UDP for IPv4

The UDP library provides functions for creating and manipulation UDP packets.

Functionality

Create UDP packets of any length
Create and extract UDP headers
Verify checksum of UDP packets

Example use

Include the libraries:

library nw_util;
context nw_util.nw_util_context;
library nw_ipv4;
context nw_ipv4.nw_ipv4_context;

Assume the variable v_payload contains the UDP payload. The variables are defined:

variable v_header  : t_udp_header; -- UDP header record
variable v_udp_pkt : t_slv_arr(0 to 1500)(7 downto 0); -- byte array
variable v_len     : natural;

First setup the header, then calculate the total UDP packet length before creating the packet. Checksum is optional for UDP over IPv4. Here it will be set to x"0000".

v_header                  := C_DEFAULT_UDP_HEADER; -- copy default header
v_header.src_port         := x"0101"; -- change source port
v_len                     := f_udpv4_create_pkt_len(v_header, v_payload); -- calculate total packet length
v_udp_pkt(0 to v_len - 1) := f_udpv4_create_pkt(v_header, v_payload); -- create the packet (no checksum)

If checksum is desired, the IPv4 header must be supplied for the pseudo header:

v_ipv4_header := C_DEFAULT_IPV4_HEADER; -- copy default header

v_udp_pkt(0 to v_len - 1) := f_udpv4_create_pkt(v_ipv4_header, v_header, v_payload); -- create the packet

The variable v_udp_pkt is an 8-bit array. This can of course be rearranged to any word width with f_repack .

v_ipv4_pkt_32 := f_repack(v_udp_pkt, 32, C_MSB_FIRST); -- repack to 32bit words (padded with zeros if required)

See further examples in the test bench nw_ipv4_tb.vhd.

Table of Contents

UDP for IPv4

Functionality

Example use