LIBRARY ieee; USE ieee.std_logic_1164.ALL; ENTITY piso IS PORT(DATA_IN :IN STD_LOGIC_VECTOR(3 DOWNTO 0); CLK, nLOAD, EN :IN STD_LOGIC; DATA_OUT :OUT STD_LOGIC); END piso; ARCHITECTURE a OF piso IS BEGIN SIGNAL Q: STD_LOGIC_VECTOR(3 DOWNTO 0); PROCESS(nLOAD,CLK,EN) BEGIN IF EN='0' THEN Q<="0000"; DATA_OUT <= '0'; ELSEIF CLK'EVENT AND CLK = '1' THEN IF nLOAD = '0' THEN Q <= DATA_IN; DATA_OUT <= '0'; ELSE FOR I IN 1 TO 3 LOOP Q(I) <= Q(I-1); DATA_OUT <= Q(3); END IF; END IF; END PROCESS ; END a;找出错误并改正
时间: 2024-03-17 20:41:15 浏览: 72
vhdl.zip_All Out_vhdl library use
以下是修改后的代码,主要是修复了逻辑错误和语法错误:
```
LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
ENTITY piso IS
PORT(
DATA_IN :IN STD_LOGIC_VECTOR(3 DOWNTO 0);
CLK, nLOAD, EN :IN STD_LOGIC;
DATA_OUT :OUT STD_LOGIC
);
END piso;
ARCHITECTURE a OF piso IS
SIGNAL Q: STD_LOGIC_VECTOR(3 DOWNTO 0);
BEGIN
PROCESS(nLOAD,CLK,EN)
BEGIN
IF EN = '0' THEN
Q <= "0000";
DATA_OUT <= '0';
ELSE
IF CLK'EVENT AND CLK = '1' THEN
IF nLOAD = '0' THEN
Q <= DATA_IN;
DATA_OUT <= '0';
ELSE
FOR I IN 3 DOWNTO 1 LOOP
Q(I) <= Q(I-1);
END LOOP;
Q(0) <= DATA_IN;
DATA_OUT <= Q(3);
END IF;
END IF;
END IF;
END PROCESS;
END a;
```
修改后的代码中,主要修复了以下几个问题:
1. 在逻辑判断语句中,应该使用 AND 连接两个条件,而不是将它们分开;
2. 在 FOR 循环中,应该从高位到低位循环,因为在移位时需要从高位开始移动;
3. 在 FOR 循环中,应该增加一条语句将 DATA_IN 的值写入 Q(0) 中。
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