ULASomaSub.vhd

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;    -- Biblioteca IEEE para funções aritméticas

entity ULASomaSub is
    generic ( larguraDados : natural := 8 );
    port (
      entradaA, entradaB:  in STD_LOGIC_VECTOR((larguraDados-1) downto 0);
      seletor:  in STD_LOGIC_VECTOR(1 downto 0);
      saida:    out STD_LOGIC_VECTOR((larguraDados-1) downto 0)
    );
end entity;

architecture comportamento of ULASomaSub is
   signal soma :      STD_LOGIC_VECTOR((larguraDados-1) downto 0);
   signal subtracao : STD_LOGIC_VECTOR((larguraDados-1) downto 0);
   signal passa:      STD_LOGIC_VECTOR((larguraDados-1) downto 0);
	 begin
      soma      <= STD_LOGIC_VECTOR(unsigned(entradaA) + unsigned(entradaB));
      subtracao <= STD_LOGIC_VECTOR(unsigned(entradaA) - unsigned(entradaB));
      passa     <= STD_LOGIC_VECTOR(unsigned(entradaB));
		saida <= soma when (seletor = "01") else
					subtracao when(seletor = "00") else
					passa when (seletor = "10");
end architecture;