//======================================================================
//
// sha512_h_constants.v
// ---------------------
// The H initial constants for the different modes in SHA-512.
//
//
// Author: Joachim Strombergson
// Copyright (c) 2014, SUNET
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or 
// without modification, are permitted provided that the following 
// conditions are met: 
// 
// 1. Redistributions of source code must retain the above copyright 
//    notice, this list of conditions and the following disclaimer. 
// 
// 2. 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. 
// 
// 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 OWNER 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, 
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
//======================================================================

module sha512_h_constants(
                          input wire  [1 : 0]  mode,

                          output wire [63 : 0] H0,
                          output wire [63 : 0] H1,
                          output wire [63 : 0] H2,
                          output wire [63 : 0] H3,
                          output wire [63 : 0] H4,
                          output wire [63 : 0] H5,
                          output wire [63 : 0] H6,
                          output wire [63 : 0] H7
                         );

  //----------------------------------------------------------------
  // Wires.
  //----------------------------------------------------------------
  reg [63 : 0] tmp_H0;
  reg [63 : 0] tmp_H1;
  reg [63 : 0] tmp_H2;
  reg [63 : 0] tmp_H3;
  reg [63 : 0] tmp_H4;
  reg [63 : 0] tmp_H5;
  reg [63 : 0] tmp_H6;
  reg [63 : 0] tmp_H7;


  //----------------------------------------------------------------
  // Concurrent connectivity for ports etc.
  //----------------------------------------------------------------
  assign H0 = tmp_H0;
  assign H1 = tmp_H1;
  assign H2 = tmp_H2;
  assign H3 = tmp_H3;
  assign H4 = tmp_H4;
  assign H5 = tmp_H5;
  assign H6 = tmp_H6;
  assign H7 = tmp_H7;

  
  //----------------------------------------------------------------
  // mode_mux
  //
  // Based on the given mode, the correct H constants are selected.
  //----------------------------------------------------------------
  always @*
    begin : mode_mux
      case(mode)
        0:
          begin
            // SHA-512/224
            tmp_H0 = 64'h8c3d37c819544da2;
            tmp_H1 = 64'h73e1996689dcd4d6;
            tmp_H2 = 64'h1dfab7ae32ff9c82;
            tmp_H3 = 64'h679dd514582f9fcf;
            tmp_H4 = 64'h0f6d2b697bd44da8;
            tmp_H5 = 64'h77e36f7304c48942;
            tmp_H6 = 64'h3f9d85a86a1d36c8;
            tmp_H7 = 64'h1112e6ad91d692a1;
          end

        1:
          begin
            // SHA-512/256
            tmp_H0 = 64'h22312194fc2bf72c; 
            tmp_H1 = 64'h9f555fa3c84c64c2; 
            tmp_H2 = 64'h2393b86b6f53b151; 
            tmp_H3 = 64'h963877195940eabd; 
            tmp_H4 = 64'h96283ee2a88effe3; 
            tmp_H5 = 64'hbe5e1e2553863992; 
            tmp_H6 = 64'h2b0199fc2c85b8aa; 
            tmp_H7 = 64'h0eb72ddc81c52ca2;
          end
        
        2:
          begin
            // SHA-384
            tmp_H0 = 64'hcbbb9d5dc1059ed8;
            tmp_H1 = 64'h629a292a367cd507;
            tmp_H2 = 64'h9159015a3070dd17; 
            tmp_H3 = 64'h152fecd8f70e5939; 
            tmp_H4 = 64'h67332667ffc00b31; 
            tmp_H5 = 64'h8eb44a8768581511; 
            tmp_H6 = 64'hdb0c2e0d64f98fa7; 
            tmp_H7 = 64'h47b5481dbefa4fa4;
          end
        
        3:
          begin
            // SHA-512
            tmp_H0 = 64'h6a09e667f3bcc908;
            tmp_H1 = 64'hbb67ae8584caa73b;
            tmp_H2 = 64'h3c6ef372fe94f82b; 
            tmp_H3 = 64'ha54ff53a5f1d36f1; 
            tmp_H4 = 64'h510e527fade682d1; 
            tmp_H5 = 64'h9b05688c2b3e6c1f; 
            tmp_H6 = 64'h1f83d9abfb41bd6b; 
            tmp_H7 = 64'h5be0cd19137e2179;  
          end
      endcase // case (addr)
    end // block: mode_mux
endmodule // sha512_h_constants

//======================================================================
// sha512_h_constants.v
//======================================================================