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qQueue.c File Reference

Circular-Queue Data Structure API. More…

Functions
size_t	qQueueSize (int max, size_t objsize)
	Get how much memory is needed for N objects.
int	qQueueInit (Q_QUEUE *queue, void *datamem, size_t datamemsize, size_t objsize)
	Initialize queue.
bool	qQueueClear (Q_QUEUE *queue)
	Reset queue.
bool	qQueuePush (Q_QUEUE *queue, const void *object)
	Push object into queue.
bool	qQueuePopFirst (Q_QUEUE *queue, void *object)
	Pop first pushed object from queue.
bool	qQueuePopLast (Q_QUEUE *queue, void *object)
	Pop last pushed object from queue.
bool	qQueueStatus (Q_QUEUE *queue, int *used, int *max)
	Get queue internal status.

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Detailed Description

Circular-Queue Data Structure API.

This implementation is designed to use statically allocated(fixed-size) memory for flexibilities. So you can use this queue with in shared-memory architecture to communicate with other processors.

   ----[Sample codes]----
   struct myobj {
     int integer;
     char string[255+1];
   };
   int main(void) {
     // allocate objects data memory
     size_t memsize = qQueueSize(10, sizeof(struct myobj));
     void *datamem = malloc(memsize);
     // for static data memory use can use this way
     // char datamem[NNN];
     // initialize queue
     Q_QUEUE queue;
     if(qQueueInit(&queue, datamem, memsize, sizeof(struct myobj)) == 0) {
       printf("Can't initialize queue.n");
       return -1;
     }
     // push object
     int i;
     for(i = 1; ; i++) {
       // set sample object
       struct myobj obj;
       obj.integer = i;
       sprintf(obj.string, "hello world %d", i);
       // push object
       if(qQueuePush(&queue, &obj) == false) break;
       // print debug info
       printf("Push     : %d, %sn", obj.integer, obj.string);
     }
     // pop object from head & tail
     while(true) {
       struct myobj pop;
       if(qQueuePopFirst(&queue, &pop) == false) break;
       printf("PopFirst : %d, %sn", pop.integer, pop.string);
       if(qQueuePopLast(&queue, &pop) == false) break;
       printf("PopLast  : %d, %sn", pop.integer, pop.string);
     }
     return 0;
   }
   ----[Results]----
   Push     : 1, hello world 1
   Push     : 2, hello world 2
   Push     : 3, hello world 3
   Push     : 4, hello world 4
   Push     : 5, hello world 5
   Push     : 6, hello world 6
   Push     : 7, hello world 7
   Push     : 8, hello world 8
   Push     : 9, hello world 9
   Push     : 10, hello world 10
   PopFirst : 1, hello world 1
   PopLast  : 10, hello world 10
   PopFirst : 2, hello world 2
   PopLast  : 9, hello world 9
   PopFirst : 3, hello world 3
   PopLast  : 8, hello world 8
   PopFirst : 4, hello world 4
   PopLast  : 7, hello world 7
   PopFirst : 5, hello world 5
   PopLast  : 6, hello world 6

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Function Documentation

size_t qQueueSize	(	int	max,
		size_t	objsize
	)

Get how much memory is needed for N objects.

Parameters:

	max	a number of maximum internal slots
	objsize	size of queuing object

Returns:

memory size needed

Note:

This is useful when you decide how much memory(shared-memory) required for N object entries.

int qQueueInit	(	Q_QUEUE *	queue,
		void *	datamem,
		size_t	datamemsize,
		size_t	objsize
	)

Initialize queue.

Parameters:

	queue	a pointer of Q_QUEUE
	datamem	a pointer of data memory
	datamemsize	size of datamem
	objsize	size of queuing object

Returns:

maximum number of queuing objects

     // case of dynamic data memory
     size_t memsize = qQueueSize(10, sizeof(struct myobj));
     void *datamem = malloc(memsize);
     Q_QUEUE queue;
     if(qQueueInit(&queue, datamem, memsize, sizeof(int)) == 0) {
       printf("Can't initialize queue.n");
       return -1;
     }
     // case of static data memory
     char datamem[1024];
     Q_QUEUE queue;
     if(qQueueInit(&queue, datamem, sizeof(datamem), sizeof(int)) == 0) {
       printf("Can't initialize queue.n");
       return -1;
     }

bool qQueueClear

(

Q_QUEUE *

queue

)

Reset queue.

Parameters:

queue

a pointer of Q_QUEUE

Returns:

true if successful, otherwise returns false

Note:

You do not need to call this, after qQueueInit(). This is useful when you reset all of data in the queue.

bool qQueuePush	(	Q_QUEUE *	queue,
		const void *	object
	)

Push object into queue.

Parameters:

	queue	a pointer of Q_QUEUE
	object	object pointer which points object data to push

Returns:

true if successful, otherwise(queue full or not initialized) returns false

bool qQueuePopFirst	(	Q_QUEUE *	queue,
		void *	object
	)

Pop first pushed object from queue.

Parameters:

	queue	a pointer of Q_QUEUE
	object	popped objected will be stored at this object pointer

Returns:

true if successful, otherwise(queue empty or not initialized) returns false

Note:

Can be used for FIFO implementation

bool qQueuePopLast	(	Q_QUEUE *	queue,
		void *	object
	)

Pop last pushed object from queue.

Parameters:

	queue	a pointer of Q_QUEUE
	object	popped objected will be stored at this object pointer

Returns:

true if successful, otherwise(queue empty or not initialized) returns false

Note:

Can be used for STACK implementation

bool qQueueStatus	(	Q_QUEUE *	queue,
		int *	used,
		int *	max
	)

Get queue internal status.

Parameters:

	queue	a pointer of Q_QUEUE
	used	if not NULL, a number of pushed objects will be stored
	max	if not NULL, the maximum number of pushable objects(queue size) will be stored

Returns:

true if successful, otherwise returns false

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