Subversion Repositories lxp32

---------------------------------------------------------------------

-- Complementor

--

-- Part of the LXP32 CPU

--

-- Copyright (c) 2016 by Alex I. Kuznetsov

--

-- Computes a 2's complement of its input. Used as an auxiliary

-- unit in the divider.

---------------------------------------------------------------------

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

entity lxp32_compl is

        port(

                clk_i: in std_logic;

                compl_i: in std_logic;

                d_i: in std_logic_vector(31 downto 0);

                d_o: out std_logic_vector(31 downto 0)

        );

end entity;

architecture rtl of lxp32_compl is

signal d_prepared: unsigned(d_i'range);

signal sum_low: unsigned(16 downto 0);

signal d_high: unsigned(15 downto 0);

signal sum_high: unsigned(15 downto 0);

begin

d_prepared_gen: for i in d_prepared'range generate

        d_prepared(i)<=d_i(i) xor compl_i;

end generate;

process (clk_i) is

begin

        if rising_edge(clk_i) then

                sum_low<=("0"&d_prepared(15 downto 0))+(to_unsigned(0,16)&compl_i);

                d_high<=d_prepared(31 downto 16);

        end if;

end process;

sum_high<=d_high+(to_unsigned(0,15)&sum_low(sum_low'high));

d_o<=std_logic_vector(sum_high&sum_low(15 downto 0));

end architecture;