| 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162 |
- #ifndef _QUEUE_H_
- #define _QUEUE_H_
- /*
- * Queue of void pointers, implemented as a ring buffer.
- *
- * Functions:
- * q_create - allocate a new queue, with initial size SIZE.
- * Returns NULL on error.
- * q_preallocate - extend the queue if necessary so its size is
- * at least SIZE. Returns an error code.
- * q_empty - return true if queue is empty.
- * q_addtail - add a pointer to the tail of the queue. If the queue
- * overflows, it will extend itself, but this is slow.
- * Returns an error code if the extension fails. Does not
- * fail if no extension is required.
- * q_remhead - remove a pointer from the head of the queue. If the
- * queue is empty, panics.
- * q_destroy - dispose of the queue.
- * q_peek - return pointer to front element, if empty returns null
- * q_len - returns the number of elements in the queue
- * (q_getsize is the maximum number of elements that
- * can be in the queue)
- */
- struct queue; /* Opaque. */
- struct queue *q_create(int size);
- int q_preallocate(struct queue *, int size);
- int q_empty(struct queue *);
- int q_addtail(struct queue *, void *ptr);
- void *q_remhead(struct queue *);
- void q_destroy(struct queue *);
- void *q_peek(struct queue *q);
- int q_len(struct queue *theq);
- /*
- * These are really intended only for debugging. Using them encodes
- * knowledge of how the queue works, which is usually undesirable.
- *
- * q_getstart - return the index of the front of the queue
- * q_getend - return the index of the back of the queue
- * q_getsize - return the current size of the queue
- * q_getguy - return queue member by index
- *
- * To iterate over the queue, do something like
- * struct queue *q;
- * int i;
- *
- * for (i=q_getstart(q); i!=q_getend(q); i=(i+1)%q_getsize(q)) {
- * void *ptr = q_getguy(q, i);
- * :
- * }
- *
- * If you do this, synchronization is your problem.
- */
- int q_getstart(struct queue *);
- int q_getend(struct queue *);
- int q_getsize(struct queue *);
- void *q_getguy(struct queue *, int index);
- #endif /* _QUEUE_H_ */
|
