/*****************************************************************************/
/**
 * @brief       Function initializes the circular queue structure with the
 *              given buffer size of burrer and size of structure
 *
 * @note
 *
 * @param       *q -  structure pointer
 * @param       *buf - buffer pointer
 * @param       size - buffer size
 * @param       structsize - size of structure
 *
 * @return      None.
 *****************************************************************************/
void cirqueue_init(cirqueue_t * q, const void * buf, int size, int structsize)
{
    q->head = 0;
    q->tail = 0;
    q->size = size;
    q->mask = size - 1;
    q->buf = (char*) buf;
    q->structsize = structsize;
}
/*****************************************************************************/
/**
 * @brief       Reset queue of state
 *
 * @note
 *
 * @param       *q -  structure pointer
 *
 * @return      None
 *****************************************************************************/
void cirqueue_reset(cirqueue_t * q)
{
    q->tail = q->head = 0;
}
/*****************************************************************************/
/**
 * @brief       Check queue of state
 *
 * @note
 *
 * @param       *q -  structure pointer
 *
 * @return      0 - is empty / !0 - not
 *****************************************************************************/
int cirqueue_empty(cirqueue_t * q)
{
    return (q->tail == q->head) ? 0 : 1;
}
/*****************************************************************************/
/**
 * @brief       Check queue of overflow
 *
 * @note
 *
 * @param       *q -  structure pointer
 *
 * @return      0 - not / !0 - is overflow
 *****************************************************************************/
int cirqueue_overflow(cirqueue_t * q)
{
    return ((q->head - q->tail) >= q->size) ? 1 : 0;
}
/*****************************************************************************/
/**
 * @brief       Function push bytes of structure
 *
 * @note
 *
 * @param       *q -  structure pointer
 * @param       *buf - buffer pointer of structure
 *
 * @return      The number of bytes written is returned.
 *              If the head runs in to the tail, not all bytes are written
 *****************************************************************************/
int cirqueue_push(cirqueue_t * q, const void * buf)
{
    int i;
    const char * p;
    p = buf;

    for (i = 0; i < q->structsize; i++)
    {
        q->buf[q->head & q->mask] = *p++;
        q->head++;  //increment the head
    }
    return q->structsize;
}
/*****************************************************************************/
/**
 * @brief       Function reads bytes of structure
 *
 * @note
 *
 * @param       *q -  structure pointer
 * @param       *buf - buffer pointer
 *
 * @return      The number of bytes read is returned.
 *****************************************************************************/
int cirqueue_pop(cirqueue_t * q, void * buf)
{
    int i = 0;
    char * p;
    p = buf;
    if (q->tail != q->head)
    { //see if any data is available
        for (i = 0; i < q->structsize; i++)
        {
            *p++ = q->buf[q->tail & q->mask]; //grab a byte from the circular buffer
            q->tail++;  //increment the tail
            if (q->tail == q->head)
            {  //check for wrap-around
                return i; //number of bytes read
            }
        }
    }

    return i;
}