代码：
library IEEE;
use IEEE.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.std_logic_unsigned.all;
entity decoder10 is
port( in_data: in STD_LOGIC_VECTOR (7 downto 0);
clk : in STD_LOGIC;
out_data: out STD_LOGIC_VECTOR (7 downto 0));
end decoder10;
architecture behavioral of decoder10 is
signal int_bus1 : STD_LOGIC_VECTOR (63 downto 0);
signal int_bus2 : STD_LOGIC_VECTOR (63 downto 0);
signal int_bus3 : STD_LOGIC_VECTOR (31 downto 0);
signal lower : STD_LOGIC_VECTOR (31 downto 0);
signal higher : STD_LOGIC_VECTOR (31 downto 0);
signal intermid : STD_LOGIC_VECTOR (31 downto 0);
signal curr_key : STD_LOGIC_VECTOR (31 downto 0);
signal got_data: std_logic; --data written in
signal variable_test: std_logic:= '0';
signal n_ready: std_logic; --code assembled
signal k_ready: std_logic; --key selected
signal k_added: std_logic; --key added
signal sub_ready: std_logic; --blocks substituted
signal sh_ready: std_logic; --shift done
signal xor_ready: std_logic; --xor done
signal out_ready: std_logic; --ready for output
signal sent_data: std_logic; --data written out
signal start_again: std_logic; --start the main step again
type arr is array (0 to 15) of std_logic_vector(31 downto 0);
type key is array (0 to 7) of std_logic_vector(31 downto 0);
type key_num is array (0 to 31) of integer;
signal key_it : key_num := (0,1,2,3,4,5,6,7,
7,6,5,4,3,2,1,0,
7,6,5,4,3,2,1,0,
7,6,5,4,3,2,1,0);
signal tab : arr := (X"00000001",
X"00000002",
X"00000003",
X"00000004",
X"00000005",
X"00000006",
X"00000007",
X"00000008",
X"00000009",
X"0000000a",
X"0000000b",
X"0000000c",
X"0000000d",
X"0000000e",
X"0000000f",
X"00000000");
signal tab_key : key := (X"00000007",
X"00000006",
X"00000005",
X"00000004",
X"00000003",
X"00000002",
X"00000001",
X"00000000");
component adder is
port( dataa : IN STD_LOGIC_VECTOR (31 DOWNTO 0);
datab : IN STD_LOGIC_VECTOR (31 DOWNTO 0);
result : OUT STD_LOGIC_VECTOR (31 DOWNTO 0));
END component;
begin
add1: adder
port map (lower, curr_key, int_bus3);
process (clk, in_data)
variable i: INTEGER := 0;
variable j: INTEGER := 0;
variable k: INTEGER := 0;
begin
-- assembling input code into one piece
if (rising_edge(clk)) then
if (i<8) then
int_bus1(63 downto 56)<=in_data;
got_data <= '1';
n_ready <= '0';
if (got_data = '1') then
--shift right 8 bits
int_bus1(55 downto 0) <= int_bus1(63 downto 8);
i := i + 1;
got_data <= '0';
end if;
end if;
if (i = 8 and n_ready = '0' and out_ready = '0') then
lower<=int_bus1(31 downto 0);
higher<=int_bus1(63 downto 32);
n_ready <= '1';
start_again <= '1';
end if;
end if;
if (n_ready ='1') then
-- base encryption step
if (rising_edge(clk)) then
if (j <32 and start_again = '1') then
-- key/step dependence
curr_key <= tab_key(key_it(j));
k_ready <= '1';
start_again <= '0';
end if;
if (k_ready = '1') then
lower <= curr_key + lower;
k_added <= '1';
k_ready <='0';
end if;
if (k_added = '1') then
--block substitution
lower(3 downto 0) <= tab(CONV_INTEGER(lower(3 downto 0)))(3 downto 0);
lower(7 downto 4) <= tab(CONV_INTEGER(lower(7 downto 4)))(7 downto 4);
lower(11 downto 8) <= tab(CONV_INTEGER(lower(11 downto 8)))(11 downto 8);
lower(15 downto 12) <= tab(CONV_INTEGER(lower(15 downto 12)))(15 downto 12);
lower(19 downto 16) <= tab(CONV_INTEGER(lower(19 downto 16)))(19 downto 16);
lower(23 downto 20) <= tab(CONV_INTEGER(lower(23 downto 20)))(23 downto 20);
lower(27 downto 24) <= tab(CONV_INTEGER(lower(27 downto 24)))(27 downto 24);
lower(31 downto 28) <= tab(CONV_INTEGER(lower(31 downto 28)))(31 downto 28);
sub_ready <= '1';
k_added <= '0';
end if;
if (sub_ready = '1') then
--shift 11 bits right cyclically
lower(31 downto 21) <= lower(10 downto 0);
lower(20 downto 0) <= lower(31 downto 11);
sh_ready<= '1';
sub_ready <= '0';
end if;
if (sh_ready = '1') then
higher <= lower xor higher;
lower <= higher;
sh_ready<= '0';
j:=j+1;
start_again <= '1';
out_ready <= '0';
end if;
end if;
end if;
if (rising_edge(clk)) then
if (j = 32 and out_ready = '0') then
j:=j+1;
variable_test <= '1'; --artifact of testing the behavior of variables
end if;
end if;
-- assembling output code into one piece
if (rising_edge(clk)) then
if (out_ready = '0' and variable_test = '1') then
int_bus2 (63 downto 32) <= higher;
int_bus2 (31 downto 0) <= lower;
out_ready <= '1';
n_ready <= '0';
end if;
if (out_ready = '1' and k<8) then
out_data<=int_bus2(7 downto 0);
sent_data <= '1';
if (sent_data ='1') then
--shift right 8 bits
int_bus2(55 downto 0) <= int_bus2(63 downto 8);
k := k + 1;
sent_data <= '0';
end if;
end if;
end if;
end process;
end behavioral;
我收到以下错误：
错误（10821）：decoder10.vhd（106）处的HDL错误：无法推断
start_again的寄存器，因为其行为与任何支持的寄存器模型不匹配
信息（10041）：在decoder10.vhd（75）的start_again的推断锁存器 错误（10821）：decoder10.vhd（106）处的HDL错误：无法推断higher[0]的寄存器，因为其行为与任何支持的寄存器模型不匹配
信息（10041）：在decoder10.vhd（75）的higher[0]的推断锁存器 （这仍然是“更高”的前18位）
为什么不合成？为什么不能只推断出higher的前18位？
答案 0 :(得分：1)
这很可能是因为您的时钟使能优先于您的时钟，并且没有FPGA硬件允许这样做。无论何时编写用于综合的代码，您都需要考虑这是否可以实际映射到底层硬件。 而不是
if (n_ready ='1') then
-- base encryption step
if (rising_edge(clk)) then
(...)
尝试：
if(rising_edge(clk)) then
if(n_ready = '1') then
(...)
看看Get your priorities right - 它是为Xilinx FPGA编写的，但我猜这类似的东西也适用于其他产品。
答案 1 :(得分：0)
sonicwave的第一个答案在所有体系结构中都不是严格正确的，尽管在这种情况下我认为是正确的。
如果后面有一个边缘可以通过门控时钟来实现，而不是这样做是一个好主意或是否支持所有类型的FPGA或CPLD架构。
一些提示： 将tab和tab_key更改为常量。它们从未被分配，所以不需要信号。将它们作为信号可能意味着它们在某些架构中是单元化的。
整个事情应该使用进程，而不是使用顺序逻辑。这导致'推断锁存'错误，因为取决于通过代码start_again的路径可能会也可能不会被写入。为了避免推断锁存器，请确保通过所有路径写入信号或在进程内部计时。
您需要记住，VHDL不是一种编程语言，它是一种描述语言。除非系统是同步的，否则所有行都是同时执行的。例如在第147行，你有两条线同时操纵更高和更低。
如果你告诉我你想要达到的目的，我可以为你重新写一遍。