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谁能判断这是否是 MIPS 上逻辑左移 (sll) 和逻辑右移 (srl) 的正确代码？

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 ALU is
  port (RdData1 : in  std_logic_vector (31 downto 0);
        RdData2 : in  std_logic_vector (31 downto 0);
        FAddr   : in  std_logic_vector (15 downto 0);
        ALUSrc  : in  std_logic;
        ALUOP   : in  std_logic_vector (2 downto 0);  --S-a marit lungimea lui ALUOP
        Y       : out std_logic_vector (31 downto 0));
end ALU;

architecture Behavioral of ALU is

  signal SEAddr : std_logic_vector(31 downto 0);
  signal OP2    : std_logic_vector(31 downto 0);

begin

  SEAddr(15 downto 0)  <= FAddr(15 downto 0);
  SEAddr(31 downto 16) <= x"0000" when FAddr(15) = '0' else x"FFFF";

  OP2 <= RdData2 when ALUSrc = '0' else SEAddr;

  with ALUOP select
    Y <= RdData1 + OP2 when "000",               --S-a marit lungimea lui ALUOP
         RdData1 - OP2              when "001",  --S-a marit lungimea lui ALUOP
         RdData1 and OP2            when "010",  --S-a marit lungimea lui ALUOP
         RdData1 or OP2             when "011",  --S-a marit lungimea lui ALUOP
         RdData1(30 downto 0) & "0" when "100",  --sll ,
         "0" & RdData1(1 downto 31) when "101",  --srl ,
         RdData1                    when others;

end Behavioral;

我正在添加控制器，也许我的错误在这里，我将添加一个带有我的测试波的打印屏幕，以便您更好地理解为什么这不起作用：

entity ctrl is
Port ( OP : in  STD_LOGIC_VECTOR (5 downto 0);
       Funct : in  STD_LOGIC_VECTOR (5 downto 0);
       ALUSrc : out  STD_LOGIC;
       ALUOP : out  STD_LOGIC_VECTOR (2 downto 0);--S-a marit lungimea lui ALUOP 
       MemWr : out  STD_LOGIC;
       Mem2Reg : out  STD_LOGIC;
       RegWr : out  STD_LOGIC;
       RegDest : out  STD_LOGIC);
end ctrl;

architecture Behavioral of ctrl is
signal OPCIntrn :   std_logic_vector(6 downto 0);
signal temp         :   std_logic_vector(7 downto 0); 

begin
with OP select
OPCIntrn (6) <= '0' when "000000",
    '1' when others;

with OP select
OPCIntrn (5 downto 0) <= Funct when "000000",
OP when others;

with OPCIntrn select
temp <=         b"0_000_0_0_1_1" when b"010_0000",  --add
        b"0_001_0_0_1_1" when b"010_0010",   --sub
        b"0_010_0_0_1_1" when b"010_0100",   --and
        b"0_011_0_0_1_1" when b"010_0101",   --or
        b"1_000_0_1_1_0" when b"110_0011",   --lw
        b"0_100_0_0_1_1" when b"000_0000",   --sll
        b"0_101_0_0_1_1" when b"000_0010",   --sll
        b"1_000_1_0_0_0" when b"110_1011",   --sw
        b"0_000_0_0_0_0" when others;


RegDest <= temp(0);
RegWr <= temp(1);
Mem2Reg <= temp(2);
MemWr <= temp(3);
ALUOP (2 downto 0) <= temp(6 downto 4);  
ALUSrc <= temp(7);


end Behavioral;
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1 回答 1

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在上面的代码RdData1中声明为，std_logic_vector(31 downto 0)但对于 SRL，RdData1则用作RdData1(1 downto 31). 这会创建一个空范围，这会导致工具警告。

这必须更正为RdData1(31 downto 1).

SLL 和 SRL 的指令定义可以在此处查看MIPS 架构。

于 2013-09-06T10:12:14.040 回答