-------------------------------------------------------------------------------
-- Title      : Shift Rows using std_logic_vector
-- Project    : LGC
-------------------------------------------------------------------------------
-- File       : shiftrows.vhd
-- Author     : Frank K. Gurkaynak  <kgf@antalya.ee.ethz.ch>
-- Company    : Integrated Systems Laboratory, ETH Zurich
-- Created    : 2004-11-15
-- Last update: 2004-12-05
-- Platform   : ModelSim (simulation), Synopsys (synthesis)
-- Standard   : VHDL'87
-------------------------------------------------------------------------------
-- Description: This should be ungrouped it is just a 1:1 assignmnet of
--              the shiftrows function.
-------------------------------------------------------------------------------
-- Copyright (c) 2004 Integrated Systems Laboratory, ETH Zurich
-------------------------------------------------------------------------------
-- Revisions  :
-- CVS ID     : $Id: shiftrows.vhd,v 1.1 2004/12/05 16:35:48 kgf Exp $
-- Date        Version  Author  Description
-- 2004-11-15  1.0      kgf	Created
-------------------------------------------------------------------------------

library IEEE;
use IEEE.std_logic_1164.all;

entity ishiftrows is
  port(
    InxDI   : in  std_logic_vector (127 downto 0);
    OutxDO  : out std_logic_vector (127 downto 0)
  );
end ishiftrows;

architecture permutation of ishiftrows is

  type BytesType is array (0 to 15) of std_logic_vector (7 downto 0);
  signal InBxD, OutBxD : BytesType;
  
begin

-- hmm earlier version had fucked up the ordering of the bytes..
-- So when you have a 128 bit data Byte 0 is 127..120 
  
  gen_byte_assign: for i in 0 to 15 generate
                     InBxD(i) <= InxDI(((15-i)*8)+7 downto (15-i)*8);
                     OutxDO(((15-i)*8)+7 downto (15-i)*8) <= OutBxD(i);
                   end generate gen_byte_assign;


-- Row 0   as it is 
  OutBxD(0) <= InBxD( 0); OutBxD(4) <= InBxD( 4); OutBxD( 8) <= InBxD( 8); OutBxD(12) <= InBxD(12); 
-- Row 1   one left
  OutBxD(1) <=  InBxD(13); 
  OutBxD(5) <=   InBxD( 1); 
  OutBxD( 9) <=  InBxD( 5); 
  OutBxD(13) <=  InBxD( 9); 
-- Row 2   two left
  OutBxD(2) <= InBxD(10); OutBxD(6) <= InBxD(14); OutBxD(10) <= InBxD( 2); OutBxD(14) <= InBxD( 6); 
-- Row 3   three left
  OutBxD(3) <=  InBxD(7); 
  OutBxD(7) <=  InBxD(11);
  OutBxD(11) <=  InBxD(15); 
  OutBxD(15) <=  InBxD(3); 


                     
  
end permutation;