somador 2 bits

-- Somador 2 bits
-- Portas Entradas in_a0, in_a1, in_b0, in_b1 (tipo bit) / Saídas out_0, out_1, cout (tipo bit)
-- Autores: João Vitor e Marcos Meira

entity sum_2bits is
    port (in_a0, in_a1, in_b0, in_b1: in bit;
          out_0, out_1, cout: out bit);
end sum_2bits;

architecture dataflow of sum_2bits is
    signal sinal0, sinal1, sinal2, sinal3: bit;
begin
out_0 <= in_a0 xor in_b0;
sinal0 <= in_a0 and in_b0;
sinal1 <= in_a1 xor in_b1;
out_1 <= sinal0 xor sinal1;
sinal2 <= sinal0 and sinal1;
sinal3 <= in_a1 and in_b1;
cout <= sinal2 or sinal3;

end dataflow;