How can i write this if
statement condition in better way?
if ((data_in(8 downto 1)=x"70") or (data_in(8 downto 1)=x"69") or
(data_in(8 downto 1)=x"72") or (data_in(8 downto 1)=x"7A") or
(data_in(8 downto 1)=x"6B") or (data_in(8 downto 1)=x"73") or
(data_in(8 downto 1)=x"74") or (data_in(8 downto 1)=x"6C") or
(data_in(8 downto 1)=x"75") or (data_in(8 downto 1)=x"7D")) then
data_make_code <= data_in (8 downto 1); -- enter key to buffer
wrong_data <='0';
cnt_bit :=0;
-- if valid key then
current_state <= break_code_receive;
elsif
...
end if;
A case
statement can be used to compare with multiple values, and the others
part of the case
can then be used as "else"
, like:
case data_in(8 downto 1) is
when x"70" | x"69" | x"72" | x"7A" | x"6B" |
x"73" | x"74" | x"6C" | x"75" | x"7D" =>
... -- if part of code
when others =>
... -- else part of code
end case;
An alternative method is to use an array
of std_logic_vector
with the values, and then make a function that can determine if the data_in
value equals either of the values in the array. The type
and function
declarations can then either be in the architecture
or process
declaration section. The code in VHDL-2008 can then look like:
type slv_array is array (natural range <>) of std_logic_vector;
function in_array(val : std_logic_vector; set : slv_array) return boolean is
begin
for idx in set'range loop
if val = set(idx) then
return TRUE;
end if;
end loop;
return FALSE;
end function;
...
if in_array(data_in, (x"70", x"69", x"72", x"7A", x"6B",
x"73", x"74", x"6C", x"75", x"7D")) then
... -- if part of code
else
... -- else part of code
end if;
The alternative method requires a few declarations, but is more general applicable.