Subversion Repositories potato

-- The Potato Processor - A simple processor for FPGAs

-- (c) Kristian Klomsten Skordal 2014 <kristian.skordal@wafflemail.net>

-- Report bugs and issues on <http://opencores.org/project,potato,bugtracker>

library ieee;

use ieee.std_logic_1164.all;

use work.pp_types.all;

use work.pp_constants.all;

package pp_utilities is

        --! Converts a boolean to an std_logic.

        function to_std_logic(input : in boolean) return std_logic;

        -- Checks if a number is 2^n:

        function is_pow2(input : in natural) return boolean;

        --! Calculates log2 with integers.

        function log2(input : in natural) return natural;

        -- Gets the value of the sel signals to the wishbone interconnect for the specified

        -- operand size and address.

        function wb_get_data_sel(size : in std_logic_vector(1 downto 0); address : in std_logic_vector)

                return std_logic_vector;

end package pp_utilities;

package body pp_utilities is

        function to_std_logic(input : in boolean) return std_logic is

        begin

                if input then

                        return '1';

                else

                        return '0';

                end if;

        end function to_std_logic;

        function is_pow2(input : in natural) return boolean is

                variable c : natural := 1;

        begin

                for i in 0 to 30 loop -- FIXME: Simulator complains about 2^31 being out of range!

                        if input = i then

                                return true;

                        end if;

                        c := c * 2;

                end loop;

                return false;

        end function is_pow2;

        function log2(input : in natural) return natural is

                variable retval : natural := 0;

                variable temp   : natural := input;

        begin

                while temp > 1 loop

                        retval := retval + 1;

                        temp := temp / 2;

                end loop;

                return retval;

        end function log2;

        function wb_get_data_sel(size : in std_logic_vector(1 downto 0); address : in std_logic_vector)

                return std_logic_vector is

        begin

                case size is

                        when b"01" =>

                                case address(1 downto 0) is

                                        when b"00" =>

                                                return b"0001";

                                        when b"01" =>

                                                return b"0010";

                                        when b"10" =>

                                                return b"0100";

                                        when b"11" =>

                                                return b"1000";

                                        when others =>

                                                return b"0001";

                                end case;

                        when b"10" =>

                                if address(1) = '0' then

                                        return b"0011";

                                else

                                        return b"1100";

                                end if;

                        when others =>

                                return b"1111";

                end case;

        end function wb_get_data_sel;

end package body pp_utilities;