/**
* Pop a pbuf packet from a pbuf packet queue
*
* @param q is the packet queue from which to pop the pbuf.
*
* @return pointer to pbuf packet if available, NULL otherswise.
*/
static struct pbuf* dequeue_packet(struct pbufq *q)
{
struct pbuf *pBuf;
SYS_ARCH_DECL_PROTECT(lev);
/**
* This entire function must run within a "critical section" to preserve
* the integrity of the transmit pbuf queue.
*
*/
SYS_ARCH_PROTECT(lev);
if (PBUF_QUEUE_EMPTY(q))
{
/* Return a NULL pointer if the queue is empty. */
pBuf = (struct pbuf *) NULL;
}
else
{
/**
* The queue is not empty so return the next frame from it
* and adjust the read pointer accordingly.
*
*/
pBuf = q->pbuf[q->qread];
q->qread = ((q->qread + 1) % STELLARIS_NUM_PBUF_QUEUE);
}
/* Return to prior interrupt state and return the pbuf pointer. */
SYS_ARCH_UNPROTECT(lev);
return (pBuf);
}
/**
* This function with either place the packet into the Stellaris transmit fifo,
* or will place the packet in the interface PBUF Queue for subsequent
* transmission when the transmitter becomes idle.
*
* @param netif the lwip network interface structure for this ethernetif
* @param p the MAC packet to send (e.g. IP packet including MAC addresses and type)
* @return ERR_OK if the packet could be sent
* an err_t value if the packet couldn't be sent
*
*/
static err_t low_level_output(struct netif *netif, struct pbuf *p)
{
LWIP_DRIVER_DATA* drv_data = (LWIP_DRIVER_DATA*)netif;
MAC_Type* mac = (MAC_Type*)netif->state;
SYS_ARCH_DECL_PROTECT(lev);
/**
* This entire function must run within a "critical section" to preserve
* the integrity of the transmit pbuf queue.
*
*/
SYS_ARCH_PROTECT(lev);
/**
* Bump the reference count on the pbuf to prevent it from being
* freed till we are done with it.
*
*/
pbuf_ref(p);
/**
* If the transmitter is idle, and there is nothing on the queue,
* send the pbuf now.
*
*/
if (PBUF_QUEUE_EMPTY(&drv_data->txq) && ((mac->MACTR & MAC_TR_NEWTX) == 0))
{
low_level_transmit(netif, p);
}
/* Otherwise place the pbuf on the transmit queue. */
else
{
/* Add to transmit packet queue */
if (!enqueue_packet(p, &drv_data->txq))
{
/* if no room on the queue, free the pbuf reference and return error. */
pbuf_free(p);
SYS_ARCH_UNPROTECT(lev);
return (ERR_MEM);
}
}
/* Return to prior interrupt state and return. */
SYS_ARCH_UNPROTECT(lev);
return (ERR_OK);
}
/**
* This function with either place the packet into the Stellaris transmit fifo,
* or will place the packet in the interface PBUF Queue for subsequent
* transmission when the transmitter becomes idle.
*
* @param netif the lwip network interface structure for this ethernetif
* @param p the MAC packet to send (e.g. IP packet including MAC addresses and type)
* @return ERR_OK if the packet could be sent
* an err_t value if the packet couldn't be sent
*
*/
static err_t
stellarisif_output(struct netif *netif, struct pbuf *p)
{
struct stellarisif *stellarisif = netif->state;
SYS_ARCH_DECL_PROTECT(lev);
/**
* This entire function must run within a "critical section" to preserve
* the integrity of the transmit pbuf queue.
*
*/
SYS_ARCH_PROTECT(lev);
/**
* Bump the reference count on the pbuf to prevent it from being
* freed till we are done with it.
*
*/
pbuf_ref(p);
/**
* If the transmitter is idle, and there is nothing on the queue,
* send the pbuf now.
*
*/
if(PBUF_QUEUE_EMPTY(&stellarisif->txq) &&
((HWREG(ETH_BASE + MAC_O_TR) & MAC_TR_NEWTX) == 0)) {
stellarisif_transmit(netif, p);
}
/* Otherwise place the pbuf on the transmit queue. */
else {
/* Add to transmit packet queue */
if(!enqueue_packet(p, &(stellarisif->txq))) {
/* if no room on the queue, free the pbuf reference and return error. */
pbuf_free(p);
SYS_ARCH_UNPROTECT(lev);
return (ERR_MEM);
}
}
/* Return to prior interrupt state and return. */
SYS_ARCH_UNPROTECT(lev);
return ERR_OK;
}
