prompt:
module top_module (
	input [99:0] a,
	input [99:0] b,
	input sel,
	output [99:0] out
);

canonical_solution:
	assign out = sel ? b : a;

endmodule

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [99:0] a,
	input [99:0] b,
	input sel,
	output [99:0] out
);

	assign out = sel ? b : a;

endmodule

module stimulus_gen (
	input clk,
	output logic [99:0] a,b,
	output logic sel,
	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
		a <= 'hdeadbeef;
		b <= 'h5eaf00d;
		sel <= 0;
		@(negedge clk);
		wavedrom_start("Beef or seafood?");
			repeat(6) @(posedge clk) sel <= ~sel;
		@(negedge clk);
		wavedrom_stop();
		repeat(100) @(posedge clk, negedge clk)
			{a,b,sel} <= {$random, $random, $random, $random, $random, $random, $random};
		$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 [99:0] a;
	logic [99:0] b;
	logic sel;
	logic [99:0] out_ref;
	logic [99:0] out_dut;

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

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.a,
		.b,
		.sel );
	reference_module good1 (
		.a,
		.b,
		.sel,
		.out(out_ref) );

	top_module top_module1 (
		.a,
		.b,
		.sel,
		.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

simple_description: This module assigns the output to either input a or b depending on the value of the select signal.

detail_description: This module is a simple multiplexer that takes two inputs a and b, and a select signal sel. Depending on the value of sel, the output out will be either a or b. If sel is 0, then out will be equal to a, and if sel is 1, then out will be equal to b. This module is useful for selecting between two different inputs depending on the value of the select signal.


prompt:
module top_module(
	input [3:1] y,
	input w,
	output reg Y2);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input [3:1] y,
	input w,
	output reg Y2);

	always_comb begin
		case ({y, w})
			4'h0: Y2 = 1'b0;
			4'h1: Y2 = 1'b0;
			4'h2: Y2 = 1'b1;
			4'h3: Y2 = 1'b1;
			4'h4: Y2 = 1'b0;
			4'h5: Y2 = 1'b1;
			4'h6: Y2 = 1'b0;
			4'h7: Y2 = 1'b0;
			4'h8: Y2 = 1'b0;
			4'h9: Y2 = 1'b1;
			4'ha: Y2 = 1'b1;
			4'hb: Y2 = 1'b1;
			default: Y2 = 1'bx;
		endcase
	end

endmodule

module stimulus_gen (
	input clk,
	output reg [3:1] y,
	output reg w
);

	initial begin
		repeat(100) @(posedge clk, negedge clk) begin
			{y,w} <= $random;
		end

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_Y2;
		int errortime_Y2;

		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 [3:1] y;
	logic w;
	logic Y2_ref;
	logic Y2_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,y,w,Y2_ref,Y2_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.y,
		.w );
	reference_module good1 (
		.y,
		.w,
		.Y2(Y2_ref) );

	top_module top_module1 (
		.y,
		.w,
		.Y2(Y2_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_Y2) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Y2", stats1.errors_Y2, stats1.errortime_Y2);
		else $display("Hint: Output '%s' has no mismatches.", "Y2");

		$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 = ( { Y2_ref } === ( { Y2_ref } ^ { Y2_dut } ^ { Y2_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 (Y2_ref !== ( Y2_ref ^ Y2_dut ^ Y2_ref ))
		begin if (stats1.errors_Y2 == 0) stats1.errortime_Y2 = $time;
			stats1.errors_Y2 = stats1.errors_Y2+1'b1; end

	end
endmodule

detail_description:
The module has 3 inputs. y input is a 4 bits input, w is a 1 bit input, Y2 is a 1 bit reg output.
It is an always_comb block, not an always_ff block.
So there is no state transitions and clock.
Every time a new input comes, the output will be changed immediately.

It is a case statement, the left hand side is a combination of inputs(y, w).
The right hand side is the output(Y2).
If the input is 4'h0, the output will be 0.
If the input is 4'h1, the output will be 0.
If the input is 4'h2, the output will be 1.
If the input is 4'h3, the output will be 1.
If the input is 4'h4, the output will be 0.
If the input is 4'h5, the output will be 1.
If the input is 4'h6, the output will be 0.
If the input is 4'h7, the output will be 0.
If the input is 4'h8, the output will be 0.
If the input is 4'h9, the output will be 1.
If the input is 4'ha, the output will be 1.
If the input is 4'hb, the output will be 1.


task_id: ringer

prompt:
module top_module(
	input ring,
	input vibrate_mode,
	output ringer,
	output motor
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input ring,
	input vibrate_mode,
	output ringer,
	output motor
);

	assign ringer = ring & ~vibrate_mode;
	assign motor = ring & vibrate_mode;

endmodule

module stimulus_gen (
	input clk,
	output reg ring, vibrate_mode,
	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
		int count; count = 0;
		{vibrate_mode,ring} <= 1'b0;
		wavedrom_start();
		repeat(10) @(posedge clk)
			{vibrate_mode,ring} <= count++;
		wavedrom_stop();

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_ringer;
		int errortime_ringer;
		int errors_motor;
		int errortime_motor;

		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 ring;
	logic vibrate_mode;
	logic ringer_ref;
	logic ringer_dut;
	logic motor_ref;
	logic motor_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,ring,vibrate_mode,ringer_ref,ringer_dut,motor_ref,motor_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.ring,
		.vibrate_mode );
	reference_module good1 (
		.ring,
		.vibrate_mode,
		.ringer(ringer_ref),
		.motor(motor_ref) );

	top_module top_module1 (
		.ring,
		.vibrate_mode,
		.ringer(ringer_dut),
		.motor(motor_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_ringer) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "ringer", stats1.errors_ringer, stats1.errortime_ringer);
		else $display("Hint: Output '%s' has no mismatches.", "ringer");
		if (stats1.errors_motor) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "motor", stats1.errors_motor, stats1.errortime_motor);
		else $display("Hint: Output '%s' has no mismatches.", "motor");

		$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 = ( { ringer_ref, motor_ref } === ( { ringer_ref, motor_ref } ^ { ringer_dut, motor_dut } ^ { ringer_ref, motor_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 (ringer_ref !== ( ringer_ref ^ ringer_dut ^ ringer_ref ))
		begin if (stats1.errors_ringer == 0) stats1.errortime_ringer = $time;
			stats1.errors_ringer = stats1.errors_ringer+1'b1; end
		if (motor_ref !== ( motor_ref ^ motor_dut ^ motor_ref ))
		begin if (stats1.errors_motor == 0) stats1.errortime_motor = $time;
			stats1.errors_motor = stats1.errors_motor+1'b1; end

	end
endmodule

simple_description: This module assigns the ringer output to the logical AND of the ring and vibrate_mode inputs, and the motor output to the logical AND of the ring and vibrate_mode inputs.

detail_description: This Verilog module is a top-level module that controls the ringer and motor of a device. It has four ports: two inputs (ring and vibrate_mode) and two outputs (ringer and motor).   The ring input is a signal that is used to indicate when the device should be ringing or vibrating. The vibrate_mode input is a signal that indicates whether the device should be ringing or vibrating.   The ringer output is a signal that is used to control the ringer of the device. It is set to 1 when the device should be ringing and 0 when it should not be ringing. The motor output is a signal that is used to control the motor of the device. It is set to 1 when the device should be vibrating and 0 when it should not be vibrating.   The module uses two assign statements to control the ringer and motor outputs. The first assign statement sets the ringer output to the logical AND of the ring and the logical NOT of the vibrate_mode inputs. This means that the ringer output will be set to 1 when the ring input is 1 and the vibrate_mode input is 0, and it will be set to 0 otherwise.   The second assign statement sets the motor output to the logical AND of the ring and the vibrate_mode inputs. This means that the motor output will be set to 1 when both the ring input and the vibrate_mode input are 1, and it will be set to 0 otherwise.   This module is used to control the ringer and motor of a device based on the ring and vibrate_mode inputs. When the ring input is 1 and the vibrate_mode input is 0, the ringer output will be set to 1 and the motor output will be set to 0. When the ring input is 1 and the vibrate_mode input is 1, the ringer output will be set to 0 and the motor output will be set to 1.


prompt:
module top_module(
	input a,
	input b,
	output out_assign,
	output reg out_alwaysblock
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input a,
	input b,
	output out_assign,
	output reg out_alwaysblock
);

	assign out_assign = a & b;
	always @(*) out_alwaysblock = a & b;

endmodule

module stimulus_gen (
	input clk,
	output reg a, b,
	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
		int count; count = 0;
		{a,b} <= 1'b0;
		wavedrom_start("AND gate");
		repeat(10) @(posedge clk)
			{a,b} <= count++;
		wavedrom_stop();

		repeat(200) @(posedge clk, negedge clk)
			{b,a} <= $random;

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_out_assign;
		int errortime_out_assign;
		int errors_out_alwaysblock;
		int errortime_out_alwaysblock;

		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 a;
	logic b;
	logic out_assign_ref;
	logic out_assign_dut;
	logic out_alwaysblock_ref;
	logic out_alwaysblock_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,a,b,out_assign_ref,out_assign_dut,out_alwaysblock_ref,out_alwaysblock_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.a,
		.b );
	reference_module good1 (
		.a,
		.b,
		.out_assign(out_assign_ref),
		.out_alwaysblock(out_alwaysblock_ref) );

	top_module top_module1 (
		.a,
		.b,
		.out_assign(out_assign_dut),
		.out_alwaysblock(out_alwaysblock_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_assign) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_assign", stats1.errors_out_assign, stats1.errortime_out_assign);
		else $display("Hint: Output '%s' has no mismatches.", "out_assign");
		if (stats1.errors_out_alwaysblock) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_alwaysblock", stats1.errors_out_alwaysblock, stats1.errortime_out_alwaysblock);
		else $display("Hint: Output '%s' has no mismatches.", "out_alwaysblock");

		$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_assign_ref, out_alwaysblock_ref } === ( { out_assign_ref, out_alwaysblock_ref } ^ { out_assign_dut, out_alwaysblock_dut } ^ { out_assign_ref, out_alwaysblock_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_assign_ref !== ( out_assign_ref ^ out_assign_dut ^ out_assign_ref ))
		begin if (stats1.errors_out_assign == 0) stats1.errortime_out_assign = $time;
			stats1.errors_out_assign = stats1.errors_out_assign+1'b1; end
		if (out_alwaysblock_ref !== ( out_alwaysblock_ref ^ out_alwaysblock_dut ^ out_alwaysblock_ref ))
		begin if (stats1.errors_out_alwaysblock == 0) stats1.errortime_out_alwaysblock = $time;
			stats1.errors_out_alwaysblock = stats1.errors_out_alwaysblock+1'b1; end

	end
endmodule

simple_description: This module assigns the output of a logical AND operation between inputs a and b to two outputs, out_assign and out_alwaysblock.

detail_description: This Verilog module is used to perform a logical AND operation between two input signals, a and b, and output the result to two different outputs, out_assign and out_alwaysblock. The module has two input signals, a and b, and two output signals, out_assign and out_alwaysblock.   The first output, out_assign, is generated using an assign statement, which assigns the result of the logical AND operation between a and b to out_assign. The second output, out_alwaysblock, is generated using an always block. The always block contains a sensitivity list, which is set to '*', meaning that the block will be triggered whenever any of the variables in the sensitivity list changes. The always block assigns the result of the logical AND operation between a and b to out_alwaysblock.   In summary, this Verilog module performs a logical AND operation between two input signals, a and b, and outputs the result to two different outputs, out_assign and out_alwaysblock.


task_id: zero

prompt:
module top_module(
	output zero);

canonical_solution:
	assign zero = 1'b0;

endmodule

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	output zero);

	assign zero = 1'b0;

endmodule

module stimulus_gen (
	input clk,
	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
		wavedrom_start("Output should 0");
		repeat(20) @(posedge clk, negedge clk);
		wavedrom_stop();

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_zero;
		int errortime_zero;

		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 zero_ref;
	logic zero_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,zero_ref,zero_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.*  );
	reference_module good1 (
		.zero(zero_ref) );

	top_module top_module1 (
		.zero(zero_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_zero) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "zero", stats1.errors_zero, stats1.errortime_zero);
		else $display("Hint: Output '%s' has no mismatches.", "zero");

		$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 = ( { zero_ref } === ( { zero_ref } ^ { zero_dut } ^ { zero_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 (zero_ref !== ( zero_ref ^ zero_dut ^ zero_ref ))
		begin if (stats1.errors_zero == 0) stats1.errortime_zero = $time;
			stats1.errors_zero = stats1.errors_zero+1'b1; end

	end
endmodule

simple_description: This module assigns the output 'zero' to a logic value of 0.

detail_description: This top Verilog module is a simple module that assigns the output zero to a value of 0. This module does not have any inputs and is used to assign a constant value to the output. This module is useful when a constant value is needed for a design. For example, if a design requires a signal to be always 0, this module can be used to assign the output zero to 0. This module can also be used to assign a constant value to a signal that is used as an input to another module.


prompt:
module top_module (
	input clk,
	input a,
	output reg q
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input a,
	output reg q
);

	always @(posedge clk)
		q <= ~a;

endmodule

module stimulus_gen (
	input clk,
	output logic a,
	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
		@(posedge clk) {a} <= 0;
		@(negedge clk) wavedrom_start("Unknown circuit");
			@(posedge clk) {a} <= 0;
			repeat(10) @(posedge clk) a <= $urandom;
		wavedrom_stop();

		repeat(100) @(posedge clk, negedge clk)
			a <= $urandom;
		$finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_q;
		int errortime_q;

		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 a;
	logic q_ref;
	logic q_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,a,q_ref,q_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.a );
	reference_module good1 (
		.clk,
		.a,
		.q(q_ref) );

	top_module top_module1 (
		.clk,
		.a,
		.q(q_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_q) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "q", stats1.errors_q, stats1.errortime_q);
		else $display("Hint: Output '%s' has no mismatches.", "q");

		$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 = ( { q_ref } === ( { q_ref } ^ { q_dut } ^ { q_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 (q_ref !== ( q_ref ^ q_dut ^ q_ref ))
		begin if (stats1.errors_q == 0) stats1.errortime_q = $time;
			stats1.errors_q = stats1.errors_q+1'b1; end

	end
endmodule

simple_description: This module creates an output q that is the inverse of the input a on the rising edge of the clock signal clk.

detail_description: This Verilog module is a simple combinational logic circuit that has one input (a) and one output (q). It is triggered by a clock signal (clk) and has a register (q) that stores the output value. The module uses a positive edge triggered always block to implement the logic. When the clock signal goes from low to high, the output q is set to the inverse of the input a. This means that when the input a is high, the output q will be low and vice versa. The module will continuously update the output q whenever the clock signal changes from low to high.


prompt:
module top_module (
	input clk,
	input areset,
	input x,
	output z
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input areset,
	input x,
	output z
);

	parameter A=0,B=1,C=2;
	reg [1:0] state;
	always @(posedge clk, posedge areset) begin
		if (areset)
			state <= A;
		else begin
			case (state)
				A: state <= x ? C : A;
				B: state <= x ? B : C;
				C: state <= x ? B : C;
			endcase
		end
	end

	assign z = (state == C);

endmodule

module stimulus_gen (
	input clk,
	output logic x,
	output logic areset,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable,
	input tb_match
);
	reg reset;
	assign areset = reset;

// 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

	task reset_test(input async=0);
		bit arfail, srfail, datafail;

		@(posedge clk);
		@(posedge clk) reset <= 0;
		repeat(3) @(posedge clk);

		@(negedge clk) begin datafail = !tb_match ; reset <= 1; end
		@(posedge clk) arfail = !tb_match;
		@(posedge clk) begin
			srfail = !tb_match;
			reset <= 0;
		end
		if (srfail)
			$display("Hint: Your reset doesn't seem to be working.");
		else if (arfail && (async || !datafail))
			$display("Hint: Your reset should be %0s, but doesn't appear to be.", async ? "asynchronous" : "synchronous");
		// Don't warn about synchronous reset if the half-cycle before is already wrong. It's more likely
		// a functionality error than the reset being implemented asynchronously.

	endtask

	initial begin
		x <= 0;
		reset <= 1;
		@(posedge clk) reset <= 0; x <= 1;
		@(posedge clk) x <= 0;
		reset_test(1);

		@(negedge clk) wavedrom_start();
			@(posedge clk) {reset,x} <= 2'h2;
			@(posedge clk) {reset,x} <= 2'h0;
			@(posedge clk) {reset,x} <= 2'h0;
			@(posedge clk) {reset,x} <= 2'h1;
			@(posedge clk) {reset,x} <= 2'h0;
			@(posedge clk) {reset,x} <= 2'h1;
			@(posedge clk) {reset,x} <= 2'h1;
			@(posedge clk) {reset,x} <= 2'h0;
			@(posedge clk) {reset,x} <= 2'h0;
		@(negedge clk) wavedrom_stop();
		repeat(400) @(posedge clk, negedge clk)
			{reset,x} <= {($random&31) == 0, ($random&1)==0 };

		$finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		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 areset;
	logic x;
	logic z_ref;
	logic z_dut;

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

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.areset,
		.x );
	reference_module good1 (
		.clk,
		.areset,
		.x,
		.z(z_ref) );

	top_module top_module1 (
		.clk,
		.areset,
		.x,
		.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_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 = ( { z_ref } === ( { z_ref } ^ { z_dut } ^ { 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 (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

simple_description: This module is a state machine that outputs a '1' when the state is C, depending on the input 'x'.

detail_description: The top Verilog module is a state machine that takes in three inputs (clk, areset, and x) and outputs one output (z). The module has a parameter A, B, and C which are used to define the state of the machine. The state of the machine is stored in a register with two bits.   The module has an always block that is triggered on the positive edge of the clock and the reset signal. If the reset signal is triggered, the state of the machine is set to A. If the reset signal is not triggered, the state of the machine is determined by a case statement. If the state is A, the state is set to C if x is true, otherwise it stays at A. If the state is B, the state is set to B if x is true, otherwise it is set to C. If the state is C, the state is set to B if x is true, otherwise it is set to C.   The output of the module is determined by the state of the machine. If the state is C, the output is set to true, otherwise it is set to false.


prompt:
module top_module (
	input clk,
	input in,
	input areset,
	output out
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input in,
	input areset,
	output out
);
	parameter A=0, B=1, C=2, D=3;
	reg [1:0] state;
	reg [1:0] next;

    always_comb begin
		case (state)
			A: next = in ? B : A;
			B: next = in ? B : C;
			C: next = in ? D : A;
			D: next = in ? B : C;
		endcase
    end

    always @(posedge clk, posedge areset) begin
		if (areset) state <= A;
        else state <= next;
	end

	assign out = (state==D);

endmodule

module stimulus_gen (
	input clk,
	output logic in,
	output logic areset,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable,
	input tb_match
);
	reg reset;
	assign areset = reset;
	task reset_test(input async=0);
		bit arfail, srfail, datafail;

		@(posedge clk);
		@(posedge clk) reset <= 0;
		repeat(3) @(posedge clk);

		@(negedge clk) begin datafail = !tb_match ; reset <= 1; end
		@(posedge clk) arfail = !tb_match;
		@(posedge clk) begin
			srfail = !tb_match;
			reset <= 0;
		end
		if (srfail)
			$display("Hint: Your reset doesn't seem to be working.");
		else if (arfail && (async || !datafail))
			$display("Hint: Your reset should be %0s, but doesn't appear to be.", async ? "asynchronous" : "synchronous");
		// Don't warn about synchronous reset if the half-cycle before is already wrong. It's more likely
		// a functionality error than the reset being implemented asynchronously.

	endtask

// 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
		reset <= 1;
		in <= 0;
		@(posedge clk) reset <= 0; in <= 1;
		@(posedge clk) in <= 0;
		@(posedge clk) in <= 1;
		wavedrom_start();
			@(posedge clk) in <= 0;
			@(posedge clk) in <= 1;
			@(posedge clk);
			@(negedge clk) reset <= 1;
			@(posedge clk) reset <= 0;
			@(posedge clk) in <= 1;
			@(posedge clk) in <= 1;
			@(posedge clk) in <= 0;
			@(posedge clk) in <= 1;
			@(posedge clk) in <= 0;
			@(posedge clk) in <= 1;
			@(posedge clk) in <= 1;
			@(posedge clk) in <= 1;
		@(negedge clk);
		wavedrom_stop();
		repeat(200) @(posedge clk, negedge clk) begin
			in <= $random;
			reset <= !($random & 31);
		end

		#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 in;
	logic areset;
	logic out_ref;
	logic out_dut;

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

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

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

	top_module top_module1 (
		.clk,
		.in,
		.areset,
		.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

simple_description: This module is a state machine that outputs a signal when it reaches state D based on the input signal.

detail_description: This Verilog module implements a state machine with four states, A, B, C, and D. The state machine is triggered by the clock signal, clk, and the input signal, in. The output signal, out, is set to 1 when the state machine is in state D. The state machine is reset to state A when the reset signal, areset, is triggered.   The state machine is implemented using a 2-bit register, state, and a combinational logic block. The combinational logic block is used to determine the next state of the state machine based on the current state and the input signal. The logic is as follows:   If the current state is A, then the next state will be B if the input signal is 1, and A if the input signal is 0.   If the current state is B, then the next state will be B if the input signal is 1, and C if the input signal is 0.   If the current state is C, then the next state will be D if the input signal is 1, and A if the input signal is 0.   If the current state is D, then the next state will be B if the input signal is 1, and C if the input signal is 0.   The state register is updated on the rising edge of the clock signal, clk, and is reset to state A on the rising edge of the reset signal, areset. The output signal, out, is set to 1 when the state machine is in state D.


prompt:
module top_module (
	input [31:0] in,
	output [31:0] out
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [31:0] in,
	output [31:0] out
);

	assign out = {in[7:0], in[15:8], in[23:16], in[31:24]};

endmodule

module stimulus_gen (
	input clk,
	output logic [31:0] 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
		wavedrom_start("Random inputs");
		repeat(10) @(posedge clk, negedge clk)
			in <= $random;
		wavedrom_stop();
		repeat(100) @(posedge clk, negedge clk)
			in <= $random;
		$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 [31:0] in;
	logic [31:0] out_ref;
	logic [31:0] 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

simple_description: The top Verilog module takes an input of 32 bits and outputs the same 32 bits in a different order.

detail_description: This top module is a simple Verilog module that takes an input of 32 bits and outputs the same 32 bits in a different order. The module assigns the output to be the input bits rearranged in 8-bit chunks. The first 8 bits of the input are assigned to the first 8 bits of the output, the second 8 bits of the input are assigned to the second 8 bits of the output, and so on. This module is useful for rearranging the order of bits in a data stream.


prompt:
module top_module (
	input clk,
	input d,
	input r,
	output logic q
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input d,
	input r,
	output logic q
);

	always@(posedge clk) begin
		if (r)
			q <= 0;
		else
			q <= d;
	end

endmodule

module stimulus_gen (
	input clk,
	output logic d, r
);

	initial begin
		repeat(100) @(posedge clk, negedge clk) begin
			{d,r} <= $random;
		end

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_q;
		int errortime_q;

		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 d;
	logic r;
	logic q_ref;
	logic q_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,d,r,q_ref,q_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.d,
		.r );
	reference_module good1 (
		.clk,
		.d,
		.r,
		.q(q_ref) );

	top_module top_module1 (
		.clk,
		.d,
		.r,
		.q(q_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_q) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "q", stats1.errors_q, stats1.errortime_q);
		else $display("Hint: Output '%s' has no mismatches.", "q");

		$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 = ( { q_ref } === ( { q_ref } ^ { q_dut } ^ { q_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 (q_ref !== ( q_ref ^ q_dut ^ q_ref ))
		begin if (stats1.errors_q == 0) stats1.errortime_q = $time;
			stats1.errors_q = stats1.errors_q+1'b1; end

	end
endmodule

simple_description: This module is a basic D-type flip-flop that stores the value of the input d when the clock signal clk is high and the reset signal r is low.

detail_description: This Verilog module is a simple register that is used to store data. It has three inputs: a clock (clk), a data input (d), and a reset (r). It also has one output, q, which is the output of the register.   The module is triggered on the rising edge of the clock. When the reset is active, the output of the register is set to 0. Otherwise, the output is set to the value of the data input. This allows the register to store the data input until the reset is activated.


prompt:
module top_module(
	input x,
	input y,
	output z);

canonical_solution:
	assign z = (x^y) & x;

endmodule

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input x,
	input y,
	output z);

	assign z = (x^y) & x;

endmodule

module stimulus_gen (
	input clk,
	output logic x,
	output logic y
);

	always @(posedge clk, negedge clk)
		{x, y} <= $random % 4;

	initial begin
		repeat(101) @(negedge clk);
		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		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 y;
	logic z_ref;
	logic z_dut;

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

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

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

	top_module top_module1 (
		.x,
		.y,
		.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_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 = ( { z_ref } === ( { z_ref } ^ { z_dut } ^ { 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 (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

simple_description: This module assigns the output z to the bitwise XOR of x and y, ANDed with x.

detail_description: This top module is a simple combinational logic circuit that takes two inputs, x and y, and produces one output, z. The output z is the result of a logical AND operation between the exclusive OR (XOR) of the two inputs and the first input x. In other words, the output z will be high (1) if either x or y is high (1) but not both, and will be low (0) if both x and y are either high (1) or low (0). This is a useful circuit for implementing a 2-input multiplexer.


prompt:
module top_module(
	input clk,
	input load,
	input ena,
	input [1:0] amount,
	input [63:0] data,
	output reg [63:0] q);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input clk,
	input load,
	input ena,
	input [1:0] amount,
	input [63:0] data,
	output reg [63:0] q);

	always @(posedge clk) begin
		if (load)
			q <= data;
		else if (ena) case (amount)
			2'b00: q <= {q[62:0], 1'b0};
			2'b01: q <= {q[55:0], 8'b0};
			2'b10: q <= {q[63], q[63:1]};
			2'b11: q <= {{8{q[63]}}, q[63:8]};
			default: q <= 64'hx;
		endcase
	end
endmodule

module stimulus_gen (
	input clk,
	output reg load,
	output reg ena,
	output reg[1:0] amount,
	output reg[63:0] data,
	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
		load <= 1;
		ena <= 0;
		data <= 'x;
		amount <= 0;
		@(posedge clk) data <= 64'h000100;
		wavedrom_start("Shifting");
			@(posedge clk) load <= 0; ena <= 1;
							amount <= 2;
			@(posedge clk) amount <= 2;
			@(posedge clk) amount <= 2;
			@(posedge clk) amount <= 1;
			@(posedge clk) amount <= 1;
			@(posedge clk) amount <= 0;
			@(posedge clk) amount <= 0;
			@(posedge clk) amount <= 3;
			@(posedge clk) amount <= 3;
			@(posedge clk) amount <= 2;
			@(posedge clk) amount <= 2;
			@(negedge clk);
		wavedrom_stop();

		@(posedge clk); load <= 1; data <= 64'hx;
		@(posedge clk); load <= 1; data <= 64'h80000000_00000000;
		wavedrom_start("Arithmetic right shift");
			@(posedge clk) load <= 0; ena <= 1;
							amount <= 2;
			@(posedge clk) amount <= 2;
			@(posedge clk) amount <= 2;
			@(posedge clk) amount <= 2;
			@(posedge clk) amount <= 2;
			@(negedge clk);
		wavedrom_stop();

		@(posedge clk);
		@(posedge clk);

		repeat(4000) @(posedge clk, negedge clk) begin
			load <= !($random & 31);
			ena <= |($random & 15);
			amount <= $random;
			data <= {$random,$random};
		end
		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_q;
		int errortime_q;

		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 load;
	logic ena;
	logic [1:0] amount;
	logic [63:0] data;
	logic [63:0] q_ref;
	logic [63:0] q_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,load,ena,amount,data,q_ref,q_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.load,
		.ena,
		.amount,
		.data );
	reference_module good1 (
		.clk,
		.load,
		.ena,
		.amount,
		.data,
		.q(q_ref) );

	top_module top_module1 (
		.clk,
		.load,
		.ena,
		.amount,
		.data,
		.q(q_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_q) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "q", stats1.errors_q, stats1.errortime_q);
		else $display("Hint: Output '%s' has no mismatches.", "q");

		$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 = ( { q_ref } === ( { q_ref } ^ { q_dut } ^ { q_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 (q_ref !== ( q_ref ^ q_dut ^ q_ref ))
		begin if (stats1.errors_q == 0) stats1.errortime_q = $time;
			stats1.errors_q = stats1.errors_q+1'b1; end

	end
endmodule

detail_description:
The top module has 8 inputs and 2 outputs.

The inputs are:
- clk
- load
- ena
- amount[1:0]
- data[63:0]

The outputs are:
- q[63:0]

The top module has 1 always block.

The block is triggered by a rising edge of clk.

The always block has 1 if block.

The if block has a condition load and an else if block.

The else if block has a condition ena and 1 case block.

The case block has 4 case items, 00, 01, 10, 11, and 1 default item.

The case item 00 has 1 assignment.

The assignment is q = {q[62:0], 1'b0}

The case item 01 has 1 assignment.

The assignment is q = {q[55:0], 8'b0}

The case item 10 has 1 assignment.

The assignment is q = {q[63], q[63:1]}

The case item 11 has 1 assignment.

The assignment is q = {{8{q[63]}}, q[63:8]}

The default item has 1 assignment.

The assignment is q = 64'hx


prompt:
module top_module (
	input clk,
	input aresetn,
	input x,
	output reg z
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input aresetn,
	input x,
	output reg z
);
	parameter S=0, S1=1, S10=2;
	reg[1:0] state, next;

	always@(posedge clk, negedge aresetn)
		if (!aresetn)
			state <= S;
		else
			state <= next;

	always_comb begin
		case (state)
			S: next = x ? S1 : S;
			S1: next = x ? S1 : S10;
			S10: next = x ? S1 : S;
			default: next = 'x;
		endcase
	end

	always_comb begin
		case (state)
			S: z = 0;
			S1: z = 0;
			S10: z = x;
			default: z = 'x;
		endcase
	end

endmodule

module stimulus_gen (
	input clk,
	output logic aresetn,
	output logic x,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable,
	input tb_match
);
	reg reset;
	assign aresetn = ~reset;

// 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

	task reset_test(input async=0);
		bit arfail, srfail, datafail;

		@(posedge clk);
		@(posedge clk) reset <= 0;
		repeat(3) @(posedge clk);

		@(negedge clk) begin datafail = !tb_match ; reset <= 1; end
		@(posedge clk) arfail = !tb_match;
		@(posedge clk) begin
			srfail = !tb_match;
			reset <= 0;
		end
		if (srfail)
			$display("Hint: Your reset doesn't seem to be working.");
		else if (arfail && (async || !datafail))
			$display("Hint: Your reset should be %0s, but doesn't appear to be.", async ? "asynchronous" : "synchronous");
		// Don't warn about synchronous reset if the half-cycle before is already wrong. It's more likely
		// a functionality error than the reset being implemented asynchronously.

	endtask

	initial begin
		x <= 0;
		repeat(3) @(posedge clk);
		@(posedge clk) x <= 1;
		@(posedge clk) x <= 0;
		@(posedge clk) x <= 1;
	end

	initial begin
		reset <= 1;
		@(posedge clk) reset <= 0;
		reset_test(1);

		@(negedge clk) wavedrom_start();
			@(posedge clk) x <= 0;
			@(posedge clk) x <= 0;
			@(posedge clk) x <= 0;
			@(posedge clk) x <= 1;
			@(posedge clk) x <= 0;
			@(posedge clk) x <= 1;
			@(posedge clk) x <= 0;
			@(posedge clk) x <= 1;
			@(posedge clk) x <= 1;
			@(posedge clk) x <= 0;
			@(posedge clk) x <= 1;
			@(posedge clk) x <= 0;
		@(negedge clk) wavedrom_stop();

		repeat(400) @(posedge clk, negedge clk) begin
			x <= $random;
			reset <= ($random&31) == 0;
		end

		$finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		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 aresetn;
	logic x;
	logic z_ref;
	logic z_dut;

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

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.aresetn,
		.x );
	reference_module good1 (
		.clk,
		.aresetn,
		.x,
		.z(z_ref) );

	top_module top_module1 (
		.clk,
		.aresetn,
		.x,
		.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_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 = ( { z_ref } === ( { z_ref } ^ { z_dut } ^ { 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 (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

detail_description:
	when the input x is 0, and the state is S, the state next is S.
	when the input x is 1, and the state is S, the state next is S1.
	when the input x is 0, and the state is S1, the state next is S10.
	when the input x is 1, and the state is S1, the state next is S1.
	when the input x is 0, and the state is S10, the state next is S.
	when the input x is 1, and the state is S10, the state next is S1.

	when the input state is S, the output z is 0.
	when the input state is S1, the output z is 0.
	when the input state is S10, the output z is the input x.


prompt:
module top_module (
	input clk,
	input reset,
	input w,
	output z
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input reset,
	input w,
	output z
);
	parameter A=0, B=1, C=2, D=3, E=4, F=5;
	reg [2:0] state, next;

	always @(posedge clk)
		if (reset)
			state <= A;
		else
			state <= next;

	always_comb begin
		case(state)
			A: next = w ? A : B;
			B: next = w ? D : C;
			C: next = w ? D : E;
			D: next = w ? A : F;
			E: next = w ? D : E;
			F: next = w ? D : C;
			default: next = 'x;
		endcase
	end

	assign z = (state == E || state == F);

endmodule

module stimulus_gen (
	input clk,
	output logic reset,
	output logic w
);

	initial begin
		repeat(200) @(posedge clk, negedge clk) begin
			w <= $random;
			reset <= ($random & 15) == 0;
		end

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		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 reset;
	logic w;
	logic z_ref;
	logic z_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,reset,w,z_ref,z_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.reset,
		.w );
	reference_module good1 (
		.clk,
		.reset,
		.w,
		.z(z_ref) );

	top_module top_module1 (
		.clk,
		.reset,
		.w,
		.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_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 = ( { z_ref } === ( { z_ref } ^ { z_dut } ^ { 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 (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

detail_description: This top Verilog module is a state machine that outputs a one-bit signal z. The module has four ports: a clock (clk), a reset (reset), an input (w), and an output (z). The module has six states, A to F. The next state of the state machine is determined by the current state and the input w. The transition from state A to state B is taken when the input w is low. The transition from state A to state A is taken when the input w is high. The transition from state B to state D is taken when the input w is high. The transition from state B to state C is taken when the input w is low. The transition from state C to state D is taken when the input w is high. The transition from state C to state E is taken when the input w is low. The transition from state D to state A is taken when the input w is high. The transition from state D to state F is taken when the input w is low. The transition from state E to state D is taken when the input w is high. The transition from state E to state E is taken when the input w is low. The transition from state F to state D is taken when the input w is high. The transition from state F to state C is taken when the input w is low.  The state machine is triggered by the clk signal. When the clk signal is high, the state machine will check the reset signal. If the reset signal is high, the state machine will reset to state A, otherwise the state machine will transition to the next state. The output z is high when the state machine is in state E or F, and is low otherwise.


prompt:
module top_module (
	input clk,
	input [7:0] in,
	input reset,
	output [23:0] out_bytes,
	output done
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input [7:0] in,
	input reset,
	output [23:0] out_bytes,
	output done
);
	parameter BYTE1=0, BYTE2=1, BYTE3=2, DONE=3;
	reg [1:0] state;
	reg [1:0] next;

    wire in3 = in[3];

    always_comb begin
		case (state)
			BYTE1: next = in3 ? BYTE2 : BYTE1;
			BYTE2: next = BYTE3;
			BYTE3: next = DONE;
			DONE: next = in3 ? BYTE2 : BYTE1;
		endcase
    end

    always @(posedge clk) begin
		if (reset) state <= BYTE1;
        else state <= next;
	end

	assign done = (state==DONE);

	reg [23:0] out_bytes_r;
	always @(posedge clk)
		out_bytes_r <= {out_bytes_r[15:0], in};

	// Implementations may vary: Allow user to do anything while the output doesn't have to be valid.
	assign out_bytes = done ? out_bytes_r : 'x;

endmodule

module stimulus_gen (
	input clk,
	output logic [7:0] in,
	output logic reset
);

	initial begin
		repeat(200) @(negedge clk) begin
			in <= $random;
			reset <= !($random & 31);
		end
		reset <= 1'b0;
		in <= '0;
		repeat(10) @(posedge clk);

		repeat(200) begin
			in <= $random;
			in[3] <= 1'b1;
			@(posedge clk);
			in <= $random;
			@(posedge clk);
			in <= $random;
			@(posedge clk);
		end

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_out_bytes;
		int errortime_out_bytes;
		int errors_done;
		int errortime_done;

		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 [7:0] in;
	logic reset;
	logic [23:0] out_bytes_ref;
	logic [23:0] out_bytes_dut;
	logic done_ref;
	logic done_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,in,reset,out_bytes_ref,out_bytes_dut,done_ref,done_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.in,
		.reset );
	reference_module good1 (
		.clk,
		.in,
		.reset,
		.out_bytes(out_bytes_ref),
		.done(done_ref) );

	top_module top_module1 (
		.clk,
		.in,
		.reset,
		.out_bytes(out_bytes_dut),
		.done(done_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_bytes) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_bytes", stats1.errors_out_bytes, stats1.errortime_out_bytes);
		else $display("Hint: Output '%s' has no mismatches.", "out_bytes");
		if (stats1.errors_done) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "done", stats1.errors_done, stats1.errortime_done);
		else $display("Hint: Output '%s' has no mismatches.", "done");

		$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_bytes_ref, done_ref } === ( { out_bytes_ref, done_ref } ^ { out_bytes_dut, done_dut } ^ { out_bytes_ref, done_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_bytes_ref !== ( out_bytes_ref ^ out_bytes_dut ^ out_bytes_ref ))
		begin if (stats1.errors_out_bytes == 0) stats1.errortime_out_bytes = $time;
			stats1.errors_out_bytes = stats1.errors_out_bytes+1'b1; end
		if (done_ref !== ( done_ref ^ done_dut ^ done_ref ))
		begin if (stats1.errors_done == 0) stats1.errortime_done = $time;
			stats1.errors_done = stats1.errors_done+1'b1; end

	end
endmodule

simple_description: This module is a state machine that reads 8-bit inputs and outputs 24-bit outputs when done.

detail_description: The top Verilog module is a state machine that takes in an 8-bit input, in, and a clock signal, clk, and outputs a 24-bit output, out_bytes, and a done signal. The state machine consists of four states: BYTE1, BYTE2, BYTE3, and DONE. The state machine transitions from BYTE1 to BYTE2 if the third bit of the input is 1, from BYTE2 to BYTE3, and from BYTE3 to DONE. If the third bit of the input is 0, the state machine transitions from BYTE1 to BYTE1 and from DONE to BYTE1. The done signal is set to 1 when the state machine is in the DONE state.  The out_bytes output is a 24-bit register that is updated on the rising edge of the clock signal. The 8-bit input is shifted into the register on each clock cycle, and the register is shifted left by 8 bits. The out_bytes output is set to the contents of the register when the done signal is set to 1.


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

test:
`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

simple_description: This module assigns Y1 to the bitwise AND of y[0] and w, and Y3 to the bitwise AND of the OR of y[1], y[2], y[4], and y[5], and the NOT of w.

detail_description: This Verilog module is a combinational logic circuit that takes in 6-bit input vector y and a single bit input w. The module then outputs two signals Y1 and Y3.   Y1 is the logical AND of the first bit of the input vector y and the single bit input w. Y3 is the logical AND of the logical OR of the second, third, fifth and sixth bits of the input vector y and the logical NOT of the single bit input w.   In other words, Y1 is true if both the first bit of the input vector y and the single bit input w are true, and Y3 is true if at least one of the second, third, fifth and sixth bits of the input vector y is true and the single bit input w is false.


prompt:
module top_module(
	input [2:0] vec,
	output [2:0] outv,
	output o2,
	output o1,
	output o0
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input [2:0] vec,
	output [2:0] outv,
	output o2,
	output o1,
	output o0
);

	assign outv = vec;
	assign {o2, o1, o0} = vec;

endmodule

module stimulus_gen (
	input clk,
	output reg [2:0] vec,
	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
		int count; count = 0;
		vec <= 3'b0;
		@(negedge clk);
		wavedrom_start();
		repeat(10) @(posedge clk)
			vec <= count++;
		wavedrom_stop();

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_outv;
		int errortime_outv;
		int errors_o2;
		int errortime_o2;
		int errors_o1;
		int errortime_o1;
		int errors_o0;
		int errortime_o0;

		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 [2:0] vec;
	logic [2:0] outv_ref;
	logic [2:0] outv_dut;
	logic o2_ref;
	logic o2_dut;
	logic o1_ref;
	logic o1_dut;
	logic o0_ref;
	logic o0_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,vec,outv_ref,outv_dut,o2_ref,o2_dut,o1_ref,o1_dut,o0_ref,o0_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.vec );
	reference_module good1 (
		.vec,
		.outv(outv_ref),
		.o2(o2_ref),
		.o1(o1_ref),
		.o0(o0_ref) );

	top_module top_module1 (
		.vec,
		.outv(outv_dut),
		.o2(o2_dut),
		.o1(o1_dut),
		.o0(o0_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_outv) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "outv", stats1.errors_outv, stats1.errortime_outv);
		else $display("Hint: Output '%s' has no mismatches.", "outv");
		if (stats1.errors_o2) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "o2", stats1.errors_o2, stats1.errortime_o2);
		else $display("Hint: Output '%s' has no mismatches.", "o2");
		if (stats1.errors_o1) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "o1", stats1.errors_o1, stats1.errortime_o1);
		else $display("Hint: Output '%s' has no mismatches.", "o1");
		if (stats1.errors_o0) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "o0", stats1.errors_o0, stats1.errortime_o0);
		else $display("Hint: Output '%s' has no mismatches.", "o0");

		$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 = ( { outv_ref, o2_ref, o1_ref, o0_ref } === ( { outv_ref, o2_ref, o1_ref, o0_ref } ^ { outv_dut, o2_dut, o1_dut, o0_dut } ^ { outv_ref, o2_ref, o1_ref, o0_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 (outv_ref !== ( outv_ref ^ outv_dut ^ outv_ref ))
		begin if (stats1.errors_outv == 0) stats1.errortime_outv = $time;
			stats1.errors_outv = stats1.errors_outv+1'b1; end
		if (o2_ref !== ( o2_ref ^ o2_dut ^ o2_ref ))
		begin if (stats1.errors_o2 == 0) stats1.errortime_o2 = $time;
			stats1.errors_o2 = stats1.errors_o2+1'b1; end
		if (o1_ref !== ( o1_ref ^ o1_dut ^ o1_ref ))
		begin if (stats1.errors_o1 == 0) stats1.errortime_o1 = $time;
			stats1.errors_o1 = stats1.errors_o1+1'b1; end
		if (o0_ref !== ( o0_ref ^ o0_dut ^ o0_ref ))
		begin if (stats1.errors_o0 == 0) stats1.errortime_o0 = $time;
			stats1.errors_o0 = stats1.errors_o0+1'b1; end

	end
endmodule

simple_description: This Verilog module assigns the input vector 'vec' to the output vector 'outv' and assigns each bit of 'vec' to the individual outputs 'o2', 'o1', and 'o0'.

detail_description: This top Verilog module is a simple 3-bit vector to 3-bit scalar converter. It has 3 inputs, vec, which is a 3-bit vector, and 5 outputs, outv, o2, o1, and o0. The outv output is a 3-bit vector that is the same as the input vector, vec. The o2, o1, and o0 outputs are 3 scalar outputs, each representing one bit of the input vector. The o2 output is the most significant bit of the input vector, vec, the o1 output is the middle bit, and the o0 output is the least significant bit. The module assigns the outv output to be the same as the vec input, and assigns the o2, o1, and o0 outputs to be the same as the bits of the vec input.


prompt:
module top_module (
	input a,
	input b,
	input c,
	input d,
	output reg out
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input a,
	input b,
	input c,
	input d,
	output reg out
);

    always @(*) begin
        case({a,b,c,d})
            4'h0: out = 0;
            4'h1: out = 1;
            4'h3: out = 0;
            4'h2: out = 1;
            4'h4: out = 1;
            4'h5: out = 0;
            4'h7: out = 1;
            4'h6: out = 0;
            4'hc: out = 0;
            4'hd: out = 1;
            4'hf: out = 0;
            4'he: out = 1;
            4'h8: out = 1;
            4'h9: out = 0;
            4'hb: out = 1;
            4'ha: out = 0;
        endcase
    end
endmodule

module stimulus_gen (
	input clk,
	output reg a, b, c, d,
	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
		int count; count = 0;
		{a,b,c,d} <= 4'b0;
		wavedrom_start();
		repeat(16) @(posedge clk)
			{a,b,c,d} <= count++;
		@(negedge clk) wavedrom_stop();

		repeat(200) @(posedge clk, negedge clk)
			{d,c,b,a} <= $urandom;

		#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 a;
	logic b;
	logic c;
	logic d;
	logic out_ref;
	logic out_dut;

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

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.a,
		.b,
		.c,
		.d );
	reference_module good1 (
		.a,
		.b,
		.c,
		.d,
		.out(out_ref) );

	top_module top_module1 (
		.a,
		.b,
		.c,
		.d,
		.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

simple_description: This module assigns a value to the output based on the values of the four inputs.

detail_description: This Verilog module is a combinational logic circuit that takes four binary inputs (a, b, c, and d) and produces one binary output (out). The output is determined by the combination of the four inputs. The module uses a case statement to determine the output based on the combination of the four inputs.   For example, if the inputs a, b, c, and d are all 0, then the output out is 0. If the inputs a, b, c, and d are all 1, then the output out is 1. Similarly, if the inputs a, b, c, and d are 0, 1, 0, and 1 respectively, then the output out is 0. The module will produce the same output for any combination of the four inputs.   The module is implemented using an always block with a case statement. The case statement is used to map the four input combinations to the corresponding output. The inputs are combined into a 4-bit vector and used as the case statement selector. The output is assigned to the corresponding case statement.   The module is used to implement a combinational logic circuit. It is used to produce a single output based on the combination of four binary inputs.


prompt:
module top_module (
	input [15:0] in,
	output [7:0] out_hi,
	output [7:0] out_lo
);

canonical_solution:
	assign {out_hi, out_lo} = in;

endmodule

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [15:0] in,
	output [7:0] out_hi,
	output [7:0] out_lo
);

	assign {out_hi, out_lo} = in;

endmodule

module stimulus_gen (
	input clk,
	output logic [15:0] 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

	always @(posedge clk, negedge clk)
		in <= $random;

	initial begin
		wavedrom_start("Random inputs");
		repeat(10) @(posedge clk);
		wavedrom_stop();
		repeat(100) @(negedge clk);
		$finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_out_hi;
		int errortime_out_hi;
		int errors_out_lo;
		int errortime_out_lo;

		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 [15:0] in;
	logic [7:0] out_hi_ref;
	logic [7:0] out_hi_dut;
	logic [7:0] out_lo_ref;
	logic [7:0] out_lo_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,in,out_hi_ref,out_hi_dut,out_lo_ref,out_lo_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.in );
	reference_module good1 (
		.in,
		.out_hi(out_hi_ref),
		.out_lo(out_lo_ref) );

	top_module top_module1 (
		.in,
		.out_hi(out_hi_dut),
		.out_lo(out_lo_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_hi) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_hi", stats1.errors_out_hi, stats1.errortime_out_hi);
		else $display("Hint: Output '%s' has no mismatches.", "out_hi");
		if (stats1.errors_out_lo) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_lo", stats1.errors_out_lo, stats1.errortime_out_lo);
		else $display("Hint: Output '%s' has no mismatches.", "out_lo");

		$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_hi_ref, out_lo_ref } === ( { out_hi_ref, out_lo_ref } ^ { out_hi_dut, out_lo_dut } ^ { out_hi_ref, out_lo_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_hi_ref !== ( out_hi_ref ^ out_hi_dut ^ out_hi_ref ))
		begin if (stats1.errors_out_hi == 0) stats1.errortime_out_hi = $time;
			stats1.errors_out_hi = stats1.errors_out_hi+1'b1; end
		if (out_lo_ref !== ( out_lo_ref ^ out_lo_dut ^ out_lo_ref ))
		begin if (stats1.errors_out_lo == 0) stats1.errortime_out_lo = $time;
			stats1.errors_out_lo = stats1.errors_out_lo+1'b1; end

	end
endmodule

simple_description: This Verilog module assigns the 16-bit input 'in' to two 8-bit outputs 'out_hi' and 'out_lo'.

detail_description: This Verilog module is a simple 16-bit to 8-bit splitter. It takes a 16-bit input signal, "in", and splits it into two 8-bit signals, "out_hi" and "out_lo". The two 8-bit signals are the upper and lower 8 bits of the original 16-bit signal, respectively. The module does not contain any logic, it simply assigns the two 8-bit signals to the 16-bit input signal. This module is useful when splitting a 16-bit signal into two 8-bit signals is necessary.


task_id: norgate

prompt:
module top_module(
	input a,
	input b,
	output out
);

canonical_solution:
	assign out = ~(a | b);

endmodule

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input a,
	input b,
	output out
);

	assign out = ~(a | b);

endmodule

module stimulus_gen (
	input clk,
	output reg a, b,
	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
		int count; count = 0;
		{a,b} <= 1'b0;
		wavedrom_start("NOR gate");
		repeat(10) @(posedge clk)
			{a,b} <= count++;
		wavedrom_stop();

		repeat(200) @(posedge clk, negedge clk)
			{b,a} <= $random;

		#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 a;
	logic b;
	logic out_ref;
	logic out_dut;

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

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

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

	top_module top_module1 (
		.a,
		.b,
		.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

simple_description: This module takes two inputs, a and b, and outputs the inverse of the logical OR of the two inputs.

detail_description: This top Verilog module takes two input signals, a and b, and produces an output signal, out. The output signal is the logical negation of the logical OR of the two inputs. This means that the output will be high when both inputs are low, and low when either of the inputs is high. This module is a simple logic gate, specifically an OR gate with an inverter. The OR gate takes the two inputs and produces a high output when either of the inputs is high, and the inverter inverts the output of the OR gate, producing a low output when either of the inputs is high.


prompt:
module top_module(
	input clk,
	input a,
	input b,
	output out_assign,
	output reg out_always_comb,
	output reg out_always_ff
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input clk,
	input a,
	input b,
	output out_assign,
	output reg out_always_comb,
	output reg out_always_ff
);

	assign out_assign = a ^ b;
	always @(*) out_always_comb = a ^ b;
	always @(posedge clk) out_always_ff <= a ^ b;

endmodule

module stimulus_gen (
	input clk,
	output reg a, b,
	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
		int count; count = 0;
		{a,b} <= 1'b0;
		wavedrom_start("XOR gate");
		repeat(10) @(posedge clk)
			{a,b} <= count++;
		wavedrom_stop();

		repeat(200) @(posedge clk, negedge clk)
			{b,a} <= $urandom;

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_out_assign;
		int errortime_out_assign;
		int errors_out_always_comb;
		int errortime_out_always_comb;
		int errors_out_always_ff;
		int errortime_out_always_ff;

		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 a;
	logic b;
	logic out_assign_ref;
	logic out_assign_dut;
	logic out_always_comb_ref;
	logic out_always_comb_dut;
	logic out_always_ff_ref;
	logic out_always_ff_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,a,b,out_assign_ref,out_assign_dut,out_always_comb_ref,out_always_comb_dut,out_always_ff_ref,out_always_ff_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.a,
		.b );
	reference_module good1 (
		.clk,
		.a,
		.b,
		.out_assign(out_assign_ref),
		.out_always_comb(out_always_comb_ref),
		.out_always_ff(out_always_ff_ref) );

	top_module top_module1 (
		.clk,
		.a,
		.b,
		.out_assign(out_assign_dut),
		.out_always_comb(out_always_comb_dut),
		.out_always_ff(out_always_ff_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_assign) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_assign", stats1.errors_out_assign, stats1.errortime_out_assign);
		else $display("Hint: Output '%s' has no mismatches.", "out_assign");
		if (stats1.errors_out_always_comb) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_always_comb", stats1.errors_out_always_comb, stats1.errortime_out_always_comb);
		else $display("Hint: Output '%s' has no mismatches.", "out_always_comb");
		if (stats1.errors_out_always_ff) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_always_ff", stats1.errors_out_always_ff, stats1.errortime_out_always_ff);
		else $display("Hint: Output '%s' has no mismatches.", "out_always_ff");

		$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_assign_ref, out_always_comb_ref, out_always_ff_ref } === ( { out_assign_ref, out_always_comb_ref, out_always_ff_ref } ^ { out_assign_dut, out_always_comb_dut, out_always_ff_dut } ^ { out_assign_ref, out_always_comb_ref, out_always_ff_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_assign_ref !== ( out_assign_ref ^ out_assign_dut ^ out_assign_ref ))
		begin if (stats1.errors_out_assign == 0) stats1.errortime_out_assign = $time;
			stats1.errors_out_assign = stats1.errors_out_assign+1'b1; end
		if (out_always_comb_ref !== ( out_always_comb_ref ^ out_always_comb_dut ^ out_always_comb_ref ))
		begin if (stats1.errors_out_always_comb == 0) stats1.errortime_out_always_comb = $time;
			stats1.errors_out_always_comb = stats1.errors_out_always_comb+1'b1; end
		if (out_always_ff_ref !== ( out_always_ff_ref ^ out_always_ff_dut ^ out_always_ff_ref ))
		begin if (stats1.errors_out_always_ff == 0) stats1.errortime_out_always_ff = $time;
			stats1.errors_out_always_ff = stats1.errors_out_always_ff+1'b1; end

	end
endmodule

simple_description: This module assigns the output of an XOR operation between inputs a and b to three different outputs, out_assign, out_always_comb, and out_always_ff.

detail_description: This Verilog module is a top-level module that has five ports: clk, a, b, out_assign, out_always_comb, and out_always_ff. The clk port is an input port that is used to synchronize the module's operations. The a and b ports are input ports that are used as input signals for the module. The out_assign, out_always_comb, and out_always_ff ports are output ports that are used to output the results of the module's operations.   The module performs a logical XOR operation on the a and b ports, and the result is assigned to the out_assign port. The out_always_comb port is assigned the same value as the out_assign port, but it is assigned using an always block, which is triggered whenever the values of the a and b ports change. The out_always_ff port is assigned the same value as the out_assign port, but it is assigned using an always block that is triggered on the rising edge of the clk port. This ensures that the out_always_ff port is updated synchronously with the clk port.


prompt:
module top_module (
	input [6:1] y,
	input w,
	output Y2,
	output Y4
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [6:1] y,
	input w,
	output Y2,
	output Y4
);
	assign Y2 = y[1]&~w;
	assign Y4 = (y[2]|y[3]|y[5]|y[6]) & w;

endmodule

module stimulus_gen (
	input clk,
	output logic[6:1] 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[6:5],temp[3:2]} == !{temp[4],temp[1]} );
			// Make y[4,1] and y[6,5,3,2] mutually exclusive, so we can accept Y4=(~y[1] & ~y[4]) &w as a valid answer too.

			y[6:1] <= temp[6:1];
			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_Y2;
		int errortime_Y2;
		int errors_Y4;
		int errortime_Y4;

		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 [6:1] y;
	logic w;
	logic Y2_ref;
	logic Y2_dut;
	logic Y4_ref;
	logic Y4_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,y,w,Y2_ref,Y2_dut,Y4_ref,Y4_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.y,
		.w );
	reference_module good1 (
		.y,
		.w,
		.Y2(Y2_ref),
		.Y4(Y4_ref) );

	top_module top_module1 (
		.y,
		.w,
		.Y2(Y2_dut),
		.Y4(Y4_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_Y2) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Y2", stats1.errors_Y2, stats1.errortime_Y2);
		else $display("Hint: Output '%s' has no mismatches.", "Y2");
		if (stats1.errors_Y4) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Y4", stats1.errors_Y4, stats1.errortime_Y4);
		else $display("Hint: Output '%s' has no mismatches.", "Y4");

		$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 = ( { Y2_ref, Y4_ref } === ( { Y2_ref, Y4_ref } ^ { Y2_dut, Y4_dut } ^ { Y2_ref, Y4_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 (Y2_ref !== ( Y2_ref ^ Y2_dut ^ Y2_ref ))
		begin if (stats1.errors_Y2 == 0) stats1.errortime_Y2 = $time;
			stats1.errors_Y2 = stats1.errors_Y2+1'b1; end
		if (Y4_ref !== ( Y4_ref ^ Y4_dut ^ Y4_ref ))
		begin if (stats1.errors_Y4 == 0) stats1.errortime_Y4 = $time;
			stats1.errors_Y4 = stats1.errors_Y4+1'b1; end

	end
endmodule

simple_description: This module assigns Y2 to the logical AND of the first bit of y and the logical NOT of w, and assigns Y4 to the logical AND of the logical OR of bits 2, 3, 5, and 6 of y and w.

detail_description: This module is used to generate two outputs, Y2 and Y4, based on the inputs y and w. Y2 is generated by taking the logical AND of the first bit of the input y and the logical NOT of the input w. Y4 is generated by taking the logical AND of the second, third, fifth and sixth bits of the input y and the input w.