prompt:
module top_module (
	input [255:0] in,
	input [7:0] sel,
	output  out
);

canonical_solution:
	assign out = in[sel];

endmodule

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [255:0] in,
	input [7:0] sel,
	output  out
);

	assign out = in[sel];

endmodule

module stimulus_gen (
	input clk,
	output logic [255:0] in,
	output logic [7:0] sel
);

	always @(posedge clk, negedge clk) begin
		for (int i=0;i<8; i++)
			in[i*32+:32] <= $random;
		sel <= $random;
	end

	initial begin
		repeat(1000) @(negedge clk);
		$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 [255:0] in;
	logic [7:0] sel;
	logic out_ref;
	logic out_dut;

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

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

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

	top_module top_module1 (
		.in,
		.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 a specific bit of the input based on the selection value.

detail_description: This Verilog module is a top-level module that takes in an input vector of 256 bits (in) and an 8-bit selection vector (sel) and outputs a single bit (out). The output bit is determined by the selection vector, which is used to select one of the 256 bits from the input vector. The output bit is the bit from the input vector that corresponds to the selection vector. For example, if the selection vector is '10101010' (binary), the output bit will be the 8th bit of the input vector.


prompt:
module top_module (
	input clk,
	input w,
	input R,
	input E,
	input L,
	output reg Q
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input w,
	input R,
	input E,
	input L,
	output reg Q
);

	always @(posedge clk)
		if (L)
			Q <= R;
		else if (E)
			Q <= w;

endmodule

module stimulus_gen (
	input clk,
	output logic w, R, E, L
);

	initial begin
		repeat(200) @(posedge clk, negedge clk) begin
			{w,R,E,L} <= $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 w;
	logic R;
	logic E;
	logic L;
	logic Q_ref;
	logic Q_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,w,R,E,L,Q_ref,Q_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.w,
		.R,
		.E,
		.L );
	reference_module good1 (
		.clk,
		.w,
		.R,
		.E,
		.L,
		.Q(Q_ref) );

	top_module top_module1 (
		.clk,
		.w,
		.R,
		.E,
		.L,
		.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 simple register that stores the input "w" when "E" is high and the input "R" when "L" is high, and updates on the rising edge of the clock "clk".

detail_description: This top Verilog module is a simple register that is used to store a single bit of data. It has five inputs (clk, w, R, E, and L) and one output (Q). The clock input (clk) is used to trigger the register to update its output (Q) when the clock signal transitions from low to high. The other inputs are used to control the behavior of the register.  The input w is the data that is to be stored in the register. The input R is used to reset the register to a known state. When R is high, the output Q is forced to a low state. The input E is used to enable the register. When E is low, the output Q is held in its current state. The input L is used to control whether the data stored in the register is updated with the value of w or the value of R. When L is high, the output Q is updated with the value of R. When L is low, the output Q is updated with the value of w.  The module is implemented using an always block that is triggered on the rising edge of the clock signal. The always block contains a conditional statement that checks the value of the L input. If L is high, the output Q is updated with the value of R. If L is low, the output Q is updated with the value of w. If E is low, the output Q is held in its current state.


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

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

	reg [2:0] s = 0;

	always @(posedge clk) begin
		s <= { s[2] ^ x, ~s[1] & x, ~s[0] | x };
	end

	assign z = ~|s;

endmodule

module stimulus_gen (
	input clk,
	output logic x,
	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
		x <= 0;
		@(negedge clk) wavedrom_start();
			@(posedge clk) x <= 2'h0;
			@(posedge clk) x <= 2'h0;
			@(posedge clk) x <= 2'h0;
			@(posedge clk) x <= 2'h0;
			@(posedge clk) x <= 2'h1;
			@(posedge clk) x <= 2'h1;
			@(posedge clk) x <= 2'h1;
			@(posedge clk) x <= 2'h1;
		@(negedge clk) wavedrom_stop();
		repeat(100) @(posedge clk, negedge clk)
			x <= $random;

		$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 z_ref;
	logic z_dut;

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

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

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

	top_module top_module1 (
		.clk,
		.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:
The top module has the following inputs and outputs
Inputs: clk and x
Outputs: z

The following registers are defined
Register s is 3 bits and its inital value is 0

The following operations are performed
Always block
	Cascade notation is used to represent the state of s
	The first element is the MSB of s
	The second element is the middle bit of s
	The third element is the LSB of s
	The following statements are implemented in the always block
		Statement 1:
			The MSB of s is s[2]
			The value of x is exlusive ORed with the MSB of s
			The value of x is also assigned to the LSB of s
		Statement 2:
			The middle bit of s is s[1]
			The NOT operator is applied to the middle bit of s
			The value of x is ANDed with the output of the NOT operator
			The output of the AND operation is assigned to the middle bit of s
		Statement 3:
			The LSB of s is s[0]
			The NOT operator is applied to the LSB of s
			The value of x is ORed with the output of the NOT operator
			The output of the OR operation is assigned to the LSB of s

Assign output z
	The OR operator is applied to all bits of s
	The NOT operator is applied to the output of the OR operator
	The output of the NOT operator is assigned to output z


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

canonical_solution:
	assign q = c | b;

endmodule

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

	assign q = c | b;

endmodule

module stimulus_gen (
	input clk,
	output logic 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
		{a,b,c,d} <= 0;
		@(negedge clk) wavedrom_start("Unknown circuit");
			@(posedge clk) {a,b,c,d} <= 0;
			repeat(18) @(posedge clk, negedge clk) {a,b,c,d} <= {a,b,c,d} + 1;
		wavedrom_stop();

		repeat(100) @(posedge clk, negedge clk)
			{a,b,c,d} <= $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 b;
	logic c;
	logic d;
	logic q_ref;
	logic q_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,a,b,c,d,q_ref,q_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,
		.q(q_ref) );

	top_module top_module1 (
		.a,
		.b,
		.c,
		.d,
		.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 assigns the output q to the logical OR of inputs b and c.

detail_description: This top module is a simple logic gate that takes four inputs (a, b, c, and d) and produces one output (q). The output q is the result of a logical OR operation between the inputs b and c. This means that the output q will be high if either input b or input c is high, and it will be low if both inputs b and c are low. The inputs a and d are not used in this module.


prompt:
module top_module(
	input clk,
	input load,
	input [511:0] data,
	output reg [511:0] q);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input clk,
	input load,
	input [511:0] data,
	output reg [511:0] q);

	always @(posedge clk) begin
		if (load)
			q <= data;
		else begin
			q <=
			~((q[$bits(q)-1:1] & q[$bits(q)-1:0] & {q[$bits(q)-2:0], 1'b0}) |
			(~q[$bits(q)-1:1] & ~q[$bits(q)-1:0] & ~{q[$bits(q)-2:0], 1'b0}) |
			(q[$bits(q)-1:1] & ~q[$bits(q)-1:0] & ~{q[$bits(q)-2:0], 1'b0}) )
			;
		end
	end
endmodule

module stimulus_gen (
	input clk,
	output reg load,
	output reg[511:0] 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
		data <= 0;
		data[0] <= 1'b1;
		load <= 1;
		@(posedge clk); wavedrom_start("Load q[511:0] = 1: See Hint.");
		@(posedge clk);
		@(posedge clk);
		load <= 0;
		repeat(10) @(posedge clk);
		wavedrom_stop();

		data <= 0;
		data[256] <= 1'b1;
		load <= 1;
		@(posedge clk);
		@(posedge clk);
		@(posedge clk);
		load <= 0;
		repeat(1000) @(posedge clk) begin
		end
		data <= 512'h4df;
		load <= 1;
		@(posedge clk);
		load <= 0;
		repeat(1000) @(posedge clk) begin
		end
		data <= $random;
		load <= 1;
		@(posedge clk);
		load <= 0;
		repeat(1000) @(posedge clk) begin
		end

		data <= 0;
		load <= 1;
		repeat (20) @(posedge clk);
		@(posedge clk) data <= 2;
		@(posedge clk) data <= 4;
		@(posedge clk) begin
			data <= 9;
			load <= 0;
		end
		@(posedge clk) data <= 12;
		repeat(100) @(posedge clk);

		#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 [511:0] data;
	logic [511:0] q_ref;
	logic [511:0] q_dut;

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

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

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

	top_module top_module1 (
		.clk,
		.load,
		.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 is a register that uses the input "load" to determine whether to load the value in data into q.
If load is true, q is set to the value of data.
If load is false, q is set to the result of the bitwise operation:
Not(
(q[511:1] and q[511:0] and {q[510:0], 1'b0}) or
(not(q[511:1]) and not(q[511:0]) and not({q[510:0], 1'b0})) or
(q[511:1] and not(q[511:0]) and not({q[510:0], 1'b0})) )

The port connections of the instantiated modules are:
clk is connected to the clock input of q
load is connected to the load input of q
data is connected to the data input of q
q is connected to the output of q


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

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input clk,
	input in,
	input reset,
	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) begin
		if (reset) state <= A;
        else state <= next;
	end

	assign out = (state==D);

endmodule

module stimulus_gen (
	input clk,
	output logic in,
	output logic reset,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable,
	input tb_match
);
	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 reset;
	logic out_ref;
	logic out_dut;

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

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

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

	top_module top_module1 (
		.clk,
		.in,
		.reset,
		.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

detail_description:
This project is a FSM that has 4 states.
It has 3 inputs, clk, in and reset.
It has 1 output, out.
The 4 states are A, B, C, D and the initial state is A.
When the state is A, if the in is 1, the state changes to B,
otherwise the state remains to be A.
When the state is B, if the in is 1, the state changes to B,
otherwise the state changes to C.
When the state is C, if the in is 1, the state changes to D,
otherwise the state changes to A.
When the state is D, if the in is 1, the state changes to B,
otherwise the state changes to C.
When the reset is 1, the state changes to A.
The out is 1 when the state is D.


prompt:
module top_module (
	input [3:0] a,
	input [3:0] b,
	input [3:0] c,
	input [3:0] d,
	input [3:0] e,
	output reg [3:0] q
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [3:0] a,
	input [3:0] b,
	input [3:0] c,
	input [3:0] d,
	input [3:0] e,
	output reg [3:0] q
);

	always @(*)
		case (c)
			0: q = b;
			1: q = e;
			2: q = a;
			3: q = d;
			default: q = 4'hf;
		endcase

endmodule

module stimulus_gen (
	input clk,
	output logic [3:0] a,b,c,d,e,
	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
		@(negedge clk) wavedrom_start("Unknown circuit");
			@(posedge clk) {a,b,c,d,e} <= {20'hab0de};
			repeat(18) @(posedge clk, negedge clk) c <= c + 1;
		wavedrom_stop();

		@(negedge clk) wavedrom_start("Unknown circuit");
			@(posedge clk) {a,b,c,d,e} <= {20'h12034};
			repeat(8) @(posedge clk, negedge clk) c <= c + 1;
			@(posedge clk) {a,b,c,d,e} <= {20'h56078};
			repeat(8) @(posedge clk, negedge clk) c <= c + 1;
		wavedrom_stop();

		repeat(100) @(posedge clk, negedge clk)
			{a,b,c,d,e} <= $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 [3:0] a;
	logic [3:0] b;
	logic [3:0] c;
	logic [3:0] d;
	logic [3:0] e;
	logic [3:0] q_ref;
	logic [3:0] q_dut;

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

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.a,
		.b,
		.c,
		.d,
		.e );
	reference_module good1 (
		.a,
		.b,
		.c,
		.d,
		.e,
		.q(q_ref) );

	top_module top_module1 (
		.a,
		.b,
		.c,
		.d,
		.e,
		.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 takes in five 4-bit inputs and outputs a 4-bit value based on the value of the third input.

detail_description: This Verilog module is a top-level module that takes in five 4-bit inputs (a, b, c, d, and e) and produces one 4-bit output (q). The output q is a register, meaning that its value will be stored and can be used as an input in other modules.  The module uses an always block to continuously evaluate the value of the input c. Depending on the value of c, the output q will be assigned a different value. If c is 0, then q will be assigned the value of b. If c is 1, then q will be assigned the value of e. If c is 2, then q will be assigned the value of a. If c is 3, then q will be assigned the value of d. If c is any other value, then q will be assigned the value of 4'hf.


prompt:
module top_module (
	input sel,
	input [7:0] a,
	input [7:0] b,
	output reg [7:0] out
);

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

	// assign out = (~sel & a) | (sel & b);
    assign out = sel ? a : b;

endmodule

module stimulus_gen (
	input clk,
	output logic sel,
	output logic [7:0] 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
		{a, b, sel} <= '0;
		@(negedge clk) wavedrom_start("");
			@(posedge clk, negedge clk) {a,b,sel} <= {8'haa, 8'hbb, 1'b0};
			@(posedge clk, negedge clk) {a,b,sel} <= {8'haa, 8'hbb, 1'b0};
			@(posedge clk, negedge clk) {a,b,sel} <= {8'haa, 8'hbb, 1'b1};
			@(posedge clk, negedge clk) {a,b,sel} <= {8'haa, 8'hbb, 1'b0};
			@(posedge clk, negedge clk) {a,b,sel} <= {8'haa, 8'hbb, 1'b1};
			@(posedge clk, negedge clk) {a,b,sel} <= {8'haa, 8'hbb, 1'b1};

			@(posedge clk, negedge clk) {a, b} <= {8'hff, 8'h00}; sel <= 1'b0;
			@(posedge clk, negedge clk) sel <= 1'b0;
			@(posedge clk, negedge clk) sel <= 1'b1;
			@(posedge clk, negedge clk) sel <= 1'b0;
			@(posedge clk, negedge clk) sel <= 1'b1;
			@(posedge clk, negedge clk) sel <= 1'b1;
		wavedrom_stop();

		repeat(100) @(posedge clk, negedge clk)
			{a,b,sel} <= $urandom;
		$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 sel;
	logic [7:0] a;
	logic [7:0] b;
	logic [7:0] out_ref;
	logic [7:0] out_dut;

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

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

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

	top_module top_module1 (
		.sel,
		.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

detail_description:
The top Verilog module determines the value of output 'out' based on the value of input 'sel' and the data on 'a' and 'b'.
When 'sel' is 0, the value of 'out' is equal to the value of 'b'.
When 'sel' is 1, the value of 'out' is equal to the value of 'a'.

The port connections of instantiated modules:
sel --> sel
a   --> a
b   --> b
out <-- out


prompt:
module top_module(
	input clk,
	input L,
	input q_in,
	input r_in,
	output reg Q);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
/*
	Midterm 2015 Question 5a. Build a flip-flop with a 2-to-1 mux before it.
*/
module reference_module(
	input clk,
	input L,
	input q_in,
	input r_in,
	output reg Q);

	initial Q=0;
	always @(posedge clk)
		Q <= L ? r_in : q_in;

endmodule

module stimulus_gen (
	input clk,
	output logic L,
	output logic r_in,
	output logic q_in
);

	always @(posedge clk, negedge clk)
		{L, r_in, q_in} <= $random % 8;

	initial begin
		repeat(100) @(posedge clk);
		#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 L;
	logic q_in;
	logic r_in;
	logic Q_ref;
	logic Q_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,L,q_in,r_in,Q_ref,Q_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.L,
		.q_in,
		.r_in );
	reference_module good1 (
		.clk,
		.L,
		.q_in,
		.r_in,
		.Q(Q_ref) );

	top_module top_module1 (
		.clk,
		.L,
		.q_in,
		.r_in,
		.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 takes in two inputs (q_in and r_in) and an enable (L) and outputs the value of one of the inputs depending on the value of the enable.

detail_description: This Verilog module is a simple combinational logic circuit which implements a multiplexer. The module has five ports, four inputs and one output. The inputs are a clock signal (clk), a select signal (L), and two data inputs (q_in and r_in). The output is a single bit register (Q).  The module is triggered on the rising edge of the clock signal. When the clock signal is high, the logic circuit evaluates the select signal (L). If the select signal is high, the output register (Q) is set to the value of the second data input (r_in). If the select signal is low, the output register (Q) is set to the value of the first data input (q_in).  The initial value of the output register (Q) is set to 0. This ensures that the output register is in a known state before the first rising edge of the clock signal.  The module is useful for selecting between two data inputs based on a select signal. This allows for a single output to be driven by two different sources depending on the value of the select signal.


task_id: edgecapture

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

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

	reg [31:0] d_last;

	always @(posedge clk) begin
		d_last <= in;
		if (reset)
			out <= '0;
		else
			out <= out | (~in & d_last);
	end

endmodule

module stimulus_gen (
	input clk,
	input tb_match,
	output reg [31:0] in,
	output reg reset,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable
);

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

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

	task wavedrom_stop;
		#1;
	endtask

	initial begin
		in <= 0;
		reset <= 1;
		@(posedge clk);
		reset <= 1;
		in = 0;
		@(negedge clk) wavedrom_start("Example");
		repeat(1) @(posedge clk);
		reset = 0;
		@(posedge clk) in = 32'h2;
		repeat(4) @(posedge clk);
		in = 32'he;
		repeat(2) @(posedge clk);
		in = 0;
		@(posedge clk) in = 32'h2;
		repeat(2) @(posedge clk);
		reset = 1;
		@(posedge clk);
		reset = 0; in = 0;
		repeat(3) @(posedge clk);

		@(negedge clk) wavedrom_stop();

		@(negedge clk) wavedrom_start("");
		repeat(2) @(posedge clk);
		in <= 1;
		repeat(2) @(posedge clk);
		in <= 0;
		repeat(2) @(negedge clk);
		in <= 6;
		repeat(1) @(negedge clk);
		in <= 0;
		repeat(2) @(posedge clk);
		in <= 32'h10;
		repeat(2) @(posedge clk);
		reset <= 1;
		repeat(1) @(posedge clk);
		in <= 32'h0;
		repeat(1) @(posedge clk);
		reset <= 0;
		repeat(1) @(posedge clk);
		reset <= 1;
		in <= 32'h20;
		repeat(1) @(posedge clk);
		reset <= 0;
		in <= 32'h00;

		repeat(2) @(posedge clk);

		@(negedge clk) wavedrom_stop();

		repeat(200)
			@(posedge clk, negedge clk) begin
				in <= $random;
				reset <= !($random & 15);
			end
		$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 reset;
	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 ,clk,reset,in,out_ref,out_dut );
	end

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

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

	top_module top_module1 (
		.clk,
		.reset,
		.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

detail_description:
The signal clk is the clock signal and should be a signal that is asserted high for a very short time
and is then deasserted low. This signal is input to the module.
The signal reset is the signal that resets the state of the module and is input to the module.
The signal in is the input to the module and is a 32 bit signal.
The signal out is the output of the module and is a 32 bit signal.
The signal d_last is used to store the previous value of in.

When the clock signal is asserted the input value is stored in the d_last signal and the output value is
modified such that the value of out is assigned the value of out ORed with the NOT of the input
signal ANDed with the previous value of the input.

The output value of out is 0 initially when the reset is asserted.


prompt:
module top_module(
	input clk,
	input [7:0] d,
	output reg [7:0] q);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
	input clk,
	input [7:0] d,
	output reg [7:0] q);

	initial
		q = 8'h0;

	always @(posedge clk)
		q <= d;

endmodule

module stimulus_gen (
	input clk,
	output reg [7:0] 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

	always @(posedge clk, negedge clk)
		d <= $random % 256;

	initial begin
		@(posedge clk);
		wavedrom_start("Positive-edge triggered DFF");
		repeat(10) @(posedge clk);
		wavedrom_stop();
		#100;
		$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 [7:0] d;
	logic [7:0] q_ref;
	logic [7:0] q_dut;

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

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

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

	top_module top_module1 (
		.clk,
		.d,
		.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 assigns the value of the input 'd' to the output 'q' on the rising edge of the clock signal 'clk'.

detail_description: This top Verilog module is a simple 8-bit register with a clock input. It has three ports: a clock input, a data input, and a data output. The clock input is used to control when the data input is stored in the register. When the clock input goes from low to high, the data input is stored in the register and is output on the data output.   The module starts with an initial block which sets the output to a default value of 8'h0. This is the value that the register will output until the clock input is triggered.   The always block is triggered on the rising edge of the clock input. When this happens, the data input is stored in the register and is output on the data output. This allows the data input to be stored and output on the data output.   Overall, this module is a simple 8-bit register with a clock input. It takes in a data input and stores it in the register when the clock input is triggered. The stored data is then output on the data output.


prompt:
module top_module (
	input [7:0] a,
	input [7:0] b,
	output [7:0] s,
	output overflow
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [7:0] a,
	input [7:0] b,
	output [7:0] s,
	output overflow
);

	wire [8:0] sum = a+b;
	assign s = sum[7:0];
	assign overflow = !(a[7]^b[7]) && (a[7] != s[7]);

endmodule

module stimulus_gen (
	input clk,
	output logic [7:0] 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
		{a, b} <= 0;
		@(negedge clk) wavedrom_start();
			@(posedge clk) {a, b} <= 16'h0;
			@(posedge clk) {a, b} <= 16'h0070;
			@(posedge clk) {a, b} <= 16'h7070;
			@(posedge clk) {a, b} <= 16'h7090;
			@(posedge clk) {a, b} <= 16'h9070;
			@(posedge clk) {a, b} <= 16'h9090;
			@(posedge clk) {a, b} <= 16'h90ff;
		@(negedge clk) wavedrom_stop();
		repeat(100) @(posedge clk, negedge clk)
			{a,b} <= $random;

		$finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_s;
		int errortime_s;
		int errors_overflow;
		int errortime_overflow;

		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] a;
	logic [7:0] b;
	logic [7:0] s_ref;
	logic [7:0] s_dut;
	logic overflow_ref;
	logic overflow_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,a,b,s_ref,s_dut,overflow_ref,overflow_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.a,
		.b );
	reference_module good1 (
		.a,
		.b,
		.s(s_ref),
		.overflow(overflow_ref) );

	top_module top_module1 (
		.a,
		.b,
		.s(s_dut),
		.overflow(overflow_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_s) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "s", stats1.errors_s, stats1.errortime_s);
		else $display("Hint: Output '%s' has no mismatches.", "s");
		if (stats1.errors_overflow) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "overflow", stats1.errors_overflow, stats1.errortime_overflow);
		else $display("Hint: Output '%s' has no mismatches.", "overflow");

		$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 = ( { s_ref, overflow_ref } === ( { s_ref, overflow_ref } ^ { s_dut, overflow_dut } ^ { s_ref, overflow_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 (s_ref !== ( s_ref ^ s_dut ^ s_ref ))
		begin if (stats1.errors_s == 0) stats1.errortime_s = $time;
			stats1.errors_s = stats1.errors_s+1'b1; end
		if (overflow_ref !== ( overflow_ref ^ overflow_dut ^ overflow_ref ))
		begin if (stats1.errors_overflow == 0) stats1.errortime_overflow = $time;
			stats1.errors_overflow = stats1.errors_overflow+1'b1; end

	end
endmodule

simple_description: This module takes two 8-bit inputs, adds them together, and outputs the 8-bit sum and a single-bit overflow flag.

detail_description: This Verilog module is used to add two 8-bit numbers, a and b, and output the 8-bit sum, s, and an overflow bit. The module has four ports: two 8-bit inputs, a and b, an 8-bit output, s, and an overflow output.  The module first creates an 8-bit wire, sum, which is the sum of the two inputs, a and b. It then assigns the 8-bit output, s, to the 8 least significant bits of the sum. Finally, it assigns the overflow output to a logical expression which checks if the two inputs have the same sign and if the sign of the output is different from the sign of the inputs. If both of these conditions are true, then the overflow bit is set to 1, otherwise it is set to 0.


prompt:
module top_module(
    input d,
    input done_counting,
    input ack,
    input [9:0] state,    // 10-bit one-hot current state
    output B3_next,
    output S_next,
    output S1_next,
    output Count_next,
    output Wait_next,
    output done,
    output counting,
    output shift_ena
 );

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
    input d,
    input done_counting,
    input ack,
    input [9:0] state,    // 10-bit one-hot current state
    output B3_next,
    output S_next,
    output S1_next,
    output Count_next,
    output Wait_next,
    output done,
    output counting,
    output shift_ena
 );

	 parameter S=0, S1=1, S11=2, S110=3, B0=4, B1=5, B2=6, B3=7, Count=8, Wait=9;

	assign B3_next = state[B2];
	assign S_next = state[S]&~d | state[S1]&~d | state[S110]&~d | state[Wait]&ack;
	assign S1_next = state[S]&d;
	assign Count_next = state[B3] | state[Count]&~done_counting;
	assign Wait_next = state[Count]&done_counting | state[Wait]&~ack;

	assign done = state[Wait];
	assign counting = state[Count];
	assign shift_ena = |state[B3:B0];

endmodule

module stimulus_gen (
	input clk,
	output reg d, done_counting, ack,
	output reg [9:0] state,
	input tb_match
);
	bit failed = 0;
	bit fail_onehot = 0;

	always @(posedge clk, negedge clk)
		if (!tb_match)
			failed <= 1;

	initial begin
		{d, done_counting, ack} <= 3'h0;
		state <= 10'h0;

		repeat(300) @(posedge clk, negedge clk) begin
			{d, done_counting, ack} = $random;
			state <= 1<< ($unsigned($random) % 10);
		end

		@(posedge clk) fail_onehot <= failed;

		repeat(3000) @(posedge clk, negedge clk) begin
			{d, done_counting, ack} = $random;
			state <= $random;
		end

		@(posedge clk);
		if (!fail_onehot && failed) begin
			$display ("Hint: Your circuit passed when given only one-hot inputs, but not with random inputs.");
			$display ("Hint: Are you doing something more complicated than deriving state transition equations by inspection?\n");
		end

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_B3_next;
		int errortime_B3_next;
		int errors_S_next;
		int errortime_S_next;
		int errors_S1_next;
		int errortime_S1_next;
		int errors_Count_next;
		int errortime_Count_next;
		int errors_Wait_next;
		int errortime_Wait_next;
		int errors_done;
		int errortime_done;
		int errors_counting;
		int errortime_counting;
		int errors_shift_ena;
		int errortime_shift_ena;

		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 done_counting;
	logic ack;
	logic [9:0] state;
	logic B3_next_ref;
	logic B3_next_dut;
	logic S_next_ref;
	logic S_next_dut;
	logic S1_next_ref;
	logic S1_next_dut;
	logic Count_next_ref;
	logic Count_next_dut;
	logic Wait_next_ref;
	logic Wait_next_dut;
	logic done_ref;
	logic done_dut;
	logic counting_ref;
	logic counting_dut;
	logic shift_ena_ref;
	logic shift_ena_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,d,done_counting,ack,state,B3_next_ref,B3_next_dut,S_next_ref,S_next_dut,S1_next_ref,S1_next_dut,Count_next_ref,Count_next_dut,Wait_next_ref,Wait_next_dut,done_ref,done_dut,counting_ref,counting_dut,shift_ena_ref,shift_ena_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.d,
		.done_counting,
		.ack,
		.state );
	reference_module good1 (
		.d,
		.done_counting,
		.ack,
		.state,
		.B3_next(B3_next_ref),
		.S_next(S_next_ref),
		.S1_next(S1_next_ref),
		.Count_next(Count_next_ref),
		.Wait_next(Wait_next_ref),
		.done(done_ref),
		.counting(counting_ref),
		.shift_ena(shift_ena_ref) );

	top_module top_module1 (
		.d,
		.done_counting,
		.ack,
		.state,
		.B3_next(B3_next_dut),
		.S_next(S_next_dut),
		.S1_next(S1_next_dut),
		.Count_next(Count_next_dut),
		.Wait_next(Wait_next_dut),
		.done(done_dut),
		.counting(counting_dut),
		.shift_ena(shift_ena_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_B3_next) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "B3_next", stats1.errors_B3_next, stats1.errortime_B3_next);
		else $display("Hint: Output '%s' has no mismatches.", "B3_next");
		if (stats1.errors_S_next) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "S_next", stats1.errors_S_next, stats1.errortime_S_next);
		else $display("Hint: Output '%s' has no mismatches.", "S_next");
		if (stats1.errors_S1_next) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "S1_next", stats1.errors_S1_next, stats1.errortime_S1_next);
		else $display("Hint: Output '%s' has no mismatches.", "S1_next");
		if (stats1.errors_Count_next) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Count_next", stats1.errors_Count_next, stats1.errortime_Count_next);
		else $display("Hint: Output '%s' has no mismatches.", "Count_next");
		if (stats1.errors_Wait_next) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "Wait_next", stats1.errors_Wait_next, stats1.errortime_Wait_next);
		else $display("Hint: Output '%s' has no mismatches.", "Wait_next");
		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");
		if (stats1.errors_counting) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "counting", stats1.errors_counting, stats1.errortime_counting);
		else $display("Hint: Output '%s' has no mismatches.", "counting");
		if (stats1.errors_shift_ena) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "shift_ena", stats1.errors_shift_ena, stats1.errortime_shift_ena);
		else $display("Hint: Output '%s' has no mismatches.", "shift_ena");

		$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 = ( { B3_next_ref, S_next_ref, S1_next_ref, Count_next_ref, Wait_next_ref, done_ref, counting_ref, shift_ena_ref } === ( { B3_next_ref, S_next_ref, S1_next_ref, Count_next_ref, Wait_next_ref, done_ref, counting_ref, shift_ena_ref } ^ { B3_next_dut, S_next_dut, S1_next_dut, Count_next_dut, Wait_next_dut, done_dut, counting_dut, shift_ena_dut } ^ { B3_next_ref, S_next_ref, S1_next_ref, Count_next_ref, Wait_next_ref, done_ref, counting_ref, shift_ena_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 (B3_next_ref !== ( B3_next_ref ^ B3_next_dut ^ B3_next_ref ))
		begin if (stats1.errors_B3_next == 0) stats1.errortime_B3_next = $time;
			stats1.errors_B3_next = stats1.errors_B3_next+1'b1; end
		if (S_next_ref !== ( S_next_ref ^ S_next_dut ^ S_next_ref ))
		begin if (stats1.errors_S_next == 0) stats1.errortime_S_next = $time;
			stats1.errors_S_next = stats1.errors_S_next+1'b1; end
		if (S1_next_ref !== ( S1_next_ref ^ S1_next_dut ^ S1_next_ref ))
		begin if (stats1.errors_S1_next == 0) stats1.errortime_S1_next = $time;
			stats1.errors_S1_next = stats1.errors_S1_next+1'b1; end
		if (Count_next_ref !== ( Count_next_ref ^ Count_next_dut ^ Count_next_ref ))
		begin if (stats1.errors_Count_next == 0) stats1.errortime_Count_next = $time;
			stats1.errors_Count_next = stats1.errors_Count_next+1'b1; end
		if (Wait_next_ref !== ( Wait_next_ref ^ Wait_next_dut ^ Wait_next_ref ))
		begin if (stats1.errors_Wait_next == 0) stats1.errortime_Wait_next = $time;
			stats1.errors_Wait_next = stats1.errors_Wait_next+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
		if (counting_ref !== ( counting_ref ^ counting_dut ^ counting_ref ))
		begin if (stats1.errors_counting == 0) stats1.errortime_counting = $time;
			stats1.errors_counting = stats1.errors_counting+1'b1; end
		if (shift_ena_ref !== ( shift_ena_ref ^ shift_ena_dut ^ shift_ena_ref ))
		begin if (stats1.errors_shift_ena == 0) stats1.errortime_shift_ena = $time;
			stats1.errors_shift_ena = stats1.errors_shift_ena+1'b1; end

	end
endmodule

detail_description:
	The top module is a state machine. There are 10 states in this state machine, which are S, S1, S11, S110, B0, B1, B2, B3, Count and Wait.
	The done signal is 1 in the state Wait.
	The counting signal is 1 in the state Count.
	The shift_ena signal is 1 if any of the states B3, B2, B1 and B0 is active.
	The output of the top module B3_next is 1 when the state B2 is active.
	The output of the top module S_next is 1 when the state S and d is 0, or the state S1 and d is 0, or the state S110 and d is 0, or the state Wait and ack is 1.
	The output of the top module S1_next is 1 when the state S and d is 1.
	The output of the top module Count_next is 1 when the state B3 is active, or the state Count and done_counting is 0.
	The output of the top module Wait_next is 1 when the state Count and done_counting is 1, or the state Wait and ack is 0.


prompt:
module top_module(
    input clk,
    input areset,
    input train_valid,
    input train_taken,
    output logic [1:0] state
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module(
    input clk,
    input areset,
    input train_valid,
    input train_taken,
    output logic [1:0] state
);
    always @(posedge clk, posedge areset) begin
        if (areset)
            state <= 1;
        else if (train_valid) begin
            if(state < 3 && train_taken)
                state <= state + 1;
            else if(state > 0 && !train_taken)
                state <= state - 1;
        end
    end
endmodule

module stimulus_gen(
	input clk,
	output logic areset,
	output logic train_valid,
	output train_taken,

	input tb_match,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable,
	output int wavedrom_hide_after_time
);

// 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

	reg 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

	assign areset = reset;
	logic train_taken_r;
	assign train_taken = train_valid ? train_taken_r : 1'bx;

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

		wavedrom_start("Asynchronous reset");
			reset_test(1); // Test for asynchronous reset
		wavedrom_stop();
		@(posedge clk) reset <= 1;
		train_taken_r <= 1;
		train_valid <= 0;
		@(posedge clk) reset <= 0;

		wavedrom_start("Count up, then down");
		train_taken_r <= 1;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 0;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 0;
			@(posedge clk) train_valid <= 1;
		train_taken_r <= 0;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 0;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 1;
			@(posedge clk) train_valid <= 0;
			@(posedge clk) train_valid <= 1;
		wavedrom_stop();

		repeat(1000) @(posedge clk,negedge clk)
			{train_valid, train_taken_r} <= {$urandom} ;

		#1 $finish;
	end

endmodule
module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_state;
		int errortime_state;

		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 train_valid;
	logic train_taken;
	logic [1:0] state_ref;
	logic [1:0] state_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,areset,train_valid,train_taken,state_ref,state_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.areset,
		.train_valid,
		.train_taken );
	reference_module good1 (
		.clk,
		.areset,
		.train_valid,
		.train_taken,
		.state(state_ref) );

	top_module top_module1 (
		.clk,
		.areset,
		.train_valid,
		.train_taken,
		.state(state_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_state) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "state", stats1.errors_state, stats1.errortime_state);
		else $display("Hint: Output '%s' has no mismatches.", "state");

		$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 = ( { state_ref } === ( { state_ref } ^ { state_dut } ^ { state_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 (state_ref !== ( state_ref ^ state_dut ^ state_ref ))
		begin if (stats1.errors_state == 0) stats1.errortime_state = $time;
			stats1.errors_state = stats1.errors_state+1'b1; end

	end
endmodule

simple_description: This module implements a state machine which increments/decrements the state based on the values of train_valid and train_taken signals.

detail_description: This Verilog module is a state machine that transitions between states based on the values of two inputs. The inputs are a clock signal, "clk", an asynchronous reset signal, "areset", a valid signal, "train_valid", and a taken signal, "train_taken". The output is a two-bit signal, "state", which represents the current state of the machine.  The state machine transitions between four states, 0, 1, 2, and 3, which are represented by the two-bit output. When the asynchronous reset signal is asserted, the state machine is reset to state 1. When the valid signal is asserted, the state machine transitions between states based on the taken signal. If the taken signal is asserted and the current state is less than 3, the state machine transitions to the next state. If the taken signal is not asserted and the current state is greater than 0, the state machine transitions to the previous state. Otherwise, the state machine remains in its current state.


prompt:
module top_module (
	input [7:0] in,
	output reg [2:0] pos
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [7:0] in,
	output reg [2:0] pos
);

	always @(*) begin
		casez (in)
			default : pos = 2'h0;
			8'bzzzzzzz1: pos = 3'h0;
			8'bzzzzzz1z: pos = 3'h1;
			8'bzzzzz1zz: pos = 3'h2;
			8'bzzzz1zzz: pos = 3'h3;
			8'bzzz1zzzz: pos = 3'h4;
			8'bzz1zzzzz: pos = 3'h5;
			8'bz1zzzzzz: pos = 3'h6;
			8'b1zzzzzzz: pos = 3'h7;
		endcase
	end

endmodule

module stimulus_gen (
	input clk,
	output logic [7:0] 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
		@(negedge clk) wavedrom_start("Priority encoder");
			@(posedge clk) in <= 8'h1;
			repeat(8) @(posedge clk) in <= in << 1;
			in <= 8'h10;
			repeat(8) @(posedge clk) in <= in + 1;
		@(negedge clk) wavedrom_stop();

		repeat(50) @(posedge clk, negedge clk) begin
			in <= $urandom;
		end
		repeat(260) @(posedge clk, negedge clk) begin
			in <= in + 1;
		end
		$finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_pos;
		int errortime_pos;

		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 [2:0] pos_ref;
	logic [2:0] pos_dut;

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

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.in );
	reference_module good1 (
		.in,
		.pos(pos_ref) );

	top_module top_module1 (
		.in,
		.pos(pos_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_pos) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "pos", stats1.errors_pos, stats1.errortime_pos);
		else $display("Hint: Output '%s' has no mismatches.", "pos");

		$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 = ( { pos_ref } === ( { pos_ref } ^ { pos_dut } ^ { pos_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 (pos_ref !== ( pos_ref ^ pos_dut ^ pos_ref ))
		begin if (stats1.errors_pos == 0) stats1.errortime_pos = $time;
			stats1.errors_pos = stats1.errors_pos+1'b1; end

	end
endmodule

simple_description: This module assigns a 3-bit output based on the 8-bit input.

detail_description: This Verilog module is used to determine the position of a given 8-bit input. The module has two ports, an 8-bit input port "in" and a 3-bit output port "pos". The output port "pos" is a register, which means its value is stored until it is changed.  The module contains an always block, which is triggered whenever any of the inputs change. Inside the always block is a casez statement, which is used to compare the value of the 8-bit input "in" to a set of predefined values. Depending on the value of the input, the output port "pos" will be set to a different 3-bit value.  The default case is used to set the output port "pos" to the default value of 0. The other cases are used to set the output port "pos" to a different 3-bit value depending on the value of the 8-bit input "in". For example, if the 8-bit input "in" is equal to 8'bzzzzzzz1, then the output port "pos" will be set to 3'h0. Similarly, if the 8-bit input "in" is equal to 8'bz1zzzzzz, then the output port "pos" will be set to 3'h6.  Once the output port "pos" has been set, its value will remain until the 8-bit input "in" changes. This module can be used to determine the position of a given 8-bit input in a range of values.


prompt:
module top_module (
	input [15:0] scancode,
	output reg left,
	output reg down,
	output reg right,
	output reg up
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [15:0] scancode,
	output reg left,
	output reg down,
	output reg right,
	output reg up
);

	always @(*) begin
		{up, left, down, right} = 0;
		case (scancode)
			16'he06b: left = 1;
			16'he072: down = 1;
			16'he074: right = 1;
			16'he075: up = 1;
		endcase
	end

endmodule

module stimulus_gen (
	input clk,
	output logic [15:0] scancode,
	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
		@(negedge clk) wavedrom_start("Recognize arrow keys");
			@(posedge clk) scancode <= 16'h0;
			@(posedge clk) scancode <= 16'h1;
			@(posedge clk) scancode <= 16'he075;
			@(posedge clk) scancode <= 16'he06b;
			@(posedge clk) scancode <= 16'he06c;
			@(posedge clk) scancode <= 16'he072;
			@(posedge clk) scancode <= 16'he074;
			@(posedge clk) scancode <= 16'he076;
			@(posedge clk) scancode <= 16'hffff;
		@(negedge clk) wavedrom_stop();

		repeat(30000) @(posedge clk, negedge clk) begin
			scancode <= $urandom;
		end
		$finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_left;
		int errortime_left;
		int errors_down;
		int errortime_down;
		int errors_right;
		int errortime_right;
		int errors_up;
		int errortime_up;

		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] scancode;
	logic left_ref;
	logic left_dut;
	logic down_ref;
	logic down_dut;
	logic right_ref;
	logic right_dut;
	logic up_ref;
	logic up_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,scancode,left_ref,left_dut,down_ref,down_dut,right_ref,right_dut,up_ref,up_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.scancode );
	reference_module good1 (
		.scancode,
		.left(left_ref),
		.down(down_ref),
		.right(right_ref),
		.up(up_ref) );

	top_module top_module1 (
		.scancode,
		.left(left_dut),
		.down(down_dut),
		.right(right_dut),
		.up(up_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_left) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "left", stats1.errors_left, stats1.errortime_left);
		else $display("Hint: Output '%s' has no mismatches.", "left");
		if (stats1.errors_down) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "down", stats1.errors_down, stats1.errortime_down);
		else $display("Hint: Output '%s' has no mismatches.", "down");
		if (stats1.errors_right) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "right", stats1.errors_right, stats1.errortime_right);
		else $display("Hint: Output '%s' has no mismatches.", "right");
		if (stats1.errors_up) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "up", stats1.errors_up, stats1.errortime_up);
		else $display("Hint: Output '%s' has no mismatches.", "up");

		$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 = ( { left_ref, down_ref, right_ref, up_ref } === ( { left_ref, down_ref, right_ref, up_ref } ^ { left_dut, down_dut, right_dut, up_dut } ^ { left_ref, down_ref, right_ref, up_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 (left_ref !== ( left_ref ^ left_dut ^ left_ref ))
		begin if (stats1.errors_left == 0) stats1.errortime_left = $time;
			stats1.errors_left = stats1.errors_left+1'b1; end
		if (down_ref !== ( down_ref ^ down_dut ^ down_ref ))
		begin if (stats1.errors_down == 0) stats1.errortime_down = $time;
			stats1.errors_down = stats1.errors_down+1'b1; end
		if (right_ref !== ( right_ref ^ right_dut ^ right_ref ))
		begin if (stats1.errors_right == 0) stats1.errortime_right = $time;
			stats1.errors_right = stats1.errors_right+1'b1; end
		if (up_ref !== ( up_ref ^ up_dut ^ up_ref ))
		begin if (stats1.errors_up == 0) stats1.errortime_up = $time;
			stats1.errors_up = stats1.errors_up+1'b1; end

	end
endmodule

detail_description:
Scancode is the 16-bit scancode that is input from the keyboard through the USB cable.
UP, left, down, and right are the binary results of up, left, down, and right arrows pressed on the keyboard respectively.

If the 16-bit scancode is equal to 16'he06b, then the left is equal to 1, else the left is equal to 0.
If the 16-bit scancode is equal to 16'he072, then the down is equal to 1, else the down is equal to 0.
If the 16-bit scancode is equal to 16'he074, then the right is equal to 1, else the right is equal to 0.
If the 16-bit scancode is equal to 16'he075, then the up is equal to 1, else the up is equal to 0.

The 16-bit scancode is input to the module through the USB cable and then depending on the scancode value, the UP, left, down, and right are set to 1.


prompt:
module top_module (
	input [3:0] x,
	input [3:0] y,
	output [4:0] sum
);

canonical_solution:
	assign sum = x+y;
endmodule

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module (
	input [3:0] x,
	input [3:0] y,
	output [4:0] sum
);

	assign sum = x+y;
endmodule

module stimulus_gen (
	input clk,
	output logic [3:0] x,y
);

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

		#1 $finish;
	end

endmodule

module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_sum;
		int errortime_sum;

		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 [3:0] x;
	logic [3:0] y;
	logic [4:0] sum_ref;
	logic [4:0] sum_dut;

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

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.x,
		.y );
	reference_module good1 (
		.x,
		.y,
		.sum(sum_ref) );

	top_module top_module1 (
		.x,
		.y,
		.sum(sum_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_sum) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "sum", stats1.errors_sum, stats1.errortime_sum);
		else $display("Hint: Output '%s' has no mismatches.", "sum");

		$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 = ( { sum_ref } === ( { sum_ref } ^ { sum_dut } ^ { sum_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 (sum_ref !== ( sum_ref ^ sum_dut ^ sum_ref ))
		begin if (stats1.errors_sum == 0) stats1.errortime_sum = $time;
			stats1.errors_sum = stats1.errors_sum+1'b1; end

	end
endmodule

simple_description: This module takes two 4-bit inputs, x and y, and outputs the 5-bit sum of the two inputs.

detail_description: This Verilog module is a simple adder which takes two 4-bit inputs (x and y) and produces a 5-bit output (sum). The module contains no internal logic and simply assigns the sum of the two inputs to the output. The port connections of the module are as follows: x is the 4-bit input, y is the 4-bit input, and sum is the 5-bit output. The module is a combinational logic circuit, meaning that the output is determined solely by the current inputs and not by any previous state. The module will take the two 4-bit inputs (x and y) and add them together to produce a 5-bit output (sum). The output will be the sum of the two inputs, with the most significant bit being the carry bit.


prompt:
module top_module
(
    input clk,
    input areset,
    input predict_valid,
    input predict_taken,
    output logic [31:0] predict_history,

    input train_mispredicted,
    input train_taken,
    input [31:0] train_history
);

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
module reference_module
(
    input clk,
    input areset,
    input predict_valid,
    input predict_taken,
    output logic [31:0] predict_history,

    input train_mispredicted,
    input train_taken,
    input [31:0] train_history
);
    always@(posedge clk, posedge areset)
		if (areset) begin
			predict_history = 0;
        end	else begin
			if (train_mispredicted)
				predict_history <= {train_history, train_taken};
			else if (predict_valid)
				predict_history <= {predict_history, predict_taken};
		end
endmodule

module stimulus_gen
(
	input clk,
	output logic areset,

	output logic predict_valid,
	output predict_taken,

	output logic train_mispredicted,
	output train_taken,
	output [31:0] train_history,

	input tb_match,
	output reg[511:0] wavedrom_title,
	output reg wavedrom_enable,
	output int wavedrom_hide_after_time
);

// 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

	reg 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

	assign areset = reset;
	logic predict_taken_r;
	assign predict_taken = predict_valid ? predict_taken_r : 1'bx;

	logic train_taken_r;
	logic [31:0] train_history_r;
	assign train_taken = train_mispredicted ? train_taken_r : 1'bx;
	assign train_history = train_mispredicted ? train_history_r : 32'hx;

	initial begin
		@(posedge clk) reset <= 1;
		@(posedge clk) reset <= 0;
		predict_taken_r <= 1;
		predict_valid <= 1;
		train_mispredicted <= 0;
		train_history_r <= 32'h5;
		train_taken_r <= 1;

		wavedrom_start("Asynchronous reset");
			reset_test(1); // Test for asynchronous reset
		wavedrom_stop();
		@(posedge clk) reset <= 1;
		predict_valid <= 0;

		wavedrom_start("Predictions: Shift in");
		repeat(2) @(posedge clk) {predict_valid, predict_taken_r} <= {$urandom};
		reset <= 0;
		predict_valid <= 1;
		repeat(6) @(posedge clk) {predict_taken_r} <= {$urandom};
		predict_valid <= 0;
		repeat(3) @(posedge clk) {predict_taken_r} <= {$urandom};
		predict_valid <= 1;
		train_mispredicted <= 1;
		@(posedge clk) train_mispredicted <= 0;
		repeat(6) @(posedge clk) {predict_taken_r} <= {$urandom};
		wavedrom_stop();

		repeat(2000) @(posedge clk,negedge clk) begin
			{predict_valid, predict_taken_r, train_taken_r} <= {$urandom};
			train_history_r <= $urandom;
			train_mispredicted <= !($urandom_range(0,31));
		end

		#1 $finish;
	end

endmodule
module tb();

	typedef struct packed {
		int errors;
		int errortime;
		int errors_predict_history;
		int errortime_predict_history;

		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 predict_valid;
	logic predict_taken;
	logic train_mispredicted;
	logic train_taken;
	logic [31:0] train_history;
	logic [31:0] predict_history_ref;
	logic [31:0] predict_history_dut;

	initial begin
		$dumpfile("wave.vcd");
		$dumpvars(1, stim1.clk, tb_mismatch ,clk,areset,predict_valid,predict_taken,train_mispredicted,train_taken,train_history,predict_history_ref,predict_history_dut );
	end

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

	stimulus_gen stim1 (
		.clk,
		.* ,
		.areset,
		.predict_valid,
		.predict_taken,
		.train_mispredicted,
		.train_taken,
		.train_history );
	reference_module good1 (
		.clk,
		.areset,
		.predict_valid,
		.predict_taken,
		.train_mispredicted,
		.train_taken,
		.train_history,
		.predict_history(predict_history_ref) );

	top_module top_module1 (
		.clk,
		.areset,
		.predict_valid,
		.predict_taken,
		.train_mispredicted,
		.train_taken,
		.train_history,
		.predict_history(predict_history_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_predict_history) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "predict_history", stats1.errors_predict_history, stats1.errortime_predict_history);
		else $display("Hint: Output '%s' has no mismatches.", "predict_history");

		$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 = ( { predict_history_ref } === ( { predict_history_ref } ^ { predict_history_dut } ^ { predict_history_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 (predict_history_ref !== ( predict_history_ref ^ predict_history_dut ^ predict_history_ref ))
		begin if (stats1.errors_predict_history == 0) stats1.errortime_predict_history = $time;
			stats1.errors_predict_history = stats1.errors_predict_history+1'b1; end

	end
endmodule

simple_description: This module updates the predict_history based on the train_mispredicted, train_taken, and train_history signals, or the predict_taken signal if predict_valid is asserted.

detail_description: The top Verilog module is a branch predictor that predicts whether a branch instruction should be taken or not. It has an input clock (clk) and an asynchronous reset (areset) to control the module. It also has inputs for the prediction valid signal (predict_valid) and the prediction taken signal (predict_taken). The output of the module is the predict_history signal, which is a 32-bit vector that stores the history of the branch predictions.  The module also has inputs for the training signals, which are used to update the predict_history signal. The train_mispredicted signal indicates whether the previous prediction was mispredicted, while the train_taken signal indicates whether the branch was taken or not. The train_history signal is a 32-bit vector that stores the history of the actual branch instructions.  The module works by always checking the clock and reset signals. If the reset signal is asserted, the predict_history signal is reset to 0. If the reset signal is not asserted, the module checks the train_mispredicted and predict_valid signals. If the train_mispredicted signal is asserted, the predict_history signal is updated with the train_history and train_taken signals. If the predict_valid signal is asserted, the predict_history signal is updated with the predict_taken signal.


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

test:
`timescale 1 ps/1 ps
`define OK 12
`define INCORRECT 13
// hdlbits_prop {len: 5}
module reference_module (
	input a,
	input b,
	input c,
	input d,
	output out,
	output out_n );

	wire w1, w2;
	assign w1 = a&b;
	assign w2 = c&d;
	assign out = w1|w2;
	assign out_n = ~out;

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
		{a,b,c,d} = 4'h0;
		@(negedge clk);
		wavedrom_start("Exhaustive test");
		repeat(20) @(posedge clk, negedge clk)
			{d,c,b,a} <= {d,c,b,a} + 1'b1;
		wavedrom_stop();
		repeat(100) @(posedge clk, negedge clk) begin
			{a,b,c,d} <= $random;
		end

		#1 $finish;
	end

endmodule

module tb();

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

		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;
	logic out_n_ref;
	logic out_n_dut;

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

	top_module top_module1 (
		.a,
		.b,
		.c,
		.d,
		.out(out_dut),
		.out_n(out_n_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");
		if (stats1.errors_out_n) $display("Hint: Output '%s' has %0d mismatches. First mismatch occurred at time %0d.", "out_n", stats1.errors_out_n, stats1.errortime_out_n);
		else $display("Hint: Output '%s' has no mismatches.", "out_n");

		$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_n_ref } === ( { out_ref, out_n_ref } ^ { out_dut, out_n_dut } ^ { out_ref, out_n_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
		if (out_n_ref !== ( out_n_ref ^ out_n_dut ^ out_n_ref ))
		begin if (stats1.errors_out_n == 0) stats1.errortime_out_n = $time;
			stats1.errors_out_n = stats1.errors_out_n+1'b1; end

	end
endmodule

simple_description: This module takes four inputs (a, b, c, d) and produces two outputs (out and out_n) by performing a logical OR operation on the results of two logical AND operations.

detail_description: This top Verilog module is a combinational logic circuit that takes four inputs (a, b, c, and d) and produces two outputs (out and out_n). The module uses two wires (w1 and w2) to connect the inputs to the outputs. The first wire (w1) is assigned the value of the logical AND of inputs a and b. The second wire (w2) is assigned the value of the logical AND of inputs c and d. The output out is assigned the value of the logical OR of wires w1 and w2. The output out_n is assigned the logical NOT of the output out. This module is used to combine the inputs a, b, c, and d into a single output out and its complement out_n.


task_id: dff

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

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

	initial
		q = 1'hx;

	always @(posedge clk)
		q <= d;

endmodule

module stimulus_gen (
	input clk,
	output reg 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

	always @(posedge clk, negedge clk)
		d <= $urandom;

	initial begin
		@(posedge clk);
		wavedrom_start("Positive-edge triggered DFF");
		repeat(10) @(posedge clk);
		wavedrom_stop();

		repeat(100) @(posedge clk, negedge clk);
		$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 q_ref;
	logic q_dut;

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

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

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

	top_module top_module1 (
		.clk,
		.d,
		.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 assigns the value of the input 'd' to the output 'q' whenever the clock 'clk' is posedge.

detail_description: This Verilog module is a simple top-level module that takes in two inputs, a clock signal (clk) and a data signal (d), and outputs a register signal (q). The module has an initial block that sets the initial value of the register signal q to 1'hx, which is a hexadecimal representation of a one-bit value that is unknown or undefined.  The always block is triggered by the rising edge of the clock signal and sets the register signal q to the value of the data signal d. This module is used to synchronize the data signal d with the clock signal clk, so that the data signal is sampled at the rising edge of the clock signal.