Forum Discussion
Altera_Forum
Honored Contributor
Honored ContributorCompare two byte arrays
I have a list of commands and a command received from UART.
type commands is array(0 to COM_SIZE) of std_logic_vector(7 downto 0);
signal commands_list : commands(0 to COM_COUNT) :=
(
x"73746F700000", --stop
x"667764000000", --fwd
x"726576000000" --rev
);
type com_str is array (0 to COM_SIZE) of std_logic_vector(7 downto 0);
signal command : com_str;
for i in 0 to COM_COUNT loop
if (commands_list(i) /= command) then
--do something
end if;
end loop;
for i in 0 to COM_COUNT loop
for j in 0 to name_len loop
if (commands_list(i)(j) /= command(j)) then
--do something
end if;
end loop;
end loop;
6 Replies
Altera_ForumIn the first case, you're comparing a std_logic_vector to an array of std_logic_vector. Doesn't work.
In the 2nd case, you're comparing a std_logic to a std_logic_vector. Doesn't work either. I assume the problem is that the type of com_str is wrong. I guess it should really be this:
That would, from the context, make more sense to me.signal command: std_logic_vector(7 downto 0);- Altera_Forum--- Quote Start --- In the first case, you're comparing a std_logic_vector to an array of std_logic_vector. Doesn't work. In the 2nd case, you're comparing a std_logic to a std_logic_vector. Doesn't work either. I assume the problem is that the type of com_str is wrong. I guess it should really be this:
That would, from the context, make more sense to me. --- Quote End --- 'command' is not a char - it's array of chars. this way - command: std_logic_vector(7 downto 0); - it holds only one char, and I need to get array of chars from terminal.signal command: std_logic_vector(7 downto 0); - Altera_Forum
Ah, now I understand. So, a "char" in your case is supposed to be a std_logic_vector with 8 bits, right?
But then, "commands" should be an array of array of std_logic_vector(7 downto 0). You're missing one level of arrays. You try to initialize a std_logic_vector(7 downto 0) with "x"73746F700000", where "73746F700000" is 48 bits. I wonder why the compiler doesn't complain, but you have to fix that first. - Altera_Forum--- Quote Start --- Ah, now I understand. So, a "char" in your case is supposed to be a std_logic_vector with 8 bits, right? But then, "commands" should be an array of array of std_logic_vector(7 downto 0). You're missing one level of arrays. You try to initialize a std_logic_vector(7 downto 0) with "x"73746F700000", where "73746F700000" is 48 bits. I wonder why the compiler doesn't complain, but you have to fix that first. --- Quote End --- Yes. You are right. I need array of array - each member of array is array of chars - a command in the list. But how I should initialize it? type commands is array(0 to 6) of std_logic_vector(7 downto 0); signal commands_list : commands(0 to 2) := ( x"73746F700000", --stop x"667764000000", --fwd x"726576000000" --rev ); if array(0 to 6) then x"73746F700000" is 7 elements 73 74 6F 70 00 00 00. I was trying this way
But I get an error Error (10515): VHDL type mismatch error at parser.vhd(71): std_ulogic type does not match string literalsignal commands_list : commands_l(2 downto 0) := ( 0 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --stop 1 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --fwd 2 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21") --rev ); - Altera_Forum
I agree that your approach looks correct now.
However, without seeing the complete code, I cannot tell what's wrong. I have no clue what line 71 is, and I have no clue how the signals and types that are references in that line are declared. Keep that in mind before posting anything else. Anyway, here's some code that passes synthesis, and should give you the right pointers:type command_type is array(0 to 5) of std_logic_vector(7 downto 0); type commands_type is array(0 to 2) of command_type; signal commands: commands_type := ( 0 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --stop 1 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --fwd 2 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21") --rev ); - Altera_Forum--- Quote Start --- I agree that your approach looks correct now. However, without seeing the complete code, I cannot tell what's wrong. I have no clue what line 71 is, and I have no clue how the signals and types that are references in that line are declared. Keep that in mind before posting anything else. Anyway, here's some code that passes synthesis, and should give you the right pointers:
--- Quote End --- The problem was different types. VHDL is very strict about it. This way it workstype command_type is array(0 to 5) of std_logic_vector(7 downto 0); type commands_type is array(0 to 2) of command_type; signal commands: commands_type := ( 0 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --stop 1 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --fwd 2 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21") --rev );type str_t is array(integer range<>) of std_logic_vector(7 downto 0); type commands is array(integer range<>) of str_t(0 to COM_SIZE); constant commands_list : commands(0 to COM_COUNT) := ( 0 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --stop 1 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21"), --fwd 2 => (0 => x"00", 1 => x"01", 2 => x"10", 3 => x"11", 4 => x"20", 5 => x"21") --rev ); type rx_buff_str is array (0 to RX_BUF_SIZE-1) of std_logic_vector(7 downto 0); signal rx_uart_buf : rx_buff_str; signal rx_command : str_t(0 to COM_SIZE); ---------------------------------- --------------------------------- --------------------------------- for i in 0 to COM_COUNT loop if (commands_list(i) /= rx_command) then end if; end loop;
