void *designware_emac_v3_first_free(CTL_NET_INTERFACE_t *self);
designware_emac_v3_first_free returns a pointer to the first byte free for use by the application after the allocation of transmit and receive descriptors. The client can use this to add all remaining memory to the network heap, for example.
You can call this after initializing the network interface using designware_emac_v3_init.