converting std_logic_vector to integer

Discussion in 'VHDL' started by vedpsingh, Aug 11, 2005.

  1. vedpsingh

    vedpsingh Guest

    Hi all,
    The code given below has perfectly compiled, but is not giving integer
    What am I doing wrong?


    LIBRARY ieee;
    USE ieee.std_logic_1164.ALL;
    USE ieee.std_logic_arith.ALL;
    USE ieee.std_logic_unsigned.ALL;

    ENTITY conv_vec_int IS

    PORT ( a : IN std_logic_vector(7 downto 0);
    b : OUT integer range 0 to 255
    END conv_vec_int;

    ARCHITECTURE behav_conv_vec_int OF conv_vec_int IS

    SIGNAL ai : std_logic_vector(7 downto 0);
    SIGNAL bi : integer range 0 to 255;


    ai <= a;

    -- convert a from std_logic_vector to integer

    bi <= bi* (conv_integer(ai));

    END behav_conv_vec_int;
    vedpsingh, Aug 11, 2005
    1. Advertisements

  2. Take a look through the FAQ, there are a few things wrong with your code.
    Not to mention that this should be a function, not a component, and whether
    a function is really needed in such a simple case as this.

    I'm not going to give too much in the way of help... More fun to figure it
    out IMHO.
    is the URL to get you started.
    Benjamin Todd, Aug 11, 2005
    1. Advertisements

  3. vedpsingh

    Neo Guest

    Your variable bi is not assigned, so it will always have the initial
    value zero making your output also zero. the variables ai and bi are
    actually unnecessary. by the way, what is the need for a module when
    you can simply use the conversion function directly.
    Neo, Aug 11, 2005
  4. vedpsingh

    vedpsingh Guest

    by the way, what is the need for a module when
    I hope these funtions are synthesizable ??
    vedpsingh, Aug 11, 2005
  5. In this case std_logic_vector vs integer is not a question of whether it can
    be synthesised. Fundamentally hardware has no notion of integer, everything
    is wires and logic, '1' and '0'.
    i.e. using integer instead of std_logic_vector simply allows the code to be
    easier to read and more readily interpreted (in various cases) by the
    synthesis tool.
    Benjamin Todd, Aug 11, 2005
  6. vedpsingh

    vizziee Guest

    Conversion functions are programming utilities and don't consume any
    hardware on chip. You can write a few simple programs to check this.

    vizziee, Aug 16, 2005
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.