cqueue.c File Reference

#include <stdlib.h>
#include "queue.h"
#include "types/err.h"

Include dependency graph for cqueue.c:

Go to the source code of this file.

Macros
#define	MIN(a, b)
#define	MAX(a, b)

Functions
void	cqueue_init (cqueue_t *queue, unsigned int max_length)
	Initializes a circular queue.
error_code_t	cqueue_add (cqueue_t *queue, int item)
	Add a value to the circular queue.
error_code_t	cqueue_get (cqueue_t *queue, int *item)
	Get the current value from the circular queue, removing it from the queue.
error_code_t	cqueue_lookup (const cqueue_t *queue, int *item, unsigned int seek)
	Get a value from the circular queue, without removing it from the queue.
int	cqueue_isempty (const cqueue_t *queue)
	Check if the given circular queue is empty.
int	cqueue_isfull (const cqueue_t *queue)
	Check if the given circular queue is full.
void	cqueue_close (cqueue_t *queue)
	Close the given circular queue.

Macro Definition Documentation

MAX

#define MAX	(		a,
			b )

Value:

(a > b ? a : b)

Definition at line 7 of file cqueue.c.

MIN

#define MIN	(		a,
			b )

Value:

(a < b ? a : b)

Definition at line 6 of file cqueue.c.

Function Documentation

cqueue_add()

error_code_t cqueue_add	(	cqueue_t *	queue,
		int	item )

Add a value to the circular queue.

Parameters

queue	The queue where to add the item.
item	The value to add.

Returns

ERR_MAX_SIZE_EXCEEDED on queue is full.

ERR_OK on added successful.

Definition at line 20 of file cqueue.c.

{
  if (cqueue_isfull(queue)) {
    return ERR_MAX_SIZE_EXCEEDED;
  }
 
  queue->_last = (queue->_last + 1) % queue->_max_length;
  queue->data[queue->_last] = item;
 
  queue->length = MIN(queue->length + 1, queue->_max_length);
 
  return ERR_OK;
}

cqueue_close()

void cqueue_close

(

cqueue_t *

queue

)

Close the given circular queue.

Parameters

The	queue to be closed.

Definition at line 80 of file cqueue.c.

{
  free(queue->data);
  queue->data = NULL;
}

cqueue_get()

error_code_t cqueue_get	(	cqueue_t *	queue,
		int *	item )

Get the current value from the circular queue, removing it from the queue.

Parameters

queue	The queue where to remove the value.
item	The pointer where the value will be saved.

Returns

ERR_EMPTY on queue is empty.

ERR_OK on value as get successful.

Definition at line 35 of file cqueue.c.

{
  if (cqueue_isempty(queue)) {
    return ERR_EMPTY;
  }
 
  *item = queue->data[queue->_current];
 
  queue->_current = (queue->_current + 1) % queue->_max_length;
  queue->length--;
 
  return ERR_OK;
}

cqueue_init()

void cqueue_init	(	cqueue_t *	queue,
		unsigned int	max_length )

Initializes a circular queue.

Parameters

queue	The queue to be initialized.
max_length	The maximum number of items to fit inside the queue.

Definition at line 10 of file cqueue.c.

{
  queue->length = 0;
  queue->_current = 0;
  queue->_last = -1;
  queue->_max_length = max_length;
  queue->data = malloc(sizeof(int) * max_length);
}

cqueue_isempty()

int cqueue_isempty

(

const cqueue_t *

queue

)

Check if the given circular queue is empty.

Parameters

queue

The queue to check if it's empty.

Returns

1 on the queue is empty.

0 on the queue has items.

Definition at line 68 of file cqueue.c.

{
  return queue->length == 0;
}

cqueue_isfull()

int cqueue_isfull

(

const cqueue_t *

queue

)

Check if the given circular queue is full.

Parameters

queue

The queue to check if it's full.

Returns

1 on the queue is full.

0 on the queue is not full.

Definition at line 74 of file cqueue.c.

{
  return queue->length >= queue->_max_length;
}

cqueue_lookup()

error_code_t cqueue_lookup	(	const cqueue_t *	queue,
		int *	item,
		unsigned int	seek )

Get a value from the circular queue, without removing it from the queue.

Parameters

queue	The queue where to get the value.
item	The pointer where the value will be saved.
seek	The index of the value to get (0 means the current, 1 the next and so one).

Returns

ERR_EMPTY on queue is empty.

ERR_INVALID_INDEX on the seek is invalid.

ERR_OK on value as get successful.

Definition at line 50 of file cqueue.c.

{
  if (cqueue_isempty(queue)) {
    return ERR_EMPTY;
  }
 
  unsigned int index = (queue->_current + seek) % queue->_max_length;
 
  if ((seek >= queue->length) || (queue->_last > queue->_current && index > queue->_last) ||
      (queue->_last < queue->_current && index < queue->_current && index > queue->_last)) {
    return ERR_INVALID_INDEX;
  }
 
  *item = queue->data[index];
  return ERR_OK;
}