module test_fifo;

reg clk;
reg rstp;
packet_t packet_in;
reg readp;
reg writep;
packet_t packet_out;
wire emptyp;
wire fullp;


parameter depth = 2;

fifo #(depth+1) U1 (
.clk (clk),
.rstp (rstp),
.din (packet_in),
.readp (readp),
.writep (writep),
.dout (packet_out),
.emptyp (emptyp),
.fullp (fullp)
);


task read_word;
@(negedge clk);
readp = 1;
@(posedge clk) #5;
$display ("Read %h from FIFO", packet_out.src);
readp = 0;
endtask


task write_word(ubyte src, dst, ubyte [3:0] data);
@(negedge clk);
packet_in = {src,dst,data};
writep = 1;
@(posedge clk);
$display ("Write %h to FIFO", src);
#5;
packet_in = {default:'z};
writep = 0;
endtask

initial begin
//$fsdbDumpfile("run2.fsdb");
//$fsdbDumpvars("+all");
clk = 0;
forever begin
#10 clk = 1;
#10 clk = 0;
end
end

initial begin

test1;
test2;
@(posedge clk);
$finish;
end
 

// Test1
 

task test1;
begin
packet_in = {default:'z};
writep = 0;
readp = 0;

// Reset
rstp = 1;
#50;
rstp = 0;
#50;

// ** Write 3 values.
write_word (0,1,16'h1111);
write_word (1,2,16'h2222);
write_word (3,4,16'h3333);

// ** Read 2 values
read_word;
read_word;

// ** Write one more
write_word (5,6,16'h4444);

// ** Read a bunch of values
repeat (6) begin
read_word;
end

// *** Write a bunch more values
write_word (0,1,16'h0001);
write_word (0,1,16'h0002);
write_word (0,1,16'h0003);
write_word (0,1,16'h0004);
write_word (0,1,16'h0005);
write_word (0,1,16'h0006);
write_word (0,1,16'h0007);
write_word (0,1,16'h0008);

// ** Read a bunch of values
repeat (8) begin
read_word;
end

$display ("Done TEST1.");
end
endtask
 

//Test2
 

task test2;
reg [15:0] writer_counter;
begin
packet_in = {default:'z};
writer_counter = 16'h0001;
writep = 0;
readp = 0;

// Reset
rstp = 1;
#50;
rstp = 0;
#50;

fork
// Writer
begin
repeat (500) begin
@(negedge clk);
if (fullp == 1'b0) begin
write_word ($random,$random,$random);
#5;
writer_counter = writer_counter + 1;
end
else begin
$display ("WRITER is waiting..");
end
// Delay a random amount of time between 0ns and 100ns
#(50 + ($random % 50));
end
$display ("Done with WRITER fork..");
#200 $finish;
end

// Reader
begin
forever begin
@(negedge clk);
if (emptyp == 1'b0) begin
read_word;
end
else begin
$display ("READER is waiting..");
end
// Delay a random amount of time between 0ns and 100ns
#(50 + ($random % 50));
end
end
join
end
endtask

always @(fullp)
$display ("fullp = %0b", fullp);

always @(emptyp)
$display ("emptyp = %0b", emptyp);

always @(U1.head)
$display ("head = %0h", U1.head);

always @(U1.tail)
$display ("tail = %0h", U1.tail);

endmodule