SGDMA descriptor list questions

for(tse_ptr->chain_loop = 0; tse_ptr->chain_loop < ALTERA_TSE_SGDMA_RX_DESC_CHAIN_SIZE; tse_ptr->chain_loop++)

{

tse_ptr->pkt_array[tse_ptr->chain_loop] = pk_alloc(ALTERA_TSE_PKT_INIT_LEN+4);

if (!tse_ptr->pkt_array[tse_ptr->chain_loop]) /* couldn't get a free buffer for rx */

{

dprintf("[tse_sgdma_read_init] Fatal error: No free packet buffers for RX\n");

tse_ptr->netp->n_mib->ifInDiscards++;

return ENP_NOBUFFER;

}

// ensure bit-31 of tse_ptr->pkt_array[tse_ptr->chain_loop]->nb_buff is clear before passing

// to SGDMA Driver

uncached_packet_payload = (alt_u32 *)alt_remap_cached ((volatile void*) tse_ptr->pkt_array[tse_ptr->chain_loop]->nb_buff, 4);

alt_avalon_sgdma_construct_stream_to_mem_desc(

(alt_sgdma_descriptor *) &tse_ptr->desc[tse_ptr->chain_loop+ALTERA_TSE_FIRST_RX_SGDMA_DESC_OFST], // descriptor I want to work with

(alt_sgdma_descriptor *) &tse_ptr->desc[tse_ptr->chain_loop+ALTERA_TSE_SECOND_RX_SGDMA_DESC_OFST], // pointer to "next"

uncached_packet_payload, // tse_ptr->pkt_array[tse_ptr->chain_loop]->nb_buff, // starting write_address

0, // read until EOP

0); // don't write to constant address

}

I find the code in the TSE MAC IP.