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IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ #ifndef SYS_QUEUE_H_INCLUDED #define SYS_QUEUE_H_INCLUDED #include #include /** @file * This file contains declarations of the primitives to work with queues and necessary types. * * @defgroup sys_queues Queue API * @ingroup sys_15_4 * @{ * @brief Module to declare the queue API. * @details The queue module implements a set of routines to deal with queues. Before * any calls to its API are issued, a queue must be initialized using sys_queue_init(). The following routines * return queue items from different parts of an initialized queue without removing it from the queue: * sys_queue_front(), sys_queue_back(), sys_queue_next(), and sys_queue_at(). * The following routines insert elements to the queue: sys_queue_push_front(), * sys_queue_push_back(), sys_queue_push_predicated(), sys_queue_push_predicated_force(), and sys_queue_insert(). * The following routines remove elements from the queue: sys_queue_pop_front(), sys_queue_remove(), * sys_queue_remove_after(). These helper routines get information about a queue: sys_queue_size() and * sys_queue_is_empty(). The module also supports an iterator macro implemented by SYS_QUEUE_FOR_EACH(). */ /**@brief Queue item descriptor. * * @details In order to store any user data struct in a queue, the user struct should contain * a field of type 'sys_queue_item_t'. This field may be at any offset. * The user data item can be cast from the queue item, * by the \ref GET_PARENT_BY_FIELD() macro from sys_utils.h. */ typedef struct sys_queue_item_s { struct sys_queue_item_s * next; } sys_queue_item_t; /**@brief Queue descriptor. */ typedef sys_queue_item_t sys_queue_t; /**@brief Prototype of a predicate function for pushing an item into the queue. * * @details As a user of the queue library, implement the predicate function and pass it * as a parameter to \ref sys_queue_push_predicated(). You can choose * whether insertion of a new item should be done before the given existing item of * the queue, or not. * * @param[in] p_before_item Pointer to the existing item before which a new item * should be inserted. * @param[in] p_new_item Pointer to the item to be inserted into the queue. * * @retval true Insertion is to be done before the given item, false otherwise. */ typedef bool (* sys_queue_push_predicate_t)( sys_queue_item_t * p_before_item, sys_queue_item_t * p_new_item); /**@brief Function for initializing the queue before any other usage of the queue. * * @details Initialize (reset) the queue to its initial state. The queue becomes empty. * * @param[in] p_queue Queue to be initialized. */ void sys_queue_init(sys_queue_t * p_queue); /**@brief Function for getting the front (head) item of the queue without removing it. * * @details Return a pointer to the item from the head of the queue but leave it in the queue. * * @param[in] p_queue Queue to get the item from. * * @retval Pointer to the head item of the queue, or NULL if the queue is empty. */ sys_queue_item_t * sys_queue_front(const sys_queue_t * p_queue); /**@brief Function for getting the back (tail) item of the queue without removing it. * * @details Return a pointer to the item from the tail of the queue but leave it in the queue. * * @param[in] p_queue Queue to get the item from. * * @retval Pointer to the tail item of the queue, or NULL if the queue is empty. */ sys_queue_item_t * sys_queue_back(const sys_queue_t * p_queue); /**@brief Function for getting the item, next to the given item of the queue. * * @details Return a pointer to the next item after the given one, or NULL if the * given item is the last item of the queue. * * @param[in] p_queue Pointer to the queue. * @param[in] p_item Pointer to the item. * * @retval Pointer to the next item after the given one, or NULL if the * given item is the last item of the queue. */ sys_queue_item_t * sys_queue_next(const sys_queue_t * p_queue, const sys_queue_item_t * p_item); /**@brief Function for pushing an item to the front (head) of the queue. * * @details This function inserts an item to the head of the queue. * * @param[in] p_queue Queue to push the item to. * @param[in] p_item Item to insert to the front of the queue. */ void sys_queue_push_front(sys_queue_t * p_queue, sys_queue_item_t * p_item); /**@brief Function for pushing an item to the back (tail) of the queue. * * @details This function inserts an item to the tail of the queue. * * @param[in] p_queue Queue to push the item to. * @param[in] p_item Item to insert to the tail of the queue. */ void sys_queue_push_back(sys_queue_t * p_queue, sys_queue_item_t * p_item); /**@brief Function for pushing an item to the queue with a predicate. * * @details Conditionally push an item to the queue using the given predicate that tries to determine * the insertion position. * * @param[in] p_queue Queue to push the item to. * @param[in] p_item Item to be pushed. * @param[in] predicate Predicate to be used to find the insertion position. * * @retval true The item was inserted into the queue, false otherwise. */ bool sys_queue_push_predicated( sys_queue_t * p_queue, sys_queue_item_t * p_item, sys_queue_push_predicate_t predicate); /**@brief Function for pushing an item to the queue with a predicate forcing insertion to the tail if the predicate * fails. * * @details Unconditionally push an item to the queue using the given predicate that tries to * determine the insertion position. * If predicate returns false, then force the insertion to the tail of the queue. * * @param[in] p_queue Queue to push item to. * @param[in] p_item Item to be pushed. * @param[in] predicate Predicate to be used to find the insertion position. */ void sys_queue_push_predicated_force( sys_queue_t * p_queue, sys_queue_item_t * p_item, sys_queue_push_predicate_t predicate); /**@brief Function for getting and removing the front (head) item from the queue. * * @details Get an item from the head of the queue and remove it from the queue. * * @param[in] p_queue Queue to get and remove the head item from. * * @retval Pointer to the head item of queue or NULL if the queue is empty. */ sys_queue_item_t * sys_queue_pop_front(sys_queue_t * p_queue); /**@brief Function for removing an item from the queue. * * @details The given item will be removed from the queue. * * @note The complexity of this function is O(n). Use function \ref sys_queue_remove_after() * whenever the previous item of the queue is known. * * @param[in] p_queue Queue to remove the item from. * @param[in] p_item Item to remove from the queue. */ void sys_queue_remove(sys_queue_t * p_queue, sys_queue_item_t * p_item); /**@brief Function for removing the item after the given item from the queue. * * @details The item next to the given one will be removed from the queue. * * @param[in] p_queue Queue to remove the item from. * @param[in] p_after_item Next to this item will be removed. */ void sys_queue_remove_after(sys_queue_t * p_queue, sys_queue_item_t * p_after_item); /**@brief Function for returning the current size of a queue, i.e. number of elements inside it. * * @details This function goes through the whole queue, so it is relatively slow. * * @param[in] p_queue Queue to work with. * * @retval Number of items currently inserted into the queue. */ uint8_t sys_queue_size(const sys_queue_t * p_queue); /**@brief Function for returning a pointer to the item inside a queue represented by an index. * * @details This function searches through the whole queue, so it is relatively slow. * * @param[in] p_queue Queue to work with. * @param[in] index Requested index. * * @retval Pointer to the requested item or NULL if the queue size is less * than \a index. */ sys_queue_item_t * sys_queue_at(const sys_queue_t * p_queue, const uint8_t index); /**@brief Function for inserting an item at the specified position represented by an index in the queue. * If this position is too big, it is inserted to the tail of the queue. * * @details This function searches through the whole queue, so it is relatively slow. * * @param[in] p_queue Queue to insert to. * @param[in] p_item Item to be inserted. * @param[in] pos Position inside the queue (0 is the front). */ void sys_queue_insert(sys_queue_t * p_queue, sys_queue_item_t * p_item, const uint8_t pos); /**@brief Function for determining if a queue is empty. * * @param[in] p_queue Queue to be checked. * * @retval True if queue is empty, false otherwise. */ bool sys_queue_is_empty(const sys_queue_t * p_queue); /**@brief Macro for iterating through all items in the queue. * * @param[in] p_queue Pointer to the queue (sys_queue_t *). * @param[in] p_iterator Variable to be used as an iterator (sys_queue_item_t *). */ #define SYS_QUEUE_FOR_EACH(p_queue, p_iterator) \ for (sys_queue_item_t * p_iterator = sys_queue_front(p_queue); \ p_iterator != NULL; \ p_iterator = sys_queue_next(p_queue, p_iterator)) /** @} */ #endif // SYS_QUEUE_H_INCLUDED