AES_Decrypt.v.bak

module AES_Decrypt#(parameter N,parameter Nr,parameter Nk)(datain,key,state,reset,clk,start);
input [127:0] datain;
input [N-1:0] key;
output reg [127:0] state;
input reset;
input clk;
output reg start;

wire [(128*(Nr+1))-1:0] keys;
reg [127:0] a1;
wire [127:0] a2;
wire [127:0] a3;
reg [127:0] a4;
wire [127:0] b1;
wire [127:0] b2;
wire [127:0] b3;
	 
	 	 integer i = - Nr - 1;
				always @(posedge clk or posedge reset)begin
				if(reset) begin
						i = - Nr - 1;
						state=128'hx;
						a1 = 128'hx;
						a4 = 128'hx;
						start = 0;
				end
				else begin
				 case (i)
					0: begin a1 <= a3; state <= a3; start <= 1; end
					Nr-1: begin a4 <= a2; state <= a2; start <= 1; end
					Nr: begin state <= b3; start <= 1; end
					default: begin a1 <= a2; state <= a2; start <= 1; end
				 endcase
				if (i >= -Nr) begin
					i <= i + 1;
				end
				end
				end
	 
KeyExpansion #(N,Nr,Nk) ke (key, keys);
Addroundkey ark(datain, keys[127:0], a3);
 
invround ir(a1, a2, keys[128 * (i) +: 128]);

invShiftBytes ishb(a4,b1);
invsubBytes isb(b1,b2);
Addroundkey eark(b2,keys[128*Nr +: 128],b3);
endmodule