Subversion Repositories a-z80

//--------------------------------------------------------------
// Testbench for the top level design
//--------------------------------------------------------------
`include "z80.svh"

module test_bench_top(z80_if.tb z);

assign clk = z.CLK;

initial begin : init
    $display("Test: Start of test at %d", $time);
    z.nWAIT <= `CLR;
    z.nINT <= `CLR;
    z.nNMI <= `CLR;
    z.nBUSRQ <= `CLR;
    z.nRESET <= `SET;
#2  repeat (3) @(posedge clk);
    z.nRESET <= `CLR;
end : init

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Testbench for interrupt testing
// Enable one or more interrupt generators and run them with the
// 'hello world' code
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// Infuse a NMI at a certain clock
initial begin : nmi_once
    repeat (500) @(posedge clk);
//    z.nNMI <= `SET;
    repeat (1) @(posedge clk);
    z.nNMI <= `CLR;
end : nmi_once

// Test sending a *periodic* NMI
always begin : nmi_rep
    repeat (3000) @(posedge clk);
//    z.nNMI <= `SET;
    repeat (1) @(posedge clk);
    z.nNMI <= `CLR;
end : nmi_rep

// Infuse an INT at a certain clock
initial begin : int_once
    repeat (1000) @(posedge clk);
//    z.nINT <= `SET;
    repeat (300) @(posedge clk);
    z.nINT <= `CLR;
end : int_once

// Test sending a *periodic* INT
always begin : int_rep
    repeat (5000) @(posedge clk);
//    z.nINT <= `SET;
    repeat (300) @(posedge clk);
    z.nINT <= `CLR;
end : int_rep

// Test WAIT.. inject at will
initial begin : wait_once
    repeat (1008) @(posedge clk);
//    z.nWAIT <= `SET;
    repeat (2) @(posedge clk);
    z.nWAIT <= `CLR;
end : wait_once

// Test BUSRQ / BUSACK
initial begin : busrq_once
    repeat (10) @(posedge clk);
//    z.nBUSRQ <= `SET;
    repeat (10) @(posedge clk);
    z.nBUSRQ <= `CLR;
end : busrq_once

// Test special RESET
initial begin : spc_reset
    repeat (40) @(posedge clk);
//    z.nRESET <= `SET;
    repeat (1) @(posedge clk);
    z.nRESET <= `CLR;
end : spc_reset

endmodule

module test_top();

// Although the clock is going forever, we will stop simulation at some point
bit clk = 1;
initial forever #1 clk = ~clk;

// Stop after printing "Hello, World!"
initial begin : stopme
    #70000 $stop();
end : stopme

z80_if z80(clk);            // Instantiate the Z80 bus interface
z80_top_ifc_n dut(z80);     // Create an instance of our Z80 design
test_bench_top tb(z80);     // Create an instance of the test bench

ram  ram( .Address(z80.A), .Data(z80.D), .CS(z80.nMREQ), .WE(z80.nWR), .OE(z80.nRD) );
io   io( .Address(z80.A), .Data(z80.D), .CS(z80.nIORQ), .WE(z80.nWR), .OE(z80.nRD) );
iorq iorq( .Data(z80.D), .M1(z80.nM1), .IORQ(z80.nIORQ) );

endmodule