alu.v

多个Verilog和vhdl程序例子

// macro definitions for the opcodes
`define plus	3'd0
`define minus	3'd1
`define band	3'd2
`define bor		3'd3
`define unegate	3'd4

module alu(out, opcode, a, b);
output [7:0] out;
input [2:0] opcode;
input [7:0] a, b;

reg [7:0] out;

always @(opcode or a or b)
begin
	case (opcode)
		// arithmetic operations
		`plus:		out =	a + b;
		`minus:	out = 	a - b;
		// bitwise operations
		`band:	out = 	a & b;
		`bor:		out = 	a | b;
		// unary operations
		`unegate:	out = 	~a;
		default:	out = 	8'hx;
	endcase
end

endmodule