Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
9 years ago

Problem converting to integer

I have a code 


LIBRARY ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
use ieee.std_logic_arith.all;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity REG_FILE is
port
(
    REG_ADDR_IN     : in std_logic_vector(15 downto 0);
    -- some code    
);
end REG_FILE;
architecture behavior of REG_FILE is
    --some code
    signal mailbox_idx : integer := 0;
process(REG_CLK)
begin
      -- some code
     mailbox_idx <= to_integer(to_unsigned(REG_ADDR_IN));
end process;
end behavior;

And result 


mailbox_idx <= to_integer(REG_ADDR_IN);
Error (10405): VHDL error at reg_file.vhd(75): can't determine type of object at or near identifier "to_integer" -- found 0 possible types
or this way
mailbox_idx <= to_integer(to_unsigned(REG_ADDR_IN));
Error (10476): VHDL error at reg_file.vhd(75): type of identifier "REG_ADDR_IN" does not agree with its usage as "natural" type
Error (10346): VHDL error at reg_file.vhd(75): formal port or parameter "SIZE" must have actual or default value

Where is a problem?

4 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    Hi,

    Read function description:

    function TO_UNSIGNED ( ARG,SIZE: NATURAL) return UNSIGNED;

    -- Result subtype: UNSIGNED (SIZE-1 downto 0)

    -- Result: Converts a non-negative INTEGER to an UNSIGNED vector with

    -- the specified SIZE.

    As you can see you did not specify "SIZE" parameter and your REG_ADDR_IN has to be integer type also.

    I recomend googling about libraries and packages usage in VHDL. I usualy use just two libraries:

    use ieee.std_logic_1164.all;

    use ieee.numeric_std.all;

    and if you need some type conversion use:

    https://www.doulos.com/knowhow/vhdl_designers_guide/numeric_std/ (https://www.doulos.com/knowhow/vhdl_designers_guide/numeric_std/)
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    9 years ago

    --- Quote Start ---

    Yes. The problem was use ieee.std_logic_arith.all; Thank you.

    --- Quote End ---

    Yes - std_logic_arith and numeric_std have the same functions and types declared, so they clash, and neither of them are visible. std_logic_arith is not a standard VHDL package (neither is std_logic_unsigned), while numeric_std is.

    I recommend deleting std_logic_arith.