Queue

#include <QCoreApplication>
#include <stdio.h>
#define STATUS_OK               (0)  /* Successfully completed. */
#define STATUS_ERR_INVALID     (-1)  /* Bad argument value. E.g. null pointer */
#define STATUS_ERR_NOMEM       (-2)  /* No memory to complete operation. */
#define STATUS_ERR_NODATA      (-3)  /* No data to return/process. */
#define STATUS_ERR_SINGULAR (-0x10)  /* The matrix is singular (degenerative) */
typedef struct _PrQueue PrQueue;
struct _PrQueue
{
    void * p_data;
    int n_priority;
    size_t n_max_size;
};
int prQueueCreate(size_t n_capacity, PrQueue ** pp_queue)
{
    if(n_capacity == 0)
        return STATUS_ERR_NOMEM;
    *pp_queue = (PrQueue *) malloc(sizeof(PrQueue)*n_capacity);
    for( size_t j = 0; j< n_capacity; j++)
    {
        (*pp_queue)[j].p_data = NULL;
        (*pp_queue)[j].n_priority = -1;
        (*pp_queue)[j].n_max_size = n_capacity;
    }
    if(!pp_queue)
        return STATUS_ERR_INVALID;
    return STATUS_OK;
}

int prQueuePush(PrQueue * p_queue, int n_priority, void * p_item)
{
    if(!p_item )
        return STATUS_ERR_INVALID;

    if(!((*p_queue).p_data))
    {
        (*p_queue).n_priority = n_priority;
        (*p_queue).p_data = p_item;
    }
    else
    {
        size_t n_count  = 0;
        while((*p_queue).p_data)
        {
            n_count++;
            if((*(p_queue)).n_max_size  <=  n_count )
                return STATUS_ERR_NOMEM;
            else
                p_queue++;
        }
        (*p_queue).n_priority = n_priority;
        (*p_queue).p_data = p_item;
    }
    (*(p_queue+1)).p_data = NULL;
    (*(p_queue+1)).n_priority = -1;

    return STATUS_OK;
}

int prQueuePeek(PrQueue * p_queue, int * n_priority, void ** pp_item)
{
    if(!pp_item)
        return STATUS_ERR_INVALID;
    int n_count = 0;
    int n_min_priority = (*p_queue).n_priority;
    while( (*p_queue).p_data )
    {
        n_count++;
        if ( (*p_queue).n_priority < n_min_priority )
            n_min_priority = (*p_queue).n_priority;
        p_queue++;
    }
    if(n_count <= 0 )
        return STATUS_ERR_NODATA;
    while((*(--p_queue)).n_priority != n_min_priority )
    {}
    *n_priority = n_min_priority;
    *pp_item = (*p_queue).p_data;

    return STATUS_OK;
}

int prQueuePop(PrQueue * p_queue, int *n_priority, void **pp_item)
{
    int n_status = prQueuePeek(p_queue,n_priority,pp_item);
    if( n_status != STATUS_OK )
        return n_status;
    size_t n_count=0;
    PrQueue * p_tmp = p_queue;
    while( (*p_queue).p_data )
    {
        n_count++;
        p_queue++;
    }
    p_queue = p_tmp;
    while( n_count > 1 )
    {
        (*p_queue).n_priority = (*(p_queue+1)).n_priority;
        (*p_queue).p_data = (*(p_queue+1)).p_data;
        p_queue++;
        n_count--;
    }
    if( n_count <= 1 )
    {
        printf("%d  - \n",(*p_queue).p_data);
    }
    else
    {
        (*p_queue).p_data = NULL;
        (*p_queue).n_priority = -1;
    }

    return STATUS_OK;
}

void prQueueRelease(PrQueue * p_queue)
{
    while( (*p_queue).p_data )
    {
        (*p_queue).p_data = NULL;
        (*p_queue).n_priority = -1;
        p_queue++;
    }
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    PrQueue* pr_queue;
    prQueueCreate(4,&pr_queue);
    printf("state1 %d \n",prQueuePush(pr_queue,7,(void *)NULL));
    prQueuePush(pr_queue,0,(int*)12);
    prQueuePush(pr_queue,1,(int*)13);
    prQueuePush(pr_queue,2,(int*)15);
    prQueuePush(pr_queue,3,(int*)156);
    printf("state2 %d \n",prQueuePush(pr_queue,7,(int*)152));
    for( int i = 0; i < 4; i++)
    {
        printf("%d \t",pr_queue[i].n_priority);
        printf("%d \t",int(pr_queue[i].p_data));
        printf("%d \n",pr_queue[i].n_max_size);
    }
    printf("\n");
    PrQueue *pr_queue_del;
    prQueueCreate(4,&pr_queue_del);
    prQueuePop(pr_queue,&pr_queue_del[0].n_priority,&pr_queue_del[0].p_data);
    prQueuePop(pr_queue,&pr_queue_del[1].n_priority,&pr_queue_del[1].p_data);
    prQueuePop(pr_queue,&pr_queue_del[2].n_priority,&pr_queue_del[2].p_data);
    prQueuePop(pr_queue,&pr_queue_del[3].n_priority,&pr_queue_del[3].p_data);
    for( int i = 0; i < 4; i++)
    {
        printf("%d \t",pr_queue[i].n_priority);
        printf("%d \t",int(pr_queue[i].p_data));
        printf("%d \n",pr_queue[i].n_max_size);
    }
    printf("\n");
    printf("remove - %d  \t %d \n",pr_queue_del[0].n_priority,int(pr_queue_del[0].p_data));
    printf("\n");
    prQueueRelease(pr_queue);
    prQueueRelease(pr_queue_del);
    return a.exec();
}