P_ID_Pipeline.v

module IF2ID(clk, next_PC_address, opcode, A_Reg, B_Reg, W_Reg, Sign, freeze, flush, 
 next_PC_address_O, opcode_O, A_Reg_O, B_Reg_O, W_Reg_O, Sign_O);

input clk;
input [7:0] next_PC_address;
input [3:0] opcode;
input [3:0] A_Reg;
input [3:0] B_Reg;
input [3:0] W_Reg;
input [3:0] Sign;
input freeze, flush;

output reg  [7:0] next_PC_address_O;
output reg  [3:0] opcode_O;
output reg  [3:0] A_Reg_O;
output reg  [3:0] B_Reg_O;
output reg  [3:0] W_Reg_O;
output reg  [3:0] Sign_O;

always @(negedge clk)begin
	if(~freeze)begin
		if(flush)begin
			next_PC_address_O <= 7'bx;
			opcode_O <= 3'bx;
			A_Reg_O <= 3'bx;
			B_Reg_O <= 3'bx;
			W_Reg_O <= 3'bx;
			Sign_O <= 3'bx;
		end
		else begin
			next_PC_address_O <= next_PC_address;
			opcode_O <= opcode;
			A_Reg_O <= A_Reg;
			B_Reg_O <= B_Reg;
			W_Reg_O <= W_Reg;
			Sign_O <= Sign;
		end
	end
end

endmodule

P_ID_Stage.v

module IF_ID(clk, reset, select_line, new_address, pc_select,
 opcode, A_reg_address, B_reg_address, W_reg_address, Sign, pc_to_im, next_pc_address);

input clk, reset;
input select_line;
input [7:0]new_address;
input pc_select;

output [3:0]opcode;
output [3:0]A_reg_address;
output [3:0]B_reg_address;
output [3:0]W_reg_address;
output [3:0]Sign;
output [7:0]pc_to_im;
output [7:0]next_pc_address;


wire [7:0] pc_out;
wire [7:0] pc_in, pc_to_im, next_pc_address;


//PC_ADD adder(pc_to_im,next_pc);
assign next_pc_address = pc_to_im + 2;
MUX8 mux4(next_pc_address, new_address, select_line, pc_in); 
//module PC(in,clk,pc_select,out);
PC P_Counter(pc_in, clk, pc_select, reset, pc_to_im);
//module IF_Stage(in,out,clk,pc_select,opcode,A_reg,B_reg,W_reg,Sign);
IM Instruction_Mem(pc_to_im, clk, reset, opcode, A_reg_address, B_reg_address, W_reg_address, Sign);


endmodule

P_Instruction_Memory.v

module IM(in,clk, reset, opcode, A_reg, B_reg, W_reg, Sign);
input [7:0]in;
input clk, reset;
reg [3:0]dest;
output [3:0]opcode;
output [3:0]A_reg;
output [3:0]B_reg;
output [3:0]W_reg;
output [3:0]Sign;

reg [7:0] imem[0:19];
reg [15:0] instruction; 
reg [8:0]temp;

always @(*)begin

if(reset) begin
imem[0]=8'b0001_0001; //0000
imem[1]=8'b0010_0001;

imem[2]=8'b0010_0101; //0010
imem[3]=8'b0101_0010; 

imem[4]=8'b0011_0111; //0100
imem[5]=8'b0111_0100;

imem[6]=8'b0100_0110; //0110
imem[7]=8'b0101_0110;

imem[8]=8'b0101_1010; //1000
imem[9]=8'b0111_0101;

imem[10]=8'b0110_0001; //1010
imem[11]=8'b0100_0110;

imem[12]=8'b1110_0010; //1100
imem[13]=8'b0011_0111;

imem[14]=8'b1111_0001; //1110
imem[15]=8'b0100_0010;

//imem[16]=8'b0001_0001; //1100
//imem[17]=8'b0100_1011; 


end

end

assign A_reg = imem[in][3:0];
assign opcode = imem[in][7:4];
assign B_reg = imem[in+1][7:4];
assign W_reg = imem[in+1][3:0];
assign Sign = imem[in+1][3:0];


endmodule

P_Mux4.v

module MUX8(a,b,sel,e);
input [7:0] a;
input [7:0] b;
input sel;
output reg [7:0]e;
always @(*)begin
if(sel)
	e = b;
else
	e = a;
end
endmodule

P_PC_Counter.v

module PC(in,clk,pc_select,reset,out);
input [7:0]in;
input pc_select, clk,reset;
output reg[7:0]out;
//output [7:0]next_out;
initial begin
//out = 8'b11111110;
end
reg [8:0]temp;

always @(negedge clk)begin
	if(reset)
		out <= 0;
	else if(pc_select)begin
		out <= in;
	end
end


endmodule