/////////////////////////////////////////////////////////////////////////                                                             ////////  SBOX                                                       ////////  The SBOX is essentially a 64x4 ROM                         ////////                                                             ////////  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  sbox4(addr, dout);input	[1:6] addr;output	[1:4] dout;reg	[1:4] dout;always @(addr) begin    case ({addr[1], addr[6], addr[2:5]})	//synopsys full_case parallel_case         0:  dout =  7;         1:  dout = 13;         2:  dout = 14;         3:  dout =  3;         4:  dout =  0;         5:  dout =  6;         6:  dout =  9;         7:  dout = 10;         8:  dout =  1;         9:  dout =  2;        10:  dout =  8;        11:  dout =  5;        12:  dout = 11;        13:  dout = 12;        14:  dout =  4;        15:  dout = 15;        16:  dout = 13;        17:  dout =  8;        18:  dout = 11;        19:  dout =  5;        20:  dout =  6;        21:  dout = 15;        22:  dout =  0;        23:  dout =  3;        24:  dout =  4;        25:  dout =  7;        26:  dout =  2;        27:  dout = 12;        28:  dout =  1;        29:  dout = 10;        30:  dout = 14;        31:  dout =  9;        32:  dout = 10;        33:  dout =  6;        34:  dout =  9;        35:  dout =  0;        36:  dout = 12;        37:  dout = 11;        38:  dout =  7;        39:  dout = 13;        40:  dout = 15;        41:  dout =  1;        42:  dout =  3;        43:  dout = 14;        44:  dout =  5;        45:  dout =  2;        46:  dout =  8;        47:  dout =  4;        48:  dout =  3;        49:  dout = 15;        50:  dout =  0;        51:  dout =  6;        52:  dout = 10;        53:  dout =  1;        54:  dout = 13;        55:  dout =  8;        56:  dout =  9;        57:  dout =  4;        58:  dout =  5;        59:  dout = 11;        60:  dout = 12;        61:  dout =  7;        62:  dout =  2;        63:  dout = 14;    endcase    endendmodule