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TNeoKernel
v1.02
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TNeoKernel
v1.02
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A data queue is a FIFO that stores pointer (of type void *) in each cell, called (in uITRON style) a data element.
A data queue also has an associated wait queue each for sending (wait_send queue) and for receiving (wait_receive queue). A task that sends a data element tries to put the data element into the FIFO. If there is no space left in the FIFO, the task is switched to the waiting state and placed in the data queue's wait_send queue until space appears (another task gets a data element from the data queue). A task that receives a data element tries to get a data element from the FIFO. If the FIFO is empty (there is no data in the data queue), the task is switched to the waiting state and placed in the data queue's wait_receive queue until data element arrive (another task puts some data element into the data queue). To use a data queue just for the synchronous message passing, set size of the FIFO to 0. The data element to be sent and received can be interpreted as a pointer or an integer and may have value 0 (NULL).
Definition in file tn_dqueue.h.
Go to the source code of this file.
Data Structures | |
| struct | TN_DQueue |
| Structure representing data queue object. More... | |
| struct | TN_DQueueTaskWait |
| DQueue-specific fields related to waiting task, to be included in struct TN_Task. More... | |
Functions | |
| enum TN_RCode | tn_queue_create (struct TN_DQueue *dque, void **data_fifo, int items_cnt) |
| Construct data queue. More... | |
| enum TN_RCode | tn_queue_delete (struct TN_DQueue *dque) |
| Destruct data queue. More... | |
| enum TN_RCode | tn_queue_send (struct TN_DQueue *dque, void *p_data, TN_Timeout timeout) |
Send the data element specified by the p_data to the data queue specified by the dque. More... | |
| enum TN_RCode | tn_queue_send_polling (struct TN_DQueue *dque, void *p_data) |
The same as tn_queue_send() with zero timeout. More... | |
| enum TN_RCode | tn_queue_isend_polling (struct TN_DQueue *dque, void *p_data) |
The same as tn_queue_send() with zero timeout, but for using in the ISR. More... | |
| enum TN_RCode | tn_queue_receive (struct TN_DQueue *dque, void **pp_data, TN_Timeout timeout) |
Receive the data element from the data queue specified by the dque and place it into the address specified by the pp_data. More... | |
| enum TN_RCode | tn_queue_receive_polling (struct TN_DQueue *dque, void **pp_data) |
The same as tn_queue_receive() with zero timeout. More... | |
| enum TN_RCode | tn_queue_ireceive_polling (struct TN_DQueue *dque, void **pp_data) |
The same as tn_queue_receive() with zero timeout, but for using in the ISR. More... | |
Construct data queue.
id_dque member should not contain TN_ID_DATAQUEUE, otherwise, TN_RC_WPARAM is returned.
| dque | pointer to already allocated struct TN_DQueue. |
| data_fifo | pointer to already allocated array of void * to store data queue items. Can be NULL. |
| items_cnt | capacity of queue (count of elements in the data_fifo array) Can be 0. |
TN_RC_OK if queue was successfully created;TN_CHECK_PARAM is non-zero, additional return code is available: TN_RC_WPARAM. Destruct data queue.
All tasks that wait for writing to or reading from the queue become runnable with TN_RC_DELETED code returned. TN_RCode, struct TN_Task.
| dque | pointer to data queue to be deleted |
TN_RC_OK if queue was successfully deleted;TN_RC_WCONTEXT if called from wrong context;TN_CHECK_PARAM is non-zero, additional return codes are available: TN_RC_WPARAM and TN_RC_INVALID_OBJ. | enum TN_RCode tn_queue_send | ( | struct TN_DQueue * | dque, |
| void * | p_data, | ||
| TN_Timeout | timeout | ||
| ) |
Send the data element specified by the p_data to the data queue specified by the dque.
If there are tasks in the data queue's wait_receive list already, the function releases the task from the head of the wait_receive list, makes this task runnable and transfers the parameter p_data to task's function, that caused it to wait.
If there are no tasks in the data queue's wait_receive list, parameter p_data is placed to the tail of data FIFO. If the data FIFO is full, behavior depends on the timeout value: refer to TN_Timeout.
| dque | pointer to data queue to send data to |
| p_data | value to send |
| timeout | refer to TN_Timeout |
TN_RC_OK if data was successfully sent;TN_RC_WCONTEXT if called from wrong context;timeout value, refer to TN_TimeoutTN_CHECK_PARAM is non-zero, additional return codes are available: TN_RC_WPARAM and TN_RC_INVALID_OBJ.TN_Timeout The same as tn_queue_send() with zero timeout, but for using in the ISR.
| enum TN_RCode tn_queue_receive | ( | struct TN_DQueue * | dque, |
| void ** | pp_data, | ||
| TN_Timeout | timeout | ||
| ) |
Receive the data element from the data queue specified by the dque and place it into the address specified by the pp_data.
If the FIFO already has data, function removes an entry from the end of the data queue FIFO and returns it into the pp_data function parameter.
If there are task(s) in the data queue's wait_send list, first one gets removed from the head of wait_send list, becomes runnable and puts the data entry, stored in this task, to the tail of data FIFO. If there are no entries in the data FIFO and there are no tasks in the wait_send list, behavior depends on the timeout value: refer to TN_Timeout.
| dque | pointer to data queue to receive data from |
| pp_data | pointer to location to store the value |
| timeout | refer to TN_Timeout |
TN_RC_OK if data was successfully received;TN_RC_WCONTEXT if called from wrong context;timeout value, refer to TN_TimeoutTN_CHECK_PARAM is non-zero, additional return codes are available: TN_RC_WPARAM and TN_RC_INVALID_OBJ.TN_Timeout The same as tn_queue_receive() with zero timeout, but for using in the ISR.
1.8.8