--- Quote Start ---
Hello,
I'm having some trouble synthesizing my code, I'm running out of logic cells on my DE2 Altera board.
I want to use the values from 4 std_logic_vectors(7 downto 0) to retrieve the elements of an array, CollisionReg which consists of 119 std_logic_vectors(159 downto 0). I'm doing this by converting the std_logic_vectors to integer using to_integer( unsigned( some std_logic_vector ). If I remove the integer conversions, I can compile fine. I've also tried storing the conversion into some integer variable of a fixed range 0 to 160, but it doesn't help. Is there a reason why integer conversion is taking so many logic cells? Is there a better way for me to do this?
My code creates a matrix equal to the screen resolution and detects if a coordinate on the screen has been travelled before. Any help would be appreciated, thanks!
entity CoordinateMatrix is
port(
XHead: in std_logic_vector(7 downto 0);
YHead: in std_logic_vector(7 downto 0);
XTail: in std_logic_vector(7 downto 0);
YTail: in std_logic_vector(7 downto 0);
LoadCM: in std_logic;
initCM: in std_logic;
CLK: in std_logic;
didCollide: out std_logic);
end;
architecture behavioural of CoordinateMatrix is
type CMArray is array(119 downto 0) of std_logic_vector(159 downto 0);
signal CollisionReg: CMArray;
begin
collisionMatrix: process(CLK)
begin
if(rising_edge(clk)) then
if(LoadCM = '1') then
if(initCM = '1') then
-------********* PROBLEM HERE
didCollide <= CollisionReg(to_integer( unsigned( XHead)))(to_integer( unsigned( YHead))); --return old value
CollisionReg(to_integer( unsigned( XHead)))(to_integer( unsigned( YHead))) <= '1'; --update to already been here
CollisionReg(to_integer( unsigned( XTail)))(to_integer( unsigned( YTail))) <= '0'; --remove last pixel of snake
--------------------------------
else
for i in 119 downto 0 loop
for y in 159 downto 0 loop
if(i = 0 OR i = 119 OR y = 0 or y = 159) then --border always occupied
CollisionReg(i)(y) <= '1';
else
CollisionReg(i)(y) <= '0';
end if;
end loop;
end loop;
end if;
end if;
end if;
end process;
--- Quote End ---
you say if you remove integer conversion it is fine. I assume by that you mean you declare your inputs as integers, then you can just do that.
But that does not make sense because this conversion is a compile time issue that is settled at compilation and the final logic should be same.
I tried to compile your code and gave same resource whether I do conversions or not. As a side note it tells me that two of your inputs bit 7 are not driving anything.
Honored Contributor
