aes_rcon.v

用于aes128加密的扩展密钥算法

/////////////////////////////////////////////////////////////////////
////                                                             ////
////  AES RCON Block                                             ////
////                                                             ////
////                                                             ////
////  Author: Rudolf Usselmann                                   ////
////          [e-mail]                                      ////
////                                                             ////
////                                                             ////
////  Downloaded from: http://www.opencores.org/cores/aes_core/  ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
////                                                             ////
//// Copyright (C) 2000-2002 Rudolf Usselmann                    ////
////                         www.asics.ws                        ////
////                         [e-mail]                       ////
////                                                             ////
//// 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 ``AS IS'' AND WITHOUT ANY     ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      ////
//// 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.                                 ////
////                                                             ////
/////////////////////////////////////////////////////////////////////

//  CVS Log
//
//  $Id: aes_rcon.v,v 1.1.1.1 2002/11/09 11:22:38 rudi Exp $
//
//  $Date: 2002/11/09 11:22:38 $
//  $Revision: 1.1.1.1 $
//  $Author: rudi $
//  $Locker:  $
//  $State: Exp $
//
// Change History:
//               $Log: aes_rcon.v,v $
//               Revision 1.1.1.1  2002/11/09 11:22:38  rudi
//               Initial Checkin
//
//
//
//
//
//

`include "timescale.v"

module aes_rcon(clk, kld, out);
input		clk;
input		kld;
output	[31:0]	out;
reg	[31:0]	out;
reg	[3:0]	rcnt;
wire	[3:0]	rcnt_next;

always @(posedge clk)
	if(kld)		out <= #1 32'h01_00_00_00;
	else		out <= #1 frcon(rcnt_next);

assign rcnt_next = rcnt + 4'h1;
always @(posedge clk)
	if(kld)		rcnt <= #1 4'h0;
	else		rcnt <= #1 rcnt_next;

function [31:0]	frcon;
input	[3:0]	i;
case(i)	// synopsys parallel_case
   4'h0: frcon=32'h01_00_00_00;
   4'h1: frcon=32'h02_00_00_00;
   4'h2: frcon=32'h04_00_00_00;
   4'h3: frcon=32'h08_00_00_00;
   4'h4: frcon=32'h10_00_00_00;
   4'h5: frcon=32'h20_00_00_00;
   4'h6: frcon=32'h40_00_00_00;
   4'h7: frcon=32'h80_00_00_00;
   4'h8: frcon=32'h1b_00_00_00;
   4'h9: frcon=32'h36_00_00_00;
   default: frcon=32'h00_00_00_00;
endcase
endfunction

endmodule