Subversion Repositories mini_aes

-- $Id: xtime.vhdl,v 1.1.1.1 2005-12-06 02:48:34 arif_endro Exp $
-------------------------------------------------------------------------------
-- Title       : Xtime manipulations
-- Project     : Mini AES 128 
-------------------------------------------------------------------------------
-- File        : xtime.vhdl
-- Author      : "Arif E. Nugroho" <arif_endro@yahoo.com>
-- Created     : 2005/12/03
-- Last update : 
-- Simulators  : ModelSim SE PLUS 6.0
-- Synthesizers: ISE Xilinx 6.3i
-- Target      : 
-------------------------------------------------------------------------------
-- Description : Xtime manipulation used in AES operations.
-------------------------------------------------------------------------------
-- Copyright (C) 2005 Arif E. Nugroho
-- This VHDL design file is an open design; you can redistribute it and/or
-- modify it and/or implement it after contacting the author
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
-- 
--         THIS SOURCE FILE MAY BE USED AND DISTRIBUTED WITHOUT RESTRICTION
-- PROVIDED THAT THIS COPYRIGHT STATEMENT IS NOT REMOVED FROM THE FILE AND THAT
-- ANY DERIVATIVE WORK CONTAINS THE ORIGINAL COPYRIGHT NOTICE AND THE
-- ASSOCIATED DISCLAIMER.
-- 
-------------------------------------------------------------------------------
-- 
--         THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
-- IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
-- MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
-- EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-- SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
-- OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
-- WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
-- OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
-- ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-- 
-------------------------------------------------------------------------------
 
library ieee;
use ieee.std_logic_1164.all;
 
package xtime_pkg is
 
  function xtime_2 ( b : std_logic_vector ) return std_logic_vector;
  function xtime_4 ( c : std_logic_vector ) return std_logic_vector;
  function xtime_8 ( d : std_logic_vector ) return std_logic_vector;
 
end xtime_pkg;
 
package body xtime_pkg is
 
  function xtime_2   ( b : std_logic_vector ) return std_logic_vector is
     variable xtime_2_v  : std_logic_vector (07 downto 00) := ( B"0000_0000" );
     begin
        xtime_2_v := (  b(6 downto 4)                     -- 7,6,5
                     & (b(3 downto 2) xor (b(7) & b(7)))  -- 4,3
                     &  b(1)                              -- 2
                     & (b(0) xor b(7))                    -- 1
                     &  b(7));                            -- 0
     return xtime_2_v;
  end xtime_2;
 
  function xtime_4  ( c : std_logic_vector ) return std_logic_vector is
     variable xtime_4_v : std_logic_vector (07 downto 00) := ( B"0000_0000" );
     begin
        xtime_4_v := (  c(5)                             -- 7
                     &  c(4)                             -- 6
                     & (c(3) xor c(7))                   -- 5
                     & (c(2) xor c(7) xor c(6))          -- 4
                     & (c(1) xor c(6))                   -- 3
                     & (c(0) xor c(7))                   -- 2
                     & (c(7) xor c(6))                   -- 1
                     &  c(6));                           --
     return xtime_4_v;
  end xtime_4;
 
  function xtime_8  ( d : std_logic_vector ) return std_logic_vector is
     variable xtime_8_v : std_logic_vector (07 downto 00) := ( B"0000_0000" );
     begin
        xtime_8_v := (  d(4)                            -- 7
                     & (d(3) xor d(7))                  -- 6
                     & (d(2) xor d(7) xor d(6))         -- 5
                     & (d(1) xor d(6) xor d(5))         -- 4
                     & (d(0) xor d(7) xor d(5))         -- 3
                     & (d(7) xor d(6))                  -- 2
                     & (d(6) xor d(5))                  -- 1
                     &  d(5));                          -- 0
     return xtime_8_v;
  end xtime_8;
 
end xtime_pkg;