if the millisec parameter is set to 0.

Definition at line 199 of file Queue.h.

osStatus put	(	T *	data,
		uint32_t	millisec = `0`,
		uint8_t	prio = `0`
	)

Inserts the given element to the end of the queue.

This function puts the message pointed to by data into the queue. The parameter prio is used to sort the message according to their priority (higher numbers indicate higher priority) on insertion.

The timeout indicated by the parameter millisec specifies how long the function blocks waiting for the message to be inserted into the queue.

The parameter millisec can have the following values:

When the timeout is 0 (the default), the function returns instantly.
When the timeout is osWaitForever, the function waits for an infinite time.
For all other values, the function waits for the given number of milliseconds.

Parameters

data	Pointer to the element to insert into the queue.
millisec	Timeout for the operation to be executed, or 0 in case of no timeout. (default: 0)
prio	Priority of the operation or 0 in case of default. (default: 0)

Returns: Status code that indicates the execution status of the function: osOK The message has been successfully inserted into the queue. osErrorTimeout The message could not be inserted into the queue in the given time. osErrorResource The message could not be inserted because the queue is full. osErrorParameter Internal error or nonzero timeout specified in an ISR.

Note: You may call this function from ISR context if the millisec parameter is set to 0.

Definition at line 159 of file Queue.h.

Public Member Functions

Detailed Description

template<typename T, uint32_t queue_sz> class rtos::Queue< T, queue_sz >

Constructor & Destructor Documentation

Member Function Documentation

Important Information for this Arm website

template<typename T, uint32_t queue_sz>
class rtos::Queue< T, queue_sz >