91 lines
1.9 KiB
C
91 lines
1.9 KiB
C
#include "smackqueue.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/****************************************************************************
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* Build a queue so that we can do a breadth-first enumeration of the
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* sub-patterns
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****************************************************************************/
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struct QueueElement
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{
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unsigned m_data;
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struct QueueElement *m_next;
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};
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struct Queue
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{
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struct QueueElement *m_head;
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struct QueueElement *m_tail;
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};
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struct Queue *
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queue_create(void)
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{
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struct Queue *queue;
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queue = (struct Queue *)malloc(sizeof(*queue));
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if (queue == NULL) {
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fprintf(stderr, "%s: out of memory error\n", "smack");
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exit(1);
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}
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memset(queue, 0, sizeof(*queue));
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return queue;
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}
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void
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queue_destroy(struct Queue * queue)
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{
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if (queue == NULL)
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return;
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while (queue_has_more_items(queue))
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dequeue(queue);
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free(queue);
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}
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void
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enqueue(struct Queue *queue, unsigned data)
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{
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struct QueueElement *element;
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element = (struct QueueElement *)malloc(sizeof (struct QueueElement));
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if (element == NULL) {
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fprintf(stderr, "%s: out of memory error\n", "smack");
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exit(1);
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}
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if (queue->m_head == NULL) {
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/* If nothing in the queue, initialize the queue with the
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* first data */
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queue->m_head = element;
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} else {
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/* Else, add the data to the tail of the queue */
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queue->m_tail->m_next = element;
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}
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element->m_data = data;
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element->m_next = NULL;
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queue->m_tail = element;
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}
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unsigned
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dequeue(struct Queue *queue)
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{
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if (queue->m_head == NULL)
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return 0;
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else {
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struct QueueElement *element;
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unsigned result;
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element = queue->m_head;
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result = element->m_data;
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queue->m_head = element->m_next;
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free(element);
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return result;
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}
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}
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unsigned queue_has_more_items(struct Queue * queue)
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{
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return queue->m_head != NULL;
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}
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