原创 VHDL常见语句

type color is (blue,green,yellow,red);

signal p:color;------信号p是color数据类型

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type nn is array (1 downto 0) of std_logic_vector(2 downto 0);
signal n1,n2:nn;-------定义二维数组

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条件信号赋值语句：并行描述语句

x<='0' when a='0' and b='0' else

       '0'    when a='1' else

        '1'   ;

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选择信号赋值语句

with sel select

q<=d0 when"00",

      d1 when"01",

         d2 when others;