/////////////////////////////////////////////////////////////////////////                                                             ////////  DES                                                        ////////  DES Top Level module                                       ////////                                                             ////////  Author: Rudolf Usselmann                                   ////////          russelmann@hotmail.com                             ////////                                                             /////////////////////////////////////////////////////////////////////////////                                                             //////// Copyright (C) 2000 Rudolf Usselmann                         ////////                    russelmann@hotmail.com                   ////////                                                             //////// 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.                                 ////////                                                             /////////////////////////////////////////////////////////////////////////module des(desOut, desIn, key, roundSel, clk);output	[63:0]	desOut;input	[63:0]	desIn;input	[55:0]	key;input	[3:0]	roundSel;input		clk;wire	[1:48]	K_sub;wire	[1:64]	IP, FP;reg	[1:32]	L, R;wire	[1:32]	Xin;wire	[1:32]	Lout, Rout;wire	[1:32]	out;assign Lout = (roundSel == 0) ? IP[33:64] : R;assign Xin  = (roundSel == 0) ? IP[01:32] : L;assign Rout = Xin ^ out;assign FP = { Rout, Lout};crp u0( .P(out), .R(Lout), .K_sub(K_sub) );always @(posedge clk)        L <= #1 Lout;always @(posedge clk)        R <= #1 Rout;        // Select a subkey from key.key_sel u1(K_sub, key, roundSel);// Perform initial permutationassign IP[1:64] = {	desIn[06], desIn[14], desIn[22], desIn[30], desIn[38], desIn[46],			desIn[54], desIn[62], desIn[04], desIn[12], desIn[20], desIn[28],			desIn[36], desIn[44], desIn[52], desIn[60], desIn[02], desIn[10], 			desIn[18], desIn[26], desIn[34], desIn[42], desIn[50], desIn[58], 			desIn[00], desIn[08], desIn[16], desIn[24], desIn[32], desIn[40], 			desIn[48], desIn[56], desIn[07], desIn[15], desIn[23], desIn[31], 			desIn[39], desIn[47], desIn[55], desIn[63], desIn[05], desIn[13],			desIn[21], desIn[29], desIn[37], desIn[45], desIn[53], desIn[61],			desIn[03], desIn[11], desIn[19], desIn[27], desIn[35], desIn[43],			desIn[51], desIn[59], desIn[01], desIn[09], desIn[17], desIn[25],			desIn[33], desIn[41], desIn[49], desIn[57] };// Perform final permutationassign desOut = {	FP[40], FP[08], FP[48], FP[16], FP[56], FP[24], FP[64], FP[32], 			FP[39], FP[07], FP[47], FP[15], FP[55], FP[23], FP[63], FP[31], 			FP[38], FP[06], FP[46], FP[14], FP[54], FP[22], FP[62], FP[30], 			FP[37], FP[05], FP[45], FP[13], FP[53], FP[21], FP[61], FP[29], 			FP[36], FP[04], FP[44], FP[12], FP[52], FP[20], FP[60], FP[28], 			FP[35], FP[03], FP[43], FP[11], FP[51], FP[19], FP[59], FP[27],			FP[34], FP[02], FP[42], FP[10], FP[50], FP[18], FP[58], FP[26], 			FP[33], FP[01], FP[41], FP[09], FP[49], FP[17], FP[57], FP[25] };endmodule