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\begin{document}
\begin{titlepage}
\begin{center}
\linespread{1.2}\huge {\bfseries Fudan University}\\[1cm]
\linespread{1}
\includegraphics[width=10cm]{fudan-name.pdf}\\[3cm]
\linespread{1.9}\huge {\bfseries 可编程器件与硬件描述语言}\\
\linespread{1.9}\LARGE {\bfseries 作业报告}\\[2.5cm]
{\Large 姓名：名字}\\[0.3cm]
\Large 学号：123456789\\[4cm]
\large 2021年11月1日
\end{center}
\end{titlepage}
\section{优先编码器}
设计一个BCD的优先编码器电路，输入为10个开关的状态，要求输出开
关对应的编码。输出编码用4位表示，第一个开关为0时，输出为0000时，第二个开关为0时，输出为0001时，...... 第10个开关为0时，输出为1001。第10个开关的优先级最高。当没有按键按下时，输出信号E为1。有按键按下时，输出信号E为0。
%题干
\subsection{顶层说明}
\begin{figure}[H]
\centering
\includegraphics[width=8cm]{Q1TOP.png} %这里换成你的图片
\caption{元件示意图}
\end{figure}
Input[9:0]为十个开关，其中Input(9)的优先级最高，Output[3:0]为四位输出，E表示是否有按键被按下。
\begin{figure}[H]
\centering
\includegraphics[width=15cm]{Q1RTL.png}
\caption{RTL图}
\end{figure}
\subsection{每个宏单元如何实现（对所写代码的说明）}
代码如下：
\begin{minted}[mathescape,
linenos,
numbersep=5pt,
gobble=0,
frame=single,
fontfamily=courier,
framesep=4mm]{vhdl}
---------------------------------------------------
-- 10-bit Priority encoder
-- by Zhang Ke, 2021/10/30 9:26PM
---------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
---------------------------------------------------
entity BCD_Encoder10 is
port (
Input : in std_logic_vector(9 downto 0);
Output : out std_logic_vector(3 downto 0);
E : out std_logic
);
end BCD_Encoder10;
---------------------------------------------------
architecture rtl of BCD_Encoder10 is
begin
process (Input)
begin
if (Input(9) = '0') then
Output <= "1001";
E <= '0';
elsif (Input(8) = '0') then
Output <= "1000";
E <= '0';
elsif (Input(7) = '0') then
Output <= "0111";
E <= '0';
elsif (Input(6) = '0') then
Output <= "0110";
E <= '0';
elsif (Input(5) = '0') then
Output <= "0101";
E <= '0';
elsif (Input(4) = '0') then
Output <= "0100";
E <= '0';
elsif (Input(3) = '0') then
Output <= "0011";
E <= '0';
elsif (Input(2) = '0') then
Output <= "0010";
E <= '0';
elsif (Input(1) = '0') then
Output <= "0001";
E <= '0';
elsif (Input(0) = '0') then
Output <= "0000";
E <= '0';
else
Output <= "XXXX";
E <= '1';
end if;
end process;
end rtl;
\end{minted}
以上代码中，将元件输入Input定义为10位的标准逻辑向量类型，输出E和Output分别定义为标准逻辑位和4位的标准逻辑向量类型。具体architecture实现中使用IF语句进行状态判断并且输出。\\
\subsection{时序仿真结果}
编写Test Bench文件如下：
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linenos,
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frame=single,
fontfamily=courier,
framesep=4mm]{vhdl}
---------------------------------------------------
-- Test Bench for 10-bit Priority encoder
-- by Zhang Ke, 2021/10/30 9:57PM
---------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
---------------------------------------------------
entity Q1_BCD_Encoder_tb is
end Q1_BCD_Encoder_tb;
---------------------------------------------------
architecture tbbehv of Q1_BCD_Encoder_tb is
component BCD_Encoder10
port (
Input : in std_logic_vector(9 downto 0);
Output : out std_logic_vector(3 downto 0);
E : out std_logic
);
end component;
signal Input : std_logic_vector(9 downto 0) := "0000000000";
signal Output : std_logic_vector(3 downto 0);
signal E : std_logic;
begin
U_BCD : BCD_Encoder10 port map(Input, Output, E);
inputpc : process
begin
Input <= "0000000000"; wait for 20 ns; Input <= "1000000000"; wait for 20 ns;
Input <= "1100000000"; wait for 20 ns; Input <= "1110000000"; wait for 20 ns;
Input <= "1111000000"; wait for 20 ns; Input <= "1111100000"; wait for 20 ns;
Input <= "1111110000"; wait for 20 ns; Input <= "1111111000"; wait for 20 ns;
Input <= "1111111100"; wait for 20 ns; Input <= "1111111110"; wait for 20 ns;
Input <= "1111111111"; wait for 20 ns; Input <= "1001100000"; wait for 20 ns;
Input <= "1110100000"; wait for 20 ns; Input <= "1111100100"; wait for 20 ns;
Input <= "1111011100";
wait;
end process;
end architecture;
\end{minted}
使用上述Test Bench文件进行仿真，波形图如下：
\begin{figure}[H]
\centering
\includegraphics[width=17.5cm]{Q1BL.png}
\caption{BCD优先编码器时序仿真波形}
\end{figure}
\end{document}