The Raw API is callback based. Applications obtain access directly into the TCP stack and vice-versa. As a result, there is no extra socket layer, and using the Raw API provides excellent performance at the price of compatibility with other TCP stacks.
Xilinx Adapter Requirements when using the RAW API
In addition to the lwIP RAW API, the Xilinx adapters provide the xemacif_input utility function for receiving packets. This function must be called at frequent intervals to move the received packets from the interrupt handlers to the lwIP stack. Depending on the type of packet received, lwIP then calls registered application callbacks.
The <Vitis_install_path>/sw/ThirdParty/sw_services/lwip213/src/lwip-2.1.3/doc/rawapi.txt file describes the lwIP Raw API.
RAW API Example
int main()
{
struct netif *netif, server_netif;
ip_addr_t ipaddr, netmask, gw;
unsigned char mac_ethernet_address[] =
{0x00, 0x0a, 0x35, 0x00, 0x01, 0x02};
lwip_init();
if (!xemac_add(netif, &ipaddr, &netmask,
&gw, mac_ethernet_address,
EMAC_BASEADDR)) {
printf(“Error adding N/W interface\n\r”);
return -1;
}
netif_set_default(netif);
platform_enable_interrupts();
netif_set_up(netif);
start_application();
while (1) {
xemacif_input(netif);
transfer_data();
}
}