#define MAX_QUEUE_SIZE  1000

typedef struct
{
  void    *contents[MAX_QUEUE_SIZE];
  unsigned front, rear;
} queue;

queue   *queue_new(void);
void     queue_free(queue *);
int      queue_send(queue *, void *);
void    *queue_receive(queue *);
void    *queue_front(queue *);
unsigned queue_size(queue *);
int      queue_is_empty(queue *);