编码器VHDL代码

Question

-- Code your design here

library IEEE;

use IEEE.std_logic_1164.all;

entity encoder8_3 is

     port(

         din : in STD_LOGIC_VECTOR(7 downto 0);

         dout : out INTEGER RANGE 0 TO 15

         );

end encoder8_3;

architecture encoder8_3_arc of encoder8_3 is

begin

    dout <= "0" when (din="10000000") else
            "1" when (din="01000000") else
            "2" when (din="00100000") else
            "3" when (din="00010000") else
            "4" when (din="00001000") else
            "5" when (din="00000100") else
            "6" when (din="00000010") else
            "7";

end encoder8_3_arc;

这段代码会运行吗？我想返回整数来代替二进制等价。

Answer 1

为什么这段代码不会编译？

因为VHDL中的整数文字没有引号：

library IEEE;

use IEEE.std_logic_1164.all;

entity encoder8_3 is

     port(

         din : in STD_LOGIC_VECTOR(7 downto 0);

         dout : out INTEGER RANGE 0 TO 15

         );

end encoder8_3;

architecture encoder8_3_arc of encoder8_3 is

begin

    dout <= 0 when (din="10000000") else
            1 when (din="01000000") else
            2 when (din="00100000") else
            3 when (din="00010000") else
            4 when (din="00001000") else
            5 when (din="00000100") else
            6 when (din="00000010") else
            7;

end encoder8_3_arc;

http://www.edaplayground.com/x/5f2M

Answer 2

你必须删除整数值周围的引号：

dout <= 0 when (din="10000000") else
        1 when (din="01000000") else
        2 when (din="00100000") else
        3 when (din="00010000") else
        4 when (din="00001000") else
        5 when (din="00000100") else
        6 when (din="00000010") else
        7;

在这里运行一个简单的测试平台：http://www.edaplayground.com/x/5bwv我得到了以下输出：