/
neg_datapath_tb.v
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neg_datapath_tb.v
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// neg datapath_tb.v file
`timescale 1ns/10ps
module neg_datapath_tb;
reg pc_out, z_low_out, mdr_out, r2_out, r4_out; // add any other signals to see in your simulation
reg mar_in, z_in, pc_in, mdr_in, ir_in, y_in;
reg inc_pc, read, r5_in, r2_in, r4_in;
reg clk, reset_n;
reg [31:0] m_data_in;
reg [3:0] alu_op;
parameter And = 4'b0000, Or = 4'b0001, Add = 4'b0010, Sub = 4'b0011, Shr = 4'b0100, Shl = 4'b0101,
Ror = 4'b0110, Rol = 4'b0111, Mul = 4'b1000, Div = 4'b1001, Neg = 4'b1010, Not = 4'b1011;
parameter Default = 4'b0000, Reg_load1a = 4'b0001, Reg_load1b = 4'b0010, Reg_load2a = 4'b0011,
Reg_load2b = 4'b0100, Reg_load3a = 4'b0101, Reg_load3b = 4'b0110, T0 = 4'b0111,
T1 = 4'b1000, T2 = 4'b1001, T3 = 4'b1010, T4 = 4'b1011;
reg [3:0] Present_state = Default;
wire [15:0] gpr_in;
wire [15:0] gpr_out;
assign gpr_in = {1'b0, 1'b0, 1'b0, 1'b0, 1'b0, 1'b0, 1'b0, 1'b0,
1'b0, 1'b0, r5_in, r4_in, 1'b0, r2_in, 1'b0, 1'b0};
assign gpr_out = {1'b0, 1'b0, 1'b0, 1'b0, 1'b0, 1'b0, 1'b0, 1'b0,
1'b0, 1'b0, 1'b0, r4_out, 1'b0, r2_out, 1'b0, 1'b0};
wire [31:0] bus_data;
datapath the_datapath(
.clk(clk),
.reset_n(reset_n),
.gpr_in(gpr_in),
.gpr_out(gpr_out),
.hi_in(1'b0),
.hi_out(1'b0),
.lo_in(1'b0),
.lo_out(1'b0),
.pc_in(pc_in),
.pc_out(pc_out),
.ir_in(ir_in),
.z_in(z_in),
.z_high_out(1'b0),
.z_low_out(z_low_out),
.inport_out(1'b0),
.c_out(1'b0),
.y_in(y_in),
.mar_in(mar_in),
.mdr_in(mdr_in),
.mdr_out(mdr_out),
.read(read),
.m_data_in(m_data_in),
.alu_op(alu_op),
.inc_pc(inc_pc),
.bus_data(bus_data));
initial
begin
clk = 0;
forever #10 clk = ~clk;
end
always @(posedge clk) // finite state machine; if clock rising-edge
begin
case (Present_state)
Default: #40 Present_state = Reg_load1a;
Reg_load1a: #40 Present_state = Reg_load1b;
Reg_load1b: #40 Present_state = Reg_load2a;
Reg_load2a: #40 Present_state = Reg_load2b;
Reg_load2b: #40 Present_state = Reg_load3a;
Reg_load3a: #40 Present_state = Reg_load3b;
Reg_load3b: #40 Present_state = T0;
T0: #40 Present_state = T1;
T1: #40 Present_state = T2;
T2: #40 Present_state = T3;
T3: #40 Present_state = T4;
endcase
end
always @(Present_state) // do the required job in each state
begin
case (Present_state) // assert the required signals in each clock cycle
Default: begin
pc_out <= 0;
z_low_out <= 0;
mdr_out <= 0;
r2_out <= 0;
r4_out <= 0;
mar_in <= 0;
z_in <= 0;
pc_in <=0;
mdr_in <= 0;
ir_in <= 0;
y_in <= 0;
inc_pc <= 0;
read <= 0;
r5_in <= 0;
r2_in <= 0;
r4_in <= 0;
m_data_in <= 32'h00000000;
alu_op <= 4'b0000;
reset_n <= 0;
#10 reset_n <= 1;
end
Reg_load1a: begin
m_data_in <= 32'h00000022;
read = 0;
mdr_in = 0; // the first zero is there for completeness
#10 read <= 1; mdr_in <= 1;
#15 read <= 0; mdr_in <= 0;
end
Reg_load1b: begin
#10 mdr_out <= 1; r2_in <= 1;
#15 mdr_out <= 0; r2_in <= 0; // initialize R2 with the value $22
end
Reg_load2a: begin
m_data_in <= 32'h00000024;
#10 read <= 1; mdr_in <= 1;
#15 read <= 0; mdr_in <= 0;
end
Reg_load2b: begin
#10 mdr_out <= 1; r4_in <= 1;
#15 mdr_out <= 0; r4_in <= 0; // initialize R4 with the value $24
end
Reg_load3a: begin
m_data_in <= 32'h000000FF;
#10 read <= 1; mdr_in <= 1;
#15 read <= 0; mdr_in <= 0;
end
Reg_load3b: begin
#10 mdr_out <= 1; r5_in <= 1;
#15 mdr_out <= 0; r5_in <= 0; // initialize R5 with the value $FF
end
T0: begin
#10 pc_out <= 1; mar_in <= 1; inc_pc <= 1; z_in <= 1; alu_op <= Add;
#15 pc_out <= 0; mar_in <= 0; inc_pc <= 0; z_in <= 0;
end
T1: begin
#10 z_low_out <= 1; pc_in <= 1; read <= 1; mdr_in <= 1; m_data_in <= 32'h82900000; // opcode for neg R5, R2
#15 z_low_out <= 0; pc_in <= 0; read <= 0; mdr_in <= 0;
end
T2: begin
#10 mdr_out <= 1; ir_in <= 1;
#15 mdr_out <= 0; ir_in <= 0;
end
T3: begin
#10 r2_out <= 1; alu_op <= Neg; z_in <= 1;
#15 r2_out <= 0; z_in <= 0;
end
T4: begin
#10 z_low_out <= 1; r5_in <= 1;
#15 z_low_out <= 0; r5_in <= 0;
end
endcase
end
endmodule