1 files changed, 147 insertions, 0 deletions
diff --git a/verilog/decode.v b/verilog/decode.v
new file mode 100644
index 0000000..15108b6
--- /dev/null
+++ b/verilog/decode.v
@@ -0,0 +1,147 @@
+`default_nettype none
+`timescale 1ns/1ps
+
+module decode
+(
+	input wire [6:2] opcode,
+	input wire [2:0] func3,
+	input wire func7,
+
+	output reg wb_pc_d,
+	output reg wb_mem_d,
+
+	output reg wr_mem_d,
+	output reg wr_reg_d,
+
+	output reg [4:0] alu_op_d,
+	output reg alu_1_d,
+	output reg alu_2_d,
+
+	output reg branch_d,
+	output reg jump_d,
+	output reg jump_r_d,
+
+	output reg [3:0] i_b_j_u
+);
+
+always @ (*) begin
+	wb_pc_d  = 1'bx;
+	wb_mem_d = 1'bx;
+	wr_mem_d = 1'bx;
+	wr_reg_d = 1'bx;
+	alu_op_d = 5'bxxxxx;
+	alu_1_d  = 1'bx;
+	alu_2_d  = 1'bx;
+	branch_d = 1'bx;
+	jump_d   = 1'bx;
+	jump_r_d = 1'bx;
+	i_b_j_u  = 4'bxxxx;
+	case (opcode[6:2])
+		5'b01100: // R Type
+		begin
+			wb_mem_d = 1'b0;
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b1;
+			alu_op_d = {1'b0, func7, func3};
+			alu_1_d  = 1'b1;
+			alu_2_d  = 1'b1;
+			branch_d = 1'b0;
+			jump_d   = 1'b0;
+			i_b_j_u  = 4'bxxxx;
+		end
+		5'b00100: // Math I Type
+		begin
+			wb_mem_d = 1'b0;
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b1;
+			alu_op_d = {2'b0, func3};
+			alu_1_d = 1'b1;
+			alu_2_d = 1'b0;
+			branch_d = 1'b0;
+			jump_d = 1'b0;
+			i_b_j_u = 4'b1000;
+		end
+		5'b00000: // Load I Type
+		begin
+			wb_mem_d = 1'b1;
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b1;
+			alu_op_d = 5'b0;
+			alu_1_d  = 1'b1;
+			alu_2_d  = 1'b0;
+			branch_d = 1'b0;
+			jump_d   = 1'b0;
+			i_b_j_u  = 4'b1000;
+		end
+		5'b01000: // S Type
+		begin
+			wr_mem_d = 1'b1;
+			wr_reg_d = 1'b0;
+			alu_op_d = 5'b0;
+			alu_1_d  = 1'b1;
+			alu_2_d  = 1'b0;
+			branch_d = 1'b0;
+			jump_d   = 1'b0;
+			i_b_j_u  = 4'b0;
+		end
+		5'b11000: // B Type
+		begin
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b0;
+			alu_op_d = {2'b0, ~func3[2], func3[2], func3[1]};
+			alu_1_d  = 1'b1;
+			alu_2_d  = 1'b1;
+			branch_d = 1'b1;
+			jump_d   = 1'b0;
+			jump_r_d = 1'b0;
+			i_b_j_u  = 4'b0100;
+		end
+		5'b11011: // JAL
+		begin
+			wb_pc_d  = 1'b1;
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b1;
+			branch_d = 1'b0;
+			jump_d   = 1'b1;
+			jump_r_d = 1'b0;
+			i_b_j_u  =  4'b0010;
+		end
+		5'b11001: // JALR
+		begin
+			wb_pc_d  = 1'b1;
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b1;
+			branch_d = 1'b0;
+			jump_d   = 1'b1;
+			jump_r_d = 1'b1;
+			i_b_j_u  = 4'b0010;
+		end
+		5'b01101: // LUI
+		begin
+			wb_mem_d = 1'b0;
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b1;
+			alu_op_d = 5'b10000; // Pass through
+			alu_2_d  = 1'b0;
+			branch_d = 1'b0;
+			jump_d   = 1'b0;
+			i_b_j_u  = 4'b0001;
+		end
+		5'b00101: // AUIPC
+		begin
+			wb_mem_d = 1'b0;
+			wr_mem_d = 1'b0;
+			wr_reg_d = 1'b1;
+			alu_op_d = 5'b0; //ADD
+			alu_1_d  = 1'b0;
+			alu_2_d  = 1'b0;
+			branch_d = 1'b0;
+			jump_d   = 1'b0;
+			i_b_j_u  = 4'b0001;
+		end
+		default: begin
+		end
+	endcase
+end
+
+endmodule