未定义的输出

Question

每次我模拟下面的代码时，我的输出都是未定义的，我不知道为什么。我在代码和模拟中都有数字库。如果有人能帮助让我知道。此外，在模拟输入成为00000..000而不是15和3

模块代码的输入：

library IEEE; 
use IEEE.STD_LOGIC_1164.ALL; 

USE ieee.numeric_std.ALL; 

entity EXPONENT_FUNCTION is 
    Port (A : in STD_LOGIC_VECTOR (23 downto 0); 
     B : in STD_LOGIC_VECTOR (23 downto 0); 
     O : out STD_LOGIC_VECTOR (47 downto 0)); 
end EXPONENT_FUNCTION; 

architecture Behavioral of EXPONENT_FUNCTION is 


signal AIN, BIN, F : integer; 
signal u : std_logic_vector (47 downto 0); 

begin 

AIN <= to_integer(signed (A)); 

BIN <= to_integer(signed (B)); 

F <= ((AIN)**(BIN)); 
u <= std_logic_vector(to_signed(F, 48)); 
O <= u; 


end Behavioral; 

模拟代码：

LIBRARY ieee; 
USE ieee.std_logic_1164.ALL; 
USE ieee.numeric_std.ALL; 

ENTITY EXPONENT_TEST IS 
END EXPONENT_TEST; 

ARCHITECTURE behavior OF EXPONENT_TEST IS 



    COMPONENT EXPONENT_FUNCTION 
    PORT(
     A : IN std_logic_vector(23 downto 0); 
     B : IN std_logic_vector(23 downto 0); 
     O : OUT std_logic_vector(47 downto 0) 
     ); 
    END COMPONENT; 



    signal A : std_logic_vector(23 downto 0) := (others => '0'); 
    signal B : std_logic_vector(23 downto 0) := (others => '0'); 


    signal O : std_logic_vector(47 downto 0); 

    BEGIN 

    uut: EXPONENT_FUNCTION PORT MAP (
      A => A, 
      B => B, 
      O => O 
     ); 


    stim_proc: process 
    begin   
    A <= "000000000000000000001111"; 
    B <= "000000000000000000000011"; 
     wait for 100 ns; 


     wait; 
    end process; 

END; 

Answer 1

为什么你有不确定的原因输出是你有运行时错误。这是因为指数运算符不能与负整数一起使用。如果更改类型natural和unsigned，它编译和运行：

architecture Behavioral of EXPONENT_FUNCTION is 

    signal AIN, BIN, F : natural; 
    signal u : std_logic_vector (47 downto 0); 

begin 

    AIN <= to_integer(unsigned (A)); 
    BIN <= to_integer(unsigned (B)); 

    F <= ((AIN)**(BIN)); 
    u <= std_logic_vector(to_unsigned(F, 48)); 
    O <= u; 

end Behavioral; 

https://www.edaplayground.com/x/6F3H