我有以下问题：
我有一台为我的 SPARTAN 3AN FPGA 提供输入的 PC，我希望获取这些输入，将它们放入 std_logic_vector，然后将它们转换为整数。指令被分成“n”条指令，每条指令有 32 位。我需要将前三位放在一个整数中，接下来的 28 位放在另一个整数中，最后一个是“最后一条指令标志”。所以，我有两个 100 个整数的数组，我将在其中放入指令（100 是限制）。如果“最后一条指令标志”为 1，则整个操作应该停止。
程序没有正确合成，所以我做了一个模拟。我发现了问题，但我不知道如何解决，所以我需要你的帮助。这是代码和模拟输出：
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
USE IEEE.NUMERIC_STD.all;
entity BinaryDecimalConv is
end BinaryDecimalConv;
architecture Behavioral of BinaryDecimalConv is
type int_array is array (100 downto 0) of integer;
signal clkcnt: integer :=0;
signal fbaud: integer;
signal lastnumflag: std_logic:='0';
signal clk: std_logic;
signal PLCinput: std_logic;
signal init: std_logic;
signal BusyIN: std_logic;
signal BusyOutSignal: std_logic;
signal InnerBusyOut: std_logic;
signal cnt: integer :=0;
signal fbaut: integer :=0;
signal pre_int: std_logic_vector (31 downto 0) := (others => '0');
signal pre_spec_num: int_array := (others =>0);
signal cylinder: int_array := (others => 0);
signal InnerNumLength: integer:=0;
signal num_length: integer:=0;
begin
CLOCKK: Process is
begin
clk<='0';
wait for 10 ns;
clk<='1';
wait for 10 ns;
end process CLOCKK;
fbaud <=5208;
BusyIN <='0';
init <='0';
PLC: Process is
variable PrePLC: std_logic_vector(159 downto 0):="1010101010101010101010101001010010101010101010101010101010010100101010101010101010101010100101001010101010101010101010101001010010101010101010101010101010010101"; -- 1 with 100, 5 with 200, 5 2ith 200, 3 with 300, 4 with 750
begin
PLCinput<=PrePLC(159);
PrePLC:= PrePLC(158 downto 1) & '0';
wait for 104166 ns;
end process;
LastNum: process (LastNumFlag) is
begin
if LastNumFlag = '1' then
BusyOutSignal <='1';
InnerBusyOut <='1';
else
BusyOutSignal <='0';
InnerBusyOut <='0';
end if;
end process LastNum;
DecoderAndAcquirer: process (PLCinput, BusyIN, InnerBusyOut,clk) is
begin
if (clk'event and clk='1') then -- If rising edge on clock
if ((BusyIN='0') and (InnerBusyOut='0') and (init='0')) then -- Check if FPGA and PLC are ready to exchange information and if init is done
if (clkcnt = fbaud/2) then -- If clkcnt is equal to half of the duration of the input bit then
pre_int(31) <= PLCinput; -- Initialize the last digit of pre_int
cnt <= cnt+1; -- Incrementing cnt => going towards bit 2
clkcnt <=clkcnt+1; -- Incrementing clkcnt so you can exit this block
if (cnt<32) then -- Checking if not last bit
pre_int <= '0' & pre_int(31 downto 1); -- If not last bit, shift number to right
else -- else
cnt <=0; -- reset cnt to start with next instruction
if (pre_int(0)='1') then -- Check if last digit is one
LastNumFlag <= '1'; -- If last digit is one, stop acquiring instructions
else
LastNumFlag <='0';
end if;
pre_spec_num(InnerNumLength) <= to_integer(unsigned(pre_int(28 downto 1))); -- Conversion from binary to decimal for instruction
cylinder(InnerNumLength) <= to_integer(unsigned(pre_int(31 downto 29))); -- Conversion from binary to decimal for the number of cylinder
InnerNumLength <= InnerNumLength +1; -- Incrementing the number of instructions
num_length <= InnerNumLength;
end if;
elsif (clkcnt = fbaud) then -- If clkcnt has reached the entire length of the input bit
clkcnt <= 0; -- set clkcnt to zero so the process can start from beginning.
else -- If clkcnt is less than or more than half of the entire duration, but surely
clkcnt <= clkcnt +1; -- less than the entire duration, then increment the value of the clkcnt.
end if;
end if;
end if;
end process DecoderAndAcquirer;
end Behavioral;
问题是，如图所示，当 cnt 改变时，指令的第 31 位没有任何反应。任何想法为什么？
谢谢，博扬
