Paso de iteración CORDIC

Implementa un paso CORDIC usando aritmética signed de 8 bits.

• Si dir = '1' (CCW): x' = x − y, y' = y + x
• Si dir = '0' (CW): x' = x + y, y' = y − x

Convierte las entradas con signed(...) y el resultado con std_logic_vector(...).

x_out <= std_logic_vector(signed(x_in) - signed(y_in)) when dir = '1'
    else std_logic_vector(signed(x_in) + signed(y_in));
y_out <= std_logic_vector(signed(y_in) + signed(x_in)) when dir = '1'
    else std_logic_vector(signed(y_in) - signed(x_in));