Prompt:
module top_module (
	input [254:0] in,
	output reg [7:0] out
);

`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [254:0] in,
	output reg [7:0] out
);

	always_comb  begin
		out = 0;
		for (int i=0;i<255;i++)
			out = out + in[i];
	end

endmodule

module stimulus_gen (
	input clk,
	output logic [254:0] in,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable
);

// Add two ports to module stimulus_gen:
//    output [511:0] wavedrom_title
//    output reg wavedrom_enable

	task wavedrom_start(input[511:0] title = "");
	endtask

	task wavedrom_stop;
		#1;
	endtask

	initial begin
		in <= 255'h0;
		wavedrom_start("");
		@(posedge clk, negedge clk) in <= 255'h0;
		@(posedge clk, negedge clk) in <= 255'h0;
		@(posedge clk, negedge clk) in <= 255'h1;
		@(posedge clk, negedge clk) in <= 255'h1;
		@(posedge clk, negedge clk) in <= 255'h3;
		@(posedge clk, negedge clk) in <= 255'h3;
		@(posedge clk, negedge clk) in <= 255'h7;
		@(posedge clk, negedge clk) in <= 255'haaaa;
		@(posedge clk, negedge clk) in <= 255'hf00000;
		@(posedge clk, negedge clk) in <= 255'h0;
		wavedrom_stop();
		repeat (200) @(posedge clk, negedge clk) begin
			in <= {$random, $random, $random, $random, $random, $random, $random, $random};
		end
		@(posedge clk);
		in <= '0;
		@(posedge clk)
		in <= '1;
		@(posedge clk)
		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_out;
		int errortime_out;

		int clocks;
	} stats;

	stats stats1;

	wire[511:0] wavedrom_title;
	wire wavedrom_enable;
	int wavedrom_hide_after_time;

	reg clk=0;
	initial forever
		#5 clk = ~clk;

	logic [254:0] in;
	logic [7:0] out_ref;
	logic [7:0] out_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,in,out_ref,out_dut );
	end

	wire tb_match;		// Verification
	wire tb_mismatch = ~tb_match;

	stimulus_gen stim1 (
		.clk,
		.* ,
		.in );
	reference_module good1 (
		.in,
		.out(out_ref) );

	top_module top_module1 (
		.in,
		.out(out_dut) );

	bit strobe = 0;
	task wait_for_end_of_timestep;
		repeat(5) begin
			strobe <= !strobe;  // Try to delay until the very end of the time step.
			@(strobe);
		end
	endtask

	final begin
		if (stats1.errors_out) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out", stats1.errors_out, stats1.errortime_out);
		else $display("Hint: Output '%s' has no mismatches.", "out");

		$display("Hint: Total mismatched samples is %1d out of %1d samples\n", stats1.errors, stats1.clocks);
		$display("Simulation finished at %0d ps", $time);
		$display("Mismatches: %1d in %1d samples", stats1.errors, stats1.clocks);
	end

	// Verification: XORs on the right makes any X in good_vector match anything, but X in dut_vector will only match X.
	assign tb_match = ( { out_ref } === ( { out_ref } ^ { out_dut } ^ { out_ref } ) );
	// Use explicit sensitivity list here. @(*) causes NetProc::nex_input() to be called when trying to compute
	// the sensitivity list of the @(strobe) process, which isn't implemented.
	always @(posedge clk, negedge clk) begin

		stats1.clocks++;
		if (!tb_match) begin
			if (stats1.errors == 0) stats1.errortime = $time;
			stats1.errors++;
		end
		if (out_ref !== ( out_ref ^ out_dut ^ out_ref ))
		begin if (stats1.errors_out == 0) stats1.errortime_out = $time;
			stats1.errors_out = stats1.errors_out+1'b1; end

	end
endmodule


Prompt:
module top_module (
	input clk,
	input x,
	input [2:0] y,
	output reg Y0,
	output reg z
);

`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input x,
	input [2:0] y,
	output reg Y0,
	output reg z
);

	always_comb begin
		case ({y[2:0], x})
			4'h0: Y0 = 0;
			4'h1: Y0 = 1;
			4'h2: Y0 = 1;
			4'h3: Y0 = 0;
			4'h4: Y0 = 0;
			4'h5: Y0 = 1;
			4'h6: Y0 = 1;
			4'h7: Y0 = 0;
			4'h8: Y0 = 1;
			4'h9: Y0 = 0;
			default: Y0 = 1'bx;
		endcase

		case (y[2:0])
			3'h0: z = 0;
			3'h1: z = 0;
			3'h2: z = 0;
			3'h3: z = 1;
			3'h4: z = 1;
			default: z = 1'bx;
		endcase
	end

endmodule

module stimulus_gen (
	input clk,
	output logic x,
	output logic [2:0] y
);

	initial begin
		repeat(200) @(posedge clk, negedge clk) begin
			y <= $random;
			x <= $random;
		end

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_Y0;
		int errortime_Y0;
		int errors_z;
		int errortime_z;

		int clocks;
	} stats;

	stats stats1;

	wire[511:0] wavedrom_title;
	wire wavedrom_enable;
	int wavedrom_hide_after_time;

	reg clk=0;
	initial forever
		#5 clk = ~clk;

	logic x;
	logic [2:0] y;
	logic Y0_ref;
	logic Y0_dut;
	logic z_ref;
	logic z_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,x,y,Y0_ref,Y0_dut,z_ref,z_dut );
	end

	wire tb_match;		// Verification
	wire tb_mismatch = ~tb_match;

	stimulus_gen stim1 (
		.clk,
		.* ,
		.x,
		.y );
	reference_module good1 (
		.clk,
		.x,
		.y,
		.Y0(Y0_ref),
		.z(z_ref) );

	top_module top_module1 (
		.clk,
		.x,
		.y,
		.Y0(Y0_dut),
		.z(z_dut) );

	bit strobe = 0;
	task wait_for_end_of_timestep;
		repeat(5) begin
			strobe <= !strobe;  // Try to delay until the very end of the time step.
			@(strobe);
		end
	endtask

	final begin
		if (stats1.errors_Y0) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Y0", stats1.errors_Y0, stats1.errortime_Y0);
		else $display("Hint: Output '%s' has no mismatches.", "Y0");
		if (stats1.errors_z) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "z", stats1.errors_z, stats1.errortime_z);
		else $display("Hint: Output '%s' has no mismatches.", "z");

		$display("Hint: Total mismatched samples is %1d out of %1d samples\n", stats1.errors, stats1.clocks);
		$display("Simulation finished at %0d ps", $time);
		$display("Mismatches: %1d in %1d samples", stats1.errors, stats1.clocks);
	end

	// Verification: XORs on the right makes any X in good_vector match anything, but X in dut_vector will only match X.
	assign tb_match = ( { Y0_ref, z_ref } === ( { Y0_ref, z_ref } ^ { Y0_dut, z_dut } ^ { Y0_ref, z_ref } ) );
	// Use explicit sensitivity list here. @(*) causes NetProc::nex_input() to be called when trying to compute
	// the sensitivity list of the @(strobe) process, which isn't implemented.
	always @(posedge clk, negedge clk) begin

		stats1.clocks++;
		if (!tb_match) begin
			if (stats1.errors == 0) stats1.errortime = $time;
			stats1.errors++;
		end
		if (Y0_ref !== ( Y0_ref ^ Y0_dut ^ Y0_ref ))
		begin if (stats1.errors_Y0 == 0) stats1.errortime_Y0 = $time;
			stats1.errors_Y0 = stats1.errors_Y0+1'b1; end
		if (z_ref !== ( z_ref ^ z_dut ^ z_ref ))
		begin if (stats1.errors_z == 0) stats1.errortime_z = $time;
			stats1.errors_z = stats1.errors_z+1'b1; end

	end
endmodule


Prompt:
module top_module(
	input mode,
	input too_cold,
	input too_hot,
	input fan_on,
	output heater,
	output aircon,
	output fan
);

`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input mode,
	input too_cold,
	input too_hot,
	input fan_on,
	output heater,
	output aircon,
	output fan
);

	assign fan = (mode ? too_cold : too_hot) | fan_on;
	assign heater = (mode & too_cold);
	assign aircon = (~mode & too_hot);

endmodule

module stimulus_gen (
	input clk,
	output reg too_cold, too_hot, mode, fan_on,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable
);

// Add two ports to module stimulus_gen:
//    output [511:0] wavedrom_title
//    output reg wavedrom_enable

	task wavedrom_start(input[511:0] title = "");
	endtask

	task wavedrom_stop;
		#1;
	endtask

	initial begin
		{too_cold, too_hot, mode, fan_on} <= 4'b0010;
		@(negedge clk);
		wavedrom_start("Winter");
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0010;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0010;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1010;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1011;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0010;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0011;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0010;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0110;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1110;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0111;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1111;
		@(negedge clk) wavedrom_stop();

		{too_cold, too_hot, mode, fan_on} <= 4'b0000;
		@(negedge clk);
		wavedrom_start("Summer");
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0000;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0000;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0100;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0101;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0000;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0001;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b0000;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1000;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1100;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1001;
			@(posedge clk) {too_cold, too_hot, mode, fan_on} <= 4'b1101;
		@(negedge clk) wavedrom_stop();

		repeat(200)
			@(posedge clk, negedge clk) {too_cold, too_hot, mode, fan_on} <= $random;

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_heater;
		int errortime_heater;
		int errors_aircon;
		int errortime_aircon;
		int errors_fan;
		int errortime_fan;

		int clocks;
	} stats;

	stats stats1;

	wire[511:0] wavedrom_title;
	wire wavedrom_enable;
	int wavedrom_hide_after_time;

	reg clk=0;
	initial forever
		#5 clk = ~clk;

	logic mode;
	logic too_cold;
	logic too_hot;
	logic fan_on;
	logic heater_ref;
	logic heater_dut;
	logic aircon_ref;
	logic aircon_dut;
	logic fan_ref;
	logic fan_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,mode,too_cold,too_hot,fan_on,heater_ref,heater_dut,aircon_ref,aircon_dut,fan_ref,fan_dut );
	end

	wire tb_match;		// Verification
	wire tb_mismatch = ~tb_match;

	stimulus_gen stim1 (
		.clk,
		.* ,
		.mode,
		.too_cold,
		.too_hot,
		.fan_on );
	reference_module good1 (
		.mode,
		.too_cold,
		.too_hot,
		.fan_on,
		.heater(heater_ref),
		.aircon(aircon_ref),
		.fan(fan_ref) );

	top_module top_module1 (
		.mode,
		.too_cold,
		.too_hot,
		.fan_on,
		.heater(heater_dut),
		.aircon(aircon_dut),
		.fan(fan_dut) );

	bit strobe = 0;
	task wait_for_end_of_timestep;
		repeat(5) begin
			strobe <= !strobe;  // Try to delay until the very end of the time step.
			@(strobe);
		end
	endtask

	final begin
		if (stats1.errors_heater) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "heater", stats1.errors_heater, stats1.errortime_heater);
		else $display("Hint: Output '%s' has no mismatches.", "heater");
		if (stats1.errors_aircon) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "aircon", stats1.errors_aircon, stats1.errortime_aircon);
		else $display("Hint: Output '%s' has no mismatches.", "aircon");
		if (stats1.errors_fan) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "fan", stats1.errors_fan, stats1.errortime_fan);
		else $display("Hint: Output '%s' has no mismatches.", "fan");

		$display("Hint: Total mismatched samples is %1d out of %1d samples\n", stats1.errors, stats1.clocks);
		$display("Simulation finished at %0d ps", $time);
		$display("Mismatches: %1d in %1d samples", stats1.errors, stats1.clocks);
	end

	// Verification: XORs on the right makes any X in good_vector match anything, but X in dut_vector will only match X.
	assign tb_match = ( { heater_ref, aircon_ref, fan_ref } === ( { heater_ref, aircon_ref, fan_ref } ^ { heater_dut, aircon_dut, fan_dut } ^ { heater_ref, aircon_ref, fan_ref } ) );
	// Use explicit sensitivity list here. @(*) causes NetProc::nex_input() to be called when trying to compute
	// the sensitivity list of the @(strobe) process, which isn't implemented.
	always @(posedge clk, negedge clk) begin

		stats1.clocks++;
		if (!tb_match) begin
			if (stats1.errors == 0) stats1.errortime = $time;
			stats1.errors++;
		end
		if (heater_ref !== ( heater_ref ^ heater_dut ^ heater_ref ))
		begin if (stats1.errors_heater == 0) stats1.errortime_heater = $time;
			stats1.errors_heater = stats1.errors_heater+1'b1; end
		if (aircon_ref !== ( aircon_ref ^ aircon_dut ^ aircon_ref ))
		begin if (stats1.errors_aircon == 0) stats1.errortime_aircon = $time;
			stats1.errors_aircon = stats1.errors_aircon+1'b1; end
		if (fan_ref !== ( fan_ref ^ fan_dut ^ fan_ref ))
		begin if (stats1.errors_fan == 0) stats1.errortime_fan = $time;
			stats1.errors_fan = stats1.errors_fan+1'b1; end

	end
endmodule


Prompt:
module top_module (
	input [5:0] y,
	input w,
	output Y1,
	output Y3
);

`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [5:0] y,
	input w,
	output Y1,
	output Y3
);
	assign Y1 = y[0]&w;
	assign Y3 = (y[1]|y[2]|y[4]|y[5]) & ~w;

endmodule

module stimulus_gen (
	input clk,
	output logic[5:0] y,
	output logic w,
	input tb_match
);

	int errored1 = 0;
	int onehot_error = 0;
	int temp;

	initial begin
		// Test the one-hot cases first.
		repeat(200) @(posedge clk, negedge clk) begin
			y <= 1<< ($unsigned($random) % 6);
			w <= $random;
			if (!tb_match) onehot_error++;
		end

		// Random.
		errored1 = 0;
		repeat(400) @(posedge clk, negedge clk) begin
			do
				temp = $random;
			while ( !{temp[5:4],temp[2:1]} == !{temp[3],temp[0]} );
			// Make y[3,0] and y[5,4,2,1] mutually exclusive, so we can accept Y3=(~y[3] & ~y[0]) &~w as a valid answer too.

			y <= temp;
			w <= $random;
			if (!tb_match)
				errored1++;
		end
		if (!onehot_error && errored1)
			$display ("Hint: Your circuit passed when given only one-hot inputs, but not with semi-random inputs.");

		if (!onehot_error && errored1)
			$display("Hint: Are you doing something more complicated than deriving state transition equations by inspection?\n");

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_Y1;
		int errortime_Y1;
		int errors_Y3;
		int errortime_Y3;

		int clocks;
	} stats;

	stats stats1;

	wire[511:0] wavedrom_title;
	wire wavedrom_enable;
	int wavedrom_hide_after_time;

	reg clk=0;
	initial forever
		#5 clk = ~clk;

	logic [5:0] y;
	logic w;
	logic Y1_ref;
	logic Y1_dut;
	logic Y3_ref;
	logic Y3_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,y,w,Y1_ref,Y1_dut,Y3_ref,Y3_dut );
	end

	wire tb_match;		// Verification
	wire tb_mismatch = ~tb_match;

	stimulus_gen stim1 (
		.clk,
		.* ,
		.y,
		.w );
	reference_module good1 (
		.y,
		.w,
		.Y1(Y1_ref),
		.Y3(Y3_ref) );

	top_module top_module1 (
		.y,
		.w,
		.Y1(Y1_dut),
		.Y3(Y3_dut) );

	bit strobe = 0;
	task wait_for_end_of_timestep;
		repeat(5) begin
			strobe <= !strobe;  // Try to delay until the very end of the time step.
			@(strobe);
		end
	endtask

	final begin
		if (stats1.errors_Y1) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Y1", stats1.errors_Y1, stats1.errortime_Y1);
		else $display("Hint: Output '%s' has no mismatches.", "Y1");
		if (stats1.errors_Y3) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Y3", stats1.errors_Y3, stats1.errortime_Y3);
		else $display("Hint: Output '%s' has no mismatches.", "Y3");

		$display("Hint: Total mismatched samples is %1d out of %1d samples\n", stats1.errors, stats1.clocks);
		$display("Simulation finished at %0d ps", $time);
		$display("Mismatches: %1d in %1d samples", stats1.errors, stats1.clocks);
	end

	// Verification: XORs on the right makes any X in good_vector match anything, but X in dut_vector will only match X.
	assign tb_match = ( { Y1_ref, Y3_ref } === ( { Y1_ref, Y3_ref } ^ { Y1_dut, Y3_dut } ^ { Y1_ref, Y3_ref } ) );
	// Use explicit sensitivity list here. @(*) causes NetProc::nex_input() to be called when trying to compute
	// the sensitivity list of the @(strobe) process, which isn't implemented.
	always @(posedge clk, negedge clk) begin

		stats1.clocks++;
		if (!tb_match) begin
			if (stats1.errors == 0) stats1.errortime = $time;
			stats1.errors++;
		end
		if (Y1_ref !== ( Y1_ref ^ Y1_dut ^ Y1_ref ))
		begin if (stats1.errors_Y1 == 0) stats1.errortime_Y1 = $time;
			stats1.errors_Y1 = stats1.errors_Y1+1'b1; end
		if (Y3_ref !== ( Y3_ref ^ Y3_dut ^ Y3_ref ))
		begin if (stats1.errors_Y3 == 0) stats1.errortime_Y3 = $time;
			stats1.errors_Y3 = stats1.errors_Y3+1'b1; end

	end
endmodule