Subversion Repositories risc5x

--

-- Risc5x

-- www.OpenCores.Org - November 2001

--

--

-- This library is free software; you can distribute it and/or modify it

-- under the terms of the GNU Lesser General Public License as published

-- by the Free Software Foundation; either version 2.1 of the License, or

-- (at your option) any later version.

--

-- This library is distributed in the hope that it will be useful, but

-- WITHOUT ANY WARRANTY; without even the implied warranty of

-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

-- See the GNU Lesser General Public License for more details.

--

-- A RISC CPU core.

--

-- (c) Mike Johnson 2001. All Rights Reserved.

-- mikej@opencores.org for support or any other issues.

--

-- Revision list

--

-- version 1.0 initial opencores release

--

library ieee;

use ieee.std_logic_1164.all;

package pkg_risc5x is

  function slv_to_integer(x : std_logic_vector) return integer;

  function integer_to_slv(n, bits : integer) return std_logic_vector;

end;

package body pkg_risc5x is

  function slv_to_integer(x : std_logic_vector) return integer is

    variable n : integer := 0;

    variable failure : boolean := false;

  begin

    assert (x'high - x'low + 1) <= 31

        report "Range of sulv_to_integer argument exceeds integer range"

        severity error;

    for i in x'range loop

      n := n * 2;

      case x(i) is

        when '1' | 'H' => n := n + 1;

        when '0' | 'L' => null;

        when others =>

            -- failure := true;

            null;

      end case;

    end loop;

    assert not failure

      report "sulv_to_integer cannot convert indefinite std_logic_vector"

      severity error;

    if failure then

      return 0;

    else

      return n;

    end if;

  end slv_to_integer;

  function integer_to_slv(n, bits : integer) return std_logic_vector is

    variable x : std_logic_vector(bits-1 downto 0) := (others => '0');

    variable tempn : integer := n;

  begin

    for i in x'reverse_range loop

      if (tempn mod 2) = 1 then

        x(i) := '1';

      end if;

      tempn := tempn / 2;

    end loop;

    return x;

  end integer_to_slv;

end;