小弟进来做个小程序 仿真过不了！
index 是个buffer端口 通过查表所得数值与其做加法运算 然后传给下一级使用，同时返回给输入端，由下一个输入再次更新~~
程序如下
--------------------------------------------------------------------
------------
-- Company:
-- Engineer:
--
-- Create Date: 22:48:39 05/04/07
-- Design Name:
-- Module Name: kuis_1 - Behavioral
-- Project Name:
-- Target Device:
-- Tool versions:
-- Description:
--
-- Dependencies:
--
-- Revision:
-- Revision 0.01 - File Created
-- Additional Comments:
--
--------------------------------------------------------------------
------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
---- Uncomment the following library declaration if instantiating
---- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;
entity kuis_1 is
Port ( code : in std_logic_vector(3 downto 0);
index : buffer std_logic_vector(8 downto 0));
end kuis_1;
architecture Behavioral of kuis_1 is
function adder9
( a:std_logic_vector;
b:std_logic_vector
)
return std_logic_vector is
variable vsum : std_logic_vector(8 downto 0);
variable carry : std_logic;
variable i:integer;
begin
carry :='0';
for i in 0 to 8 loop
vsum(i):= (a(i) xor b(i)) xor carry;
carry := (a(i) and b(i)) or (carry and (a(i) or b(i)));
end loop;
return vsum;
end adder9;
signal tmp:std_logic_vector(8 downto 0);
signal tmp1:std_logic_vector(8 downto 0);
begin
p1:process(code)
begin
case code is
when"0000"=> tmp<="111111111";
when"0001"=> tmp<="111111111";
when"0010"=> tmp<="111111111";
when"0011"=> tmp<="111111111";
when"0100"=> tmp<="000000010";
when"0101"=> tmp<="000000100";
when"0110"=> tmp<="000000110";
when"0111"=> tmp<="000001000";
when"1000"=> tmp<="111111111";
when"1001"=> tmp<="111111111";
when"1010"=> tmp<="111111111";
when"1011"=> tmp<="111111111";
when"1100"=> tmp<="000000010";
when"1101"=> tmp<="000000100";
when"1110"=> tmp<="000000110";
when"1111"=> tmp<="000001000";
when others=> tmp<="ZZZZZZZZZ";
end case;
end process p1;
p2:process(tmp,index)
begin
tmp1<=adder9(index,tmp);
index<=tmp1;
end process p2;
end Behavioral;
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