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| /* q.h - lock-free, non-blocking message queue. See https://github.com/fordsfords/q/tree/gh-pages */
/*
# This code and its documentation is Copyright 2014, 2015 Steven Ford, http://geeky-boy.com
# and licensed "public domain" style under Creative Commons "CC0": http://creativecommons.org/publicdomain/zero/1.0/
# To the extent possible under law, the contributors to this project have
# waived all copyright and related or neighboring rights to this work.
# In other words, you can use this code for any purpose without any
# restrictions. This work is published from: United States. The project home
# is https://github.com/fordsfords/q/tree/gh-pages
*/
#ifndef Q_H
#define Q_H
#ifdef __cplusplus
extern "C" {
#endif
typedef unsigned int qerr_t; /* see QERR_* definitions above */
struct q_s; /* forward (opaque) definition */
typedef struct q_s q_t; /* object type of queue instance */
/* Most q APIs return "qerr_t". These definitions must
* be kept in sync with the "qerrs" string array in "q.c". */
#define QERR_OK 0 /* Success */
#define QERR_BUG1 1 /* Internal software bug - should never happen */
#define QERR_BUG2 2 /* Internal software bug - should never happen */
#define QERR_BADSIZE 3 /* q_size parameter invalid */
#define QERR_MALLOCERR 4 /* No memory available */
#define QERR_FULL 5 /* No room in queue */
#define QERR_EMPTY 6 /* No messages in queue */
#define LAST_QERR 6 /* Set to value of last "QERR_*" definition */
qerr_t q_create(q_t **rtn_q, unsigned int q_size);
/* Create an instance of a queue.
* rtn_q : Pointer to caller's queue instance handle.
* q_size : Number of queue elements to allocate. Must be > 1 and a power
* of 2. Due to the nature of the algorithm used, a maximum of
* q_size - 1 elements can actually be stored in the queue.
* Returns QERR_OK on success, or other QERR_* value on error. */
qerr_t q_delete(q_t *q);
/* Delete an instance of a queue.
* q : Queue instance handle.
* Returns QERR_OK on success, or other QERR_* value on error. */
qerr_t q_enq( q_t *q, void *m);
/* Add a message to the queue.
* q : Queue instance handle.
* m : Message to enqueue.
* Returns QERR_OK on success, QERR_FULL if queue full, or other QERR_* value on error. */
qerr_t q_deq(q_t *q, void **rtn_m);
/* Remove a message from the queue.
* q : Queue instance handle.
* rtn_m : Pointer to caller's message handle.
* Returns QERR_OK on success, QERR_EMPTY if queue empty, or other QERR_* value on error. */
int q_is_empty(q_t *q);
/* Returns 1 if queue is empty (contains no messages), 0 otherwise.
* q : Queue instance handle. */
int q_is_full(q_t *q);
/* Returns 1 if queue is full (contains q_size-1 message), 0 otherwise.
* q : Queue instance handle. */
char *q_qerr_str(qerr_t qerr);
/* Returns a string representation of a queue API return error code.
* qerr : value returned by most q APIs indicating success or faiure.
* (See q.h for list of QERR_* definitions.) */
#ifdef __cplusplus
}
#endif
#endif /* Q_H */
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