// Send an ethernet packet over GMII
|
// Send an ethernet packet over GMII
|
|
|
module gmii_driver
|
module gmii_driver
|
(output reg [7:0] rxd,
|
(output reg [7:0] rxd,
|
output reg rx_dv,
|
output reg rx_dv,
|
output reg rx_clk);
|
output reg rx_clk);
|
|
|
integer startup_skew;
|
integer startup_skew;
|
|
|
reg [7:0] rxbuf [0:2048];
|
reg [7:0] rxbuf [0:2048];
|
reg [31:0] crc32_result;
|
reg [31:0] crc32_result;
|
|
|
// begin start clock with random skew amount
|
// begin start clock with random skew amount
|
initial
|
initial
|
begin
|
begin
|
startup_skew = {$random} % 200;
|
startup_skew = {$random} % 200;
|
rx_clk = 0;
|
rx_clk = 0;
|
rx_dv = 0;
|
rx_dv = 0;
|
rxd = 0;
|
rxd = 0;
|
repeat (startup_skew) #0.1;
|
repeat (startup_skew) #0.1;
|
forever rx_clk = #4 ~rx_clk;
|
forever rx_clk = #4 ~rx_clk;
|
end
|
end
|
|
|
// Copied from: http://www.mindspring.com/~tcoonan/gencrc.v
|
// Copied from: http://www.mindspring.com/~tcoonan/gencrc.v
|
//
|
//
|
// Generate a (DOCSIS) CRC32.
|
// Generate a (DOCSIS) CRC32.
|
//
|
//
|
// Uses the GLOBAL variables:
|
// Uses the GLOBAL variables:
|
//
|
//
|
// Globals referenced:
|
// Globals referenced:
|
// parameter CRC32_POLY = 32'h04C11DB7;
|
// parameter CRC32_POLY = 32'h04C11DB7;
|
// reg [ 7:0] crc32_packet[0:255];
|
// reg [ 7:0] crc32_packet[0:255];
|
// integer crc32_length;
|
// integer crc32_length;
|
//
|
//
|
// Globals modified:
|
// Globals modified:
|
// reg [31:0] crc32_result;
|
// reg [31:0] crc32_result;
|
//
|
//
|
localparam CRC32_POLY = 32'h04C11DB7;
|
localparam CRC32_POLY = 32'h04C11DB7;
|
task gencrc32;
|
task gencrc32;
|
input [31:09] crc32_length;
|
input [31:09] crc32_length;
|
integer cbyte, cbit;
|
integer cbyte, cbit;
|
reg msb;
|
reg msb;
|
reg [7:0] current_cbyte;
|
reg [7:0] current_cbyte;
|
reg [31:0] temp;
|
reg [31:0] temp;
|
begin
|
begin
|
crc32_result = 32'hffffffff;
|
crc32_result = 32'hffffffff;
|
for (cbyte = 0; cbyte < crc32_length; cbyte = cbyte + 1) begin
|
for (cbyte = 0; cbyte < crc32_length; cbyte = cbyte + 1) begin
|
current_cbyte = rxbuf[cbyte];
|
current_cbyte = rxbuf[cbyte];
|
for (cbit = 0; cbit < 8; cbit = cbit + 1) begin
|
for (cbit = 0; cbit < 8; cbit = cbit + 1) begin
|
msb = crc32_result[31];
|
msb = crc32_result[31];
|
crc32_result = crc32_result << 1;
|
crc32_result = crc32_result << 1;
|
if (msb != current_cbyte[cbit]) begin
|
if (msb != current_cbyte[cbit]) begin
|
crc32_result = crc32_result ^ CRC32_POLY;
|
crc32_result = crc32_result ^ CRC32_POLY;
|
crc32_result[0] = 1;
|
crc32_result[0] = 1;
|
end
|
end
|
end
|
end
|
end
|
end
|
|
|
// Last step is to "mirror" every bit, swap the 4 bytes, and then complement each bit.
|
// Last step is to "mirror" every bit, swap the 4 bytes, and then complement each bit.
|
//
|
//
|
// Mirror:
|
// Mirror:
|
for (cbit = 0; cbit < 32; cbit = cbit + 1)
|
for (cbit = 0; cbit < 32; cbit = cbit + 1)
|
temp[31-cbit] = crc32_result[cbit];
|
temp[31-cbit] = crc32_result[cbit];
|
|
|
// Swap and Complement:
|
// Swap and Complement:
|
crc32_result = ~{temp[7:0], temp[15:8], temp[23:16], temp[31:24]};
|
crc32_result = ~{temp[7:0], temp[15:8], temp[23:16], temp[31:24]};
|
end
|
end
|
endtask
|
endtask
|
|
|
|
task print_packet;
|
|
input [31:0] length;
|
|
integer i;
|
|
begin
|
|
for (i=0; i<length; i=i+1)
|
|
begin
|
|
if (i % 16 == 0) $write ("%x: ", i[15:0]);
|
|
$write ("%x ", rxbuf[i]);
|
|
if (i % 16 == 7) $write ("| ");
|
|
if (i % 16 == 15) $write ("\n");
|
|
end
|
|
if (i % 16 != 0) $write ("\n");
|
|
end
|
|
endtask
|
|
|
task send_packet;
|
task send_packet;
|
input [47:0] da, sa;
|
input [47:0] da, sa;
|
input [15:0] length;
|
input [15:0] length;
|
integer p;
|
integer p;
|
begin
|
begin
|
{ rxbuf[0],rxbuf[1],rxbuf[2],rxbuf[3],rxbuf[4],rxbuf[5] } = da;
|
{ rxbuf[0],rxbuf[1],rxbuf[2],rxbuf[3],rxbuf[4],rxbuf[5] } = da;
|
{ rxbuf[6],rxbuf[7],rxbuf[8],rxbuf[9],rxbuf[10],rxbuf[11] } = sa;
|
{ rxbuf[6],rxbuf[7],rxbuf[8],rxbuf[9],rxbuf[10],rxbuf[11] } = sa;
|
for (p=12; p<length; p=p+1)
|
for (p=12; p<length; p=p+1)
|
rxbuf[p] = $random;
|
rxbuf[p] = $random;
|
|
|
gencrc32 (length);
|
gencrc32 (length);
|
{ rxbuf[length-4], rxbuf[length-3],
|
{ rxbuf[length-4], rxbuf[length-3],
|
rxbuf[length-2], rxbuf[length-1] } = crc32_result;
|
rxbuf[length-2], rxbuf[length-1] } = crc32_result;
|
|
|
$display ("%m : Sending packet DA=%x SA=%x of length %0d", da, sa, length);
|
$display ("%m : Sending packet DA=%x SA=%x of length %0d", da, sa, length);
|
|
print_packet (length);
|
|
|
repeat (7)
|
repeat (7)
|
begin
|
begin
|
@(posedge rx_clk);
|
@(posedge rx_clk);
|
rx_dv <= #1 1;
|
rx_dv <= #1 1;
|
rxd <= #1 `GMII_PRE;
|
rxd <= #1 `GMII_PRE;
|
end
|
end
|
|
|
@(posedge rx_clk);
|
@(posedge rx_clk);
|
rxd <= #1 `GMII_SFD;
|
rxd <= #1 `GMII_SFD;
|
|
|
p = 0;
|
p = 0;
|
while (p < length)
|
while (p < length)
|
begin
|
begin
|
@(posedge rx_clk);
|
@(posedge rx_clk);
|
rxd <= #1 rxbuf[p];
|
rxd <= #1 rxbuf[p];
|
p = p + 1;
|
p = p + 1;
|
end
|
end
|
|
|
// complete 12B inter frame gap
|
// complete 12B inter frame gap
|
repeat (12)
|
repeat (12)
|
begin
|
begin
|
@(posedge rx_clk);
|
@(posedge rx_clk);
|
rx_dv <= #1 0;
|
rx_dv <= #1 0;
|
rxd <= #1 0;
|
rxd <= #1 0;
|
end
|
end
|
end
|
end
|
endtask // send_packet
|
endtask // send_packet
|
|
|
|
|
endmodule // gmii_driver
|
endmodule // gmii_driver
|
|
|
