标量与矢量的乘法

Question

我正在用VHDL编写代码，其中一个数字乘以一个矢量。但它给出了一个错误。

Library IEEE; 
use IEEE.std_logic_1164.all; 
use IEEE.numeric_std.all; 

entity multi is 
port ( clk : in std_logic; 
      ipixel : in std_logic_vector(15 downto 0); 
      opixel : out std_logic_vector(15 downto 0) 
    ); 

end entity multi; 

architecture rtl of multi is 
begin 

process (clk) begin 
    if rising_edge (clk) then 

     opixel (15 downto 11) <= std_logic_vector(unsigned(ipixel(15 downto 11))*3); 
     opixel (10 downto 5) <= std_logic_vector(unsigned(ipixel(10 downto 5))* 3); 
     opixel (4 downto 0) <= std_logic_vector(unsigned(ipixel(4 downto 0))* 3); 

    end if; 
end process; 
end architecture rtl; 

错误是：

目标切片5个元素;价值是10元

Answer 1

当你乘的无符号值与自然，这是在NUMERIC_STD定义如下：

function "*" (L: UNSIGNED; R: NATURAL) return UNSIGNED is 
begin 
    return L * TO_UNSIGNED(R, L'LENGTH); 
end "*"; 

返回值，将会导致您无符号的因素2 * length！