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[/] [avs_aes/] [trunk/] [rtl/] [VHDL/] [shiftrow_fwd.vhd] - Diff between revs 10 and 11

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-- This file is part of the project  avs_aes
 
-- see: http://opencores.org/project,avs_aes
 
--
 
-- description: (Encryption implementation of Shiftrow) 
 
-- Shift Row rotates the Rows of the AES Block
 
-- This module takes the whole Rijdael state as input, extracts the rows,
 
-- shifts them and rebuilts the state.
 
--
 
-------------------------------------------------------------------------------
 
--
 
-- Author(s):
 
--         Thomas Ruschival -- ruschi@opencores.org (www.ruschival.de)
 
--
 
--------------------------------------------------------------------------------
 
-- Copyright (c) 2009, Authors and opencores.org
 
-- All rights reserved.
 
--
 
-- Redistribution and use in source and binary forms, with or without modification,
 
-- are permitted provided that the following conditions are met:
 
--    * Redistributions of source code must retain the above copyright notice,
 
--    this list of conditions and the following disclaimer.
 
--    * Redistributions in binary form must reproduce the above copyright notice,
 
--    this list of conditions and the following disclaimer in the documentation
 
--    and/or other materials provided with the distribution.
 
--    * Neither the name of the organization nor the names of its contributors
 
--    may be used to endorse or promote products derived from this software without
 
--    specific prior written permission.
 
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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
 
-------------------------------------------------------------------------------
 
-- version management:
 
-- $Author$
 
-- $Date$
 
-- $Revision$                   
 
-------------------------------------------------------------------------------
 
 
 
library IEEE;
 
use IEEE.numeric_std.all;
 
use IEEE.std_logic_1164.all;
 
 
 
library avs_aes_lib;
 
use avs_aes_lib.avs_aes_pkg.all;
 
 
 
 
 
architecture fwd of Shiftrow is
 
                -- type of converting the columns into rows
 
        subtype ROW is BYTEARRAY(0 to 3);
 
        -- Row signal for easier handling of the shift operations
 
        signal row1_in  : Row;                          -- 1st row
 
        signal row2_in  : Row;                          -- 2nd row
 
        signal row3_in  : Row;                          -- 3rd row
 
        signal row4_in  : Row;                          -- 4th row
 
        -- single rows after shift operation
 
        -- row1 of the shifted state = row1 of unshifted state 
 
        signal row2_out : Row;                          -- 2nd row
 
        signal row3_out : Row;                          -- 3rd row
 
        signal row4_out : Row;                          -- 4th row
 
 
 
begin  -- architecture arch1
 
        -- purpose: build the temorary internal signals for easier handling
 
        -- type   : combinational
 
        -- inputs : state_in
 
        -- outputs: state_out
 
        build_in : process (state_in) is
 
        begin  -- process build_in
 
                -- state is a DWORD array with 16, 24 or 32 Byte in 4,6 or 8 columns
 
                -- thus we loop through the columns and slice the column in its bytes
 
                for col_cnt in 0 to (state_in'high) loop
 
                        row1_in(col_cnt) <= state_in(col_cnt)(31 downto 24);
 
                        row2_in(col_cnt) <= state_in(col_cnt)(23 downto 16);
 
                        row3_in(col_cnt) <= state_in(col_cnt)(15 downto 8);
 
                        row4_in(col_cnt) <= state_in(col_cnt)(7 downto 0);
 
                end loop;  -- col_cnt
 
        end process build_in;
 
 
 
 
 
        -- purpose: shift rows of Rindael state by 'shift_delta'
 
        -- type   : combinational
 
        -- inputs : row(1 to 4)_in
 
        -- outputs: row(1 to 4)_out
 
        shifter : process (row2_in, row3_in, row4_in) is
 
        begin
 
                -- 1st row was never shifted so no reverse action needed
 
                -- rotate 2nd row left
 
                row2_out <= row2_in(row2_in'left+1 to row2_in'right) & row2_in(row2_in'left);
 
                --rotate by 2 left
 
                row3_out <= row3_in(row3_in'left+2 to row3_in'right) & row3_in(row3_in'left to row3_in'left+1);
 
                -- rotate by 3 left
 
                row4_out <= row4_in(row4_in'left+3 to row4_in'right) & row4_in(row4_in'left to row4_in'left+2);
 
        end process shifter;
 
 
 
 
 
        -- purpose: rebuilt the state form the shifted rows
 
        -- type   : combinational
 
        -- inputs : row1_out, row2_out, row3_out, row4_out
 
        -- outputs: state_out
 
        rebuilt_state : process (row1_in, row2_out, row3_out, row4_out) is
 
        begin  -- process rebuilt_state 
 
                for col_cnt in 0 to state_out'high loop   -- works because 15/4=3
 
                        state_out(col_cnt)(31 downto 24) <= row1_in(col_cnt);
 
                        state_out(col_cnt)(23 downto 16) <= row2_out(col_cnt);
 
                        state_out(col_cnt)(15 downto 8)  <= row3_out(col_cnt);
 
                        state_out(col_cnt)(7 downto 0)    <= row4_out(col_cnt);
 
                end loop;  -- col_cnt           
 
        end process rebuilt_state;
 
 
 
end architecture fwd;
 
 
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