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DKirv's avatar
DKirv
Icon for New Contributor rankNew Contributor
6 years ago

How does Quartus Prime deal with arrays?

I am using VHDL to code a Deo nano SoC. This system has FPGA, CPU and ram. I am focused on the FPGA. I currently am reading data from an outside source and I load the data in a 300 element array. I then changed the array size to 3000 elements and recompiled. I copied the compilation report for both cases and I did not notice a difference in the resources. Where is the FPGA storing the array data and how much room do I have? I am self taught and it was my understanding that data was stored in a form of an IF THEN or similar statement.

4 Replies

  • sstrell's avatar
    sstrell
    Icon for Super Contributor rankSuper Contributor
    6 years ago

    It would help if you posted the code. Device resources get optimized away (or never synthesized at all) if it is determined they are not needed during compilation.

    #iwork4intel

  • DKirv's avatar
    DKirv
    Icon for New Contributor rankNew Contributor
    6 years ago

    Here is an example of my code for a larger array.

    Where are the elements in the array stored?

    type t_Memory is array (0 to 1023) of std_logic_vector(31 downto 0);

    signal my_array : t_Memory;

    signal my_index : integer range 0 to 1023 := 0;

    signal my_input : std_logic_vector(31 downto 0) ;

    if flag = 3 then

    my_index <= my_index + 1;

    my_array(my_index) <= my_input;

    end if;

    if my_index = 1022 then

    flag <= 4;

  • DKirv's avatar
    DKirv
    Icon for New Contributor rankNew Contributor
    6 years ago

    Yesterday, I was writing code and as I changed the parameters of an array, the RAM summary would change accordingly. Now the RAM appears to be utilized by the ALUs. Now I am out of ALU space. Is there a way to explicitly get QP to read/write array elements from RAM?

  • DKirv's avatar
    DKirv
    Icon for New Contributor rankNew Contributor
    6 years ago

    I found my problem. I had a runaway index.