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/*
* ipv4_tx.v
*
* Copyright 2025 Private Island Networks Inc.
* Copyright 2018, 2019, 2020 Mind Chasers Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* function: Layer 3 (and 4) Support for Controller Transmit
*
*
*/
module ipv4_tx_c(
input rstn,
input phy_resetn,
input clk,
// Control Interface
input cont_clk, // controller clock
input cont_sel,
input cont_we,
input [7:0] cont_addr,
input [15:0] cont_d_i,
output reg [15:0] cont_d_o,
// Line State
input mode_100Mbit,
input phy_up,
// Switch I/F
input [2:0] tx_mode,
input [2:0] tx_src_sel,
input [10:0] byte_cnt_i,
// MAC Interface
input fifo_re_i,
output reg fifo_empty_o,
output reg [8:0] fifo_d_o,
// Debug
output [7:0] gpio
);
`define INCLUDED
`include "ethernet_params.v"
`include "rgmii_params.v"
`undef INCLUDED
localparam TX_CNT_OFFSET = 11'h15; // offset for start of IP Header in Ethernet frame
localparam TX_CNT_CKSUM_START = TX_CNT_OFFSET + 10;
wire ipv4_hdr_active;
reg [10:0] tx_cnt;
reg [17:0] ipv4_cksum;
reg [15:0] ipv4_pkt_length;
reg [15:0] udp_pkt_length;
integer i;
assign ipv4_hdr_active = (tx_mode == TX_MODE_XMT_CUSTOM && tx_src_sel == TX_SRC_SEL_UC);
always @(posedge clk, negedge rstn)
if ( !rstn )
tx_cnt <= 11'd0;
else if (ipv4_hdr_active)
tx_cnt <= tx_cnt + 1'b1;
else
tx_cnt <= 11'd0;
always @(posedge clk, negedge rstn)
if ( !rstn ) begin
ipv4_pkt_length <= 16'd0;
udp_pkt_length <= 16'd0;
end
else if (ipv4_hdr_active && tx_cnt == 11'd0) begin
ipv4_pkt_length <= byte_cnt_i + SZ_IPV4_HEADER + SZ_UDP_HEADER;
udp_pkt_length <= byte_cnt_i + SZ_UDP_HEADER;
end
always @(posedge clk, negedge rstn)
if ( !rstn )
ipv4_cksum <= 18'd0;
else if (!ipv4_hdr_active)
ipv4_cksum <= 18'd0;
else if (tx_cnt < 11'd20 && tx_cnt[0])
ipv4_cksum <= ipv4_cksum + (ipv4_hdr(tx_cnt-1)<<8) + ipv4_hdr(tx_cnt);
// else if (tx_cnt == 11'd20)
// ipv4_cksum <= ipv4_cksum + ipv4_pkt_length;
else if (tx_cnt == 11'd21)
ipv4_cksum <= {2'b00,ipv4_cksum[15:0]} + {16'h0000,ipv4_cksum[17:16]};
else if (tx_cnt == 11'd22)
ipv4_cksum <= {2'b00, ~ipv4_cksum[15:0]};
// fifo_empty_o
always @(posedge clk, negedge rstn)
if ( !rstn )
fifo_empty_o <= 1'b1;
else if (tx_cnt >= TX_CNT_OFFSET && tx_cnt < (TX_CNT_OFFSET + SZ_IPV4_HEADER + SZ_UDP_HEADER))
fifo_empty_o <= 1'b0;
else
fifo_empty_o <= 1'b1;
// fifo_d_o
always @(posedge clk, negedge rstn)
if ( !rstn )
fifo_d_o <= 9'h000;
else if (tx_cnt == TX_CNT_CKSUM_START)
fifo_d_o <= ipv4_cksum[15:8];
else if (tx_cnt == TX_CNT_CKSUM_START+1)
fifo_d_o <= ipv4_cksum[7:0];
else if (tx_cnt >= TX_CNT_OFFSET && tx_cnt < TX_CNT_OFFSET + SZ_IPV4_HEADER)
fifo_d_o <= ipv4_hdr(tx_cnt-TX_CNT_OFFSET);
else if (tx_cnt >= TX_CNT_OFFSET && tx_cnt < TX_CNT_OFFSET + SZ_IPV4_HEADER + SZ_UDP_HEADER)
fifo_d_o <= udp_hdr(tx_cnt-(TX_CNT_OFFSET + SZ_IPV4_HEADER));
else
fifo_d_o <= 9'h000;
// generate the IPv4 header
// Assuming the header is only 20 bytes, this is both efficient and flexible
function automatic [7:0] ipv4_hdr;
input [10:0] ad;
case(ad)
0: ipv4_hdr = 8'h45; // Version
1: ipv4_hdr = 8'h00; // IHL
2: ipv4_hdr = ipv4_pkt_length[15:8]; // Total Length
3: ipv4_hdr = ipv4_pkt_length[7:0];
4: ipv4_hdr = 8'h54;
5: ipv4_hdr = 8'hDB;
6: ipv4_hdr = 8'h40;
7: ipv4_hdr = 8'h00;
8: ipv4_hdr = 8'h40; // TTL
9: ipv4_hdr = 8'h11; // L4 Protocol (UDP=0x11)
10: ipv4_hdr = 8'h00; // Checksum
11: ipv4_hdr = 8'h00;
12: ipv4_hdr = 8'd192; // IP Source Address
13: ipv4_hdr = 8'd168;
14: ipv4_hdr = 8'd5;
15: ipv4_hdr = 8'd100;
16: ipv4_hdr = 8'd192; // IP Destination Address
17: ipv4_hdr = 8'd168;
18: ipv4_hdr = 8'd5;
19: ipv4_hdr = 8'd40;
default: ipv4_hdr = 8'h00;
endcase
endfunction
// generate the UDP header
function automatic [7:0] udp_hdr;
input [10:0] ad;
case(ad)
0: udp_hdr = 8'h80; // SRC Port
1: udp_hdr = 8'h00; //
2: udp_hdr = 8'h80; // DST Port
3: udp_hdr = 8'h00;
4: udp_hdr = udp_pkt_length[15:8]; // Length
5: udp_hdr = udp_pkt_length[7:0];
6: udp_hdr = 8'h00; //Checksum
7: udp_hdr = 8'h00;
default: udp_hdr = 8'h00;
endcase
endfunction
assign gpio[0] = |ipv4_cksum[7:0];
assign gpio[1] = |ipv4_cksum[15:8];
endmodule
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