queue.c

[詳解]

/** @file
    @brief      キュー操作

    @date       2011.03.17
    @author     Takashi SHUDO
*/

#include "queue.h"

void init_queue(struct st_queue *queue)
{
        queue->next = queue;
        queue->prev = queue;
}

/* NOT API
    @brief      末尾にキューを追加する
*/
void add_queue(struct st_queue *queue, struct st_queue *entry)
{
        entry->prev = queue->prev;
        entry->next = queue;
        queue->prev->next = entry;
        queue->prev = entry;
}

/* NOT API
    @brief      先頭にキューを挿入する
*/
void insert_queue(struct st_queue *queue, struct st_queue *entry)
{
        entry->prev = queue;
        entry->next = queue->next;
        queue->next->prev = entry;
        queue->next = entry;
}

/* NOT API
    @brief      キューを削除する
*/
void del_queue(struct st_queue *entry)
{
        entry->prev->next = entry->next;
        entry->next->prev = entry->prev;

        init_queue(entry);
}

/* NOT API
    @brief      先頭キューを削除し、戻り値として返す
*/
struct st_queue *del_next_queue(struct st_queue *queue)
{
        struct st_queue *entry = 0;

        if(queue->next == queue) {
                return entry;
        }
        entry = queue->next;

        queue->next = entry->next;
        entry->next->prev = queue;

        return entry;
}

/* NOT API
    @brief      先頭キューを末尾に移動する
*/
void rotate_queue(struct st_queue *queue)
{
        if(queue->next != queue) {
                add_queue(queue, del_next_queue(queue));
        }
}

/* NOT API
   @brief       キューが空なら0を返す
*/
int check_queue(struct st_queue *queue)
{
        if(queue->next == queue) {
                return 0;
        }

        return 1;
}