Queues of buffer headers

Typedefs
typedef struct MMAL_QUEUE_T	MMAL_QUEUE_T
Functions
MMAL_QUEUE_T *	mmal_queue_create (void)
void	mmal_queue_put (MMAL_QUEUE_T *queue, MMAL_BUFFER_HEADER_T *buffer)
void	mmal_queue_put_back (MMAL_QUEUE_T *queue, MMAL_BUFFER_HEADER_T *buffer)
MMAL_BUFFER_HEADER_T *	mmal_queue_get (MMAL_QUEUE_T *queue)
MMAL_BUFFER_HEADER_T *	mmal_queue_wait (MMAL_QUEUE_T *queue)
unsigned int	mmal_queue_length (MMAL_QUEUE_T *queue)
void	mmal_queue_destroy (MMAL_QUEUE_T *queue)

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Detailed Description

This provides a thread-safe implementation of a queue of buffer headers (MMAL_BUFFER_HEADER_T). The queue works in a first-in, first-out basis so the buffer headers will be dequeued in the order they have been queued.

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Function Documentation

MMAL_QUEUE_T* mmal_queue_create

(

void

)

Create a queue of MMAL_BUFFER_HEADER_T

Returns:

Pointer to the newly created queue or NULL on failure.

Create a QUEUE of MMAL_BUFFER_HEADER_T

void mmal_queue_destroy

(

MMAL_QUEUE_T *

queue

)

Destroy a queue of MMAL_BUFFER_HEADER_T.

Parameters:

queue

Pointer to a queue

Destroy a queue of MMAL_BUFFER_HEADER_T

MMAL_BUFFER_HEADER_T* mmal_queue_get

(

MMAL_QUEUE_T *

queue

)

Get a MMAL_BUFFER_HEADER_T from a queue

Parameters:

queue

Pointer to a queue

Returns:

pointer to the next MMAL_BUFFER_HEADER_T or NULL if the queue is empty.

Get a MMAL_BUFFER_HEADER_T from a QUEUE.

unsigned int mmal_queue_length

(

MMAL_QUEUE_T *

queue

)

Get the number of MMAL_BUFFER_HEADER_T currently in a queue.

Parameters:

queue

Pointer to a queue

Returns:

length (in elements) of the queue.

Get the number of MMAL_BUFFER_HEADER_T currently in a QUEUE

void mmal_queue_put	(	MMAL_QUEUE_T *	queue,
		MMAL_BUFFER_HEADER_T *	buffer
	)

Put a MMAL_BUFFER_HEADER_T into a queue

Parameters:

queue	Pointer to a queue
buffer	Pointer to the MMAL_BUFFER_HEADER_T to add to the queue

Put a MMAL_BUFFER_HEADER_T into a QUEUE

void mmal_queue_put_back	(	MMAL_QUEUE_T *	queue,
		MMAL_BUFFER_HEADER_T *	buffer
	)

Put a MMAL_BUFFER_HEADER_T back at the start of a queue. This is used when a buffer header was removed from the queue but not fully processed and needs to be put back where it was originally taken.

Parameters:

queue	Pointer to a queue
buffer	Pointer to the MMAL_BUFFER_HEADER_T to add to the queue

Put a MMAL_BUFFER_HEADER_T back at the start of a QUEUE.

MMAL_BUFFER_HEADER_T* mmal_queue_wait

(

MMAL_QUEUE_T *

queue

)

Wait for a MMAL_BUFFER_HEADER_T from a queue. This is the same as a get except that this will block until a buffer header is available.

Parameters:

queue

Pointer to a queue

Returns:

pointer to the next MMAL_BUFFER_HEADER_T.

Wait for a MMAL_BUFFER_HEADER_T from a QUEUE.