//======================================================================
//
// sha512.v
// --------
// Top level wrapper for the SHA-512 hash function providing
// a simple memory like interface with 32 bit data access.
//
//
// Author: Joachim Strombergson
// Copyright (c) 2014, NORDUnet A/S
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// - Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
//
// - 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.
//
// - Neither the name of the NORDUnet nor the names of its contributors may
//   be used to endorse or promote products derived from this software
//   without specific prior written permission.
//
// 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
// HOLDER 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 sha512(
              // Clock and reset.
              input wire           clk,
              input wire           reset_n,

              // Control.
              input wire           cs,
              input wire           we,

              // Data ports.
              input wire  [7 : 0]  address,
              input wire  [31 : 0] write_data,
              output wire [31 : 0] read_data,
              output wire          error
             );

  //----------------------------------------------------------------
  // Internal constant and parameter definitions.
  //----------------------------------------------------------------
  parameter ADDR_NAME0           = 8'h00;
  parameter ADDR_NAME1           = 8'h01;
  parameter ADDR_VERSION         = 8'h02;

  parameter ADDR_CTRL            = 8'h08;
  parameter CTRL_INIT_BIT        = 0;
  parameter CTRL_NEXT_BIT        = 1;
  parameter CTRL_MODE_LOW_BIT    = 2;
  parameter CTRL_MODE_HIGH_BIT   = 3;
  parameter CTRL_WORK_FACTOR_BIT = 7;

  parameter ADDR_STATUS          = 8'h09;
  parameter STATUS_READY_BIT     = 0;
  parameter STATUS_VALID_BIT     = 1;

  parameter ADDR_WORK_FACTOR_NUM = 8'h0a;

  parameter ADDR_BLOCK0          = 8'h10;
  parameter ADDR_BLOCK1          = 8'h11;
  parameter ADDR_BLOCK2          = 8'h12;
  parameter ADDR_BLOCK3          = 8'h13;
  parameter ADDR_BLOCK4          = 8'h14;
  parameter ADDR_BLOCK5          = 8'h15;
  parameter ADDR_BLOCK6          = 8'h16;
  parameter ADDR_BLOCK7          = 8'h17;
  parameter ADDR_BLOCK8          = 8'h18;
  parameter ADDR_BLOCK9          = 8'h19;
  parameter ADDR_BLOCK10         = 8'h1a;
  parameter ADDR_BLOCK11         = 8'h1b;
  parameter ADDR_BLOCK12         = 8'h1c;
  parameter ADDR_BLOCK13         = 8'h1d;
  parameter ADDR_BLOCK14         = 8'h1e;
  parameter ADDR_BLOCK15         = 8'h1f;
  parameter ADDR_BLOCK16         = 8'h20;
  parameter ADDR_BLOCK17         = 8'h21;
  parameter ADDR_BLOCK18         = 8'h22;
  parameter ADDR_BLOCK19         = 8'h23;
  parameter ADDR_BLOCK20         = 8'h24;
  parameter ADDR_BLOCK21         = 8'h25;
  parameter ADDR_BLOCK22         = 8'h26;
  parameter ADDR_BLOCK23         = 8'h27;
  parameter ADDR_BLOCK24         = 8'h28;
  parameter ADDR_BLOCK25         = 8'h29;
  parameter ADDR_BLOCK26         = 8'h2a;
  parameter ADDR_BLOCK27         = 8'h2b;
  parameter ADDR_BLOCK28         = 8'h2c;
  parameter ADDR_BLOCK29         = 8'h2d;
  parameter ADDR_BLOCK30         = 8'h2e;
  parameter ADDR_BLOCK31         = 8'h2f;

  parameter ADDR_DIGEST0         = 8'h40;
  parameter ADDR_DIGEST1         = 8'h41;
  parameter ADDR_DIGEST2         = 8'h42;
  parameter ADDR_DIGEST3         = 8'h43;
  parameter ADDR_DIGEST4         = 8'h44;
  parameter ADDR_DIGEST5         = 8'h45;
  parameter ADDR_DIGEST6         = 8'h46;
  parameter ADDR_DIGEST7         = 8'h47;
  parameter ADDR_DIGEST8         = 8'h48;
  parameter ADDR_DIGEST9         = 8'h49;
  parameter ADDR_DIGEST10        = 8'h4a;
  parameter ADDR_DIGEST11        = 8'h4b;
  parameter ADDR_DIGEST12        = 8'h4c;
  parameter ADDR_DIGEST13        = 8'h4d;
  parameter ADDR_DIGEST14        = 8'h4e;
  parameter ADDR_DIGEST15        = 8'h4f;

  parameter CORE_NAME0         = 32'h73686132; // "sha2"
  parameter CORE_NAME1         = 32'h2d353132; // "-512"
  parameter CORE_VERSION       = 32'h302e3830; // "0.80"

  parameter MODE_SHA_512_224   = 2'h0;
  parameter MODE_SHA_512_256   = 2'h1;
  parameter MODE_SHA_384       = 2'h2;
  parameter MODE_SHA_512       = 2'h3;

  parameter DEFAULT_WORK_FACTOR_NUM = 32'h000f0000;


  //----------------------------------------------------------------
  // Registers including update variables and write enable.
  //----------------------------------------------------------------
  reg init_reg;
  reg init_new;
  reg init_we;
  reg init_set;

  reg next_reg;
  reg next_new;
  reg next_we;
  reg next_set;

  reg work_factor_reg;
  reg work_factor_new;
  reg work_factor_we;

  reg [1 : 0] mode_reg;
  reg [1 : 0] mode_new;
  reg         mode_we;

  reg [31 : 0] work_factor_num_reg;
  reg          work_factor_num_we;

  reg ready_reg;

  reg [31 : 0] block0_reg;
  reg          block0_we;
  reg [31 : 0] block1_reg;
  reg          block1_we;
  reg [31 : 0] block2_reg;
  reg          block2_we;
  reg [31 : 0] block3_reg;
  reg          block3_we;
  reg [31 : 0] block4_reg;
  reg          block4_we;
  reg [31 : 0] block5_reg;
  reg          block5_we;
  reg [31 : 0] block6_reg;
  reg          block6_we;
  reg [31 : 0] block7_reg;
  reg          block7_we;
  reg [31 : 0] block8_reg;
  reg          block8_we;
  reg [31 : 0] block9_reg;
  reg          block9_we;
  reg [31 : 0] block10_reg;
  reg          block10_we;
  reg [31 : 0] block11_reg;
  reg          block11_we;
  reg [31 : 0] block12_reg;
  reg          block12_we;
  reg [31 : 0] block13_reg;
  reg          block13_we;
  reg [31 : 0] block14_reg;
  reg          block14_we;
  reg [31 : 0] block15_reg;
  reg          block15_we;
  reg [31 : 0] block16_reg;
  reg          block16_we;
  reg [31 : 0] block17_reg;
  reg          block17_we;
  reg [31 : 0] block18_reg;
  reg          block18_we;
  reg [31 : 0] block19_reg;
  reg          block19_we;
  reg [31 : 0] block20_reg;
  reg          block20_we;
  reg [31 : 0] block21_reg;
  reg          block21_we;
  reg [31 : 0] block22_reg;
  reg          block22_we;
  reg [31 : 0] block23_reg;
  reg          block23_we;
  reg [31 : 0] block24_reg;
  reg          block24_we;
  reg [31 : 0] block25_reg;
  reg          block25_we;
  reg [31 : 0] block26_reg;
  reg          block26_we;
  reg [31 : 0] block27_reg;
  reg          block27_we;
  reg [31 : 0] block28_reg;
  reg          block28_we;
  reg [31 : 0] block29_reg;
  reg          block29_we;
  reg [31 : 0] block30_reg;
  reg          block30_we;
  reg [31 : 0] block31_reg;
  reg          block31_we;

  reg [511 : 0] digest_reg;
  reg           digest_valid_reg;


  //----------------------------------------------------------------
  // Wires.
  //----------------------------------------------------------------
  wire            core_init;
  wire            core_next;
  wire [1 : 0]    core_mode;
  wire            core_work_factor;
  wire [31 : 0]   core_work_factor_num;
  wire            core_ready;
  wire [1023 : 0] core_block;
  wire [511 : 0]  core_digest;
  wire            core_digest_valid;

  reg             state00_we;
  reg             state01_we;
  reg             state02_we;
  reg             state03_we;
  reg             state04_we;
  reg             state05_we;
  reg             state06_we;
  reg             state07_we;
  reg             state08_we;
  reg             state09_we;
  reg             state10_we;
  reg             state11_we;
  reg             state12_we;
  reg             state13_we;
  reg             state14_we;
  reg             state15_we;


  reg [31 : 0]    tmp_read_data;
  reg             tmp_error;


  //----------------------------------------------------------------
  // Concurrent connectivity for ports etc.
  //----------------------------------------------------------------
  assign core_init = init_reg;

  assign core_next = next_reg;

  assign core_mode = mode_reg;

  assign core_work_factor = work_factor_reg;
  assign core_work_factor_num = work_factor_num_reg;

  assign core_block = {block0_reg,  block1_reg,  block2_reg,  block3_reg,  block4_reg,
                       block5_reg,  block6_reg,  block7_reg,  block8_reg,  block9_reg,
                       block10_reg, block11_reg, block12_reg, block13_reg, block14_reg,
                       block15_reg, block16_reg, block17_reg, block18_reg, block19_reg,
                       block20_reg, block21_reg, block22_reg, block23_reg, block24_reg,
                       block25_reg, block26_reg, block27_reg, block28_reg, block29_reg,
                       block30_reg, block31_reg};

  assign read_data = tmp_read_data;
  assign error     = tmp_error;


  //----------------------------------------------------------------
  // core instantiation.
  //----------------------------------------------------------------
  sha512_core core(
                   .clk(clk),
                   .reset_n(reset_n),

                   .init(core_init),
                   .next(core_next),
                   .mode(core_mode),

                   .work_factor(core_work_factor),
                   .work_factor_num(core_work_factor_num),

                   .block(core_block),

                   .ready(core_ready),

                   .state_wr_data(write_data),
                   .state00_we(state00_we),
                   .state01_we(state01_we),
                   .state02_we(state02_we),
                   .state03_we(state03_we),
                   .state04_we(state04_we),
                   .state05_we(state05_we),
                   .state06_we(state06_we),
                   .state07_we(state07_we),
                   .state08_we(state08_we),
                   .state09_we(state09_we),
                   .state10_we(state10_we),
                   .state11_we(state11_we),
                   .state12_we(state12_we),
                   .state13_we(state13_we),
                   .state14_we(state14_we),
                   .state15_we(state15_we),

                   .digest(core_digest),
                   .digest_valid(core_digest_valid)
                  );


  //----------------------------------------------------------------
  // reg_update
  //
  // Update functionality for all registers in the core.
  // All registers are positive edge triggered with asynchronous
  // active low reset. All registers have write enable.
  //----------------------------------------------------------------
  always @ (posedge clk or negedge reset_n)
    begin
      if (!reset_n)
        begin
          init_reg            <= 1'h0;
          next_reg            <= 1'h0;
          mode_reg            <= MODE_SHA_512;
          work_factor_reg     <= 1'h0;
          work_factor_num_reg <= DEFAULT_WORK_FACTOR_NUM;
          ready_reg           <= 1'h0;
          digest_reg          <= 512'h0;
          digest_valid_reg    <= 1'h0;
          block0_reg          <= 32'h0;
          block1_reg          <= 32'h0;
          block2_reg          <= 32'h0;
          block3_reg          <= 32'h0;
          block4_reg          <= 32'h0;
          block5_reg          <= 32'h0;
          block6_reg          <= 32'h0;
          block7_reg          <= 32'h0;
          block8_reg          <= 32'h0;
          block9_reg          <= 32'h0;
          block10_reg         <= 32'h0;
          block11_reg         <= 32'h0;
          block12_reg         <= 32'h0;
          block13_reg         <= 32'h0;
          block14_reg         <= 32'h0;
          block15_reg         <= 32'h0;
          block16_reg         <= 32'h0;
          block17_reg         <= 32'h0;
          block18_reg         <= 32'h0;
          block19_reg         <= 32'h0;
          block20_reg         <= 32'h0;
          block21_reg         <= 32'h0;
          block22_reg         <= 32'h0;
          block23_reg         <= 32'h0;
          block24_reg         <= 32'h0;
          block25_reg         <= 32'h0;
          block26_reg         <= 32'h0;
          block27_reg         <= 32'h0;
          block28_reg         <= 32'h0;
          block29_reg         <= 32'h0;
          block30_reg         <= 32'h0;
          block31_reg         <= 32'h0;
        end
      else
        begin
          ready_reg        <= core_ready;
          digest_valid_reg <= core_digest_valid;

          if (init_we)
            begin
              init_reg <= init_new;
            end

          if (next_we)
            begin
              next_reg <= next_new;
            end

          if (mode_we)
            begin
              mode_reg <= mode_new;
            end

          if (work_factor_we)
            begin
              work_factor_reg <= work_factor_new;
            end

          if (work_factor_num_we)
            begin
              work_factor_num_reg <= write_data;
            end

          if (core_digest_valid)
            begin
              digest_reg <= core_digest;
            end

          if (block0_we)
            begin
              block0_reg <= write_data;
            end

          if (block1_we)
            begin
              block1_reg <= write_data;
            end

          if (block2_we)
            begin
              block2_reg <= write_data;
            end

          if (block3_we)
            begin
              block3_reg <= write_data;
            end

          if (block4_we)
            begin
              block4_reg <= write_data;
            end

          if (block5_we)
            begin
              block5_reg <= write_data;
            end

          if (block6_we)
            begin
              block6_reg <= write_data;
            end

          if (block7_we)
            begin
              block7_reg <= write_data;
            end

          if (block8_we)
            begin
              block8_reg <= write_data;
            end

          if (block9_we)
            begin
              block9_reg <= write_data;
            end

          if (block10_we)
            begin
              block10_reg <= write_data;
            end

          if (block11_we)
            begin
              block11_reg <= write_data;
            end

          if (block12_we)
            begin
              block12_reg <= write_data;
            end

          if (block13_we)
            begin
              block13_reg <= write_data;
            end

          if (block14_we)
            begin
              block14_reg <= write_data;
            end

          if (block15_we)
            begin
              block15_reg <= write_data;
            end

          if (block16_we)
            begin
              block16_reg <= write_data;
            end

          if (block17_we)
            begin
              block17_reg <= write_data;
            end

          if (block18_we)
            begin
              block18_reg <= write_data;
            end

          if (block19_we)
            begin
              block19_reg <= write_data;
            end

          if (block20_we)
            begin
              block20_reg <= write_data;
            end

          if (block21_we)
            begin
              block21_reg <= write_data;
            end

          if (block22_we)
            begin
              block22_reg <= write_data;
            end

          if (block23_we)
            begin
              block23_reg <= write_data;
            end

          if (block24_we)
            begin
              block24_reg <= write_data;
            end

          if (block25_we)
            begin
              block25_reg <= write_data;
            end

          if (block26_we)
            begin
              block26_reg <= write_data;
            end

          if (block27_we)
            begin
              block27_reg <= write_data;
            end

          if (block28_we)
            begin
              block28_reg <= write_data;
            end

          if (block29_we)
            begin
              block29_reg <= write_data;
            end

          if (block30_we)
            begin
              block30_reg <= write_data;
            end

          if (block31_we)
            begin
              block31_reg <= write_data;
            end
        end
    end // reg_update


  //----------------------------------------------------------------
  // flag_reset
  //
  // Logic to reset init and next flags that has been set.
  //----------------------------------------------------------------
  always @*
    begin : flag_reset
      init_new = 0;
      init_we  = 0;
      next_new = 0;
      next_we  = 0;

      if (init_set)
        begin
          init_new = 1;
          init_we  = 1;
        end
      else if (init_reg)
        begin
          init_new = 0;
          init_we  = 1;
        end

      if (next_set)
        begin
          next_new = 1;
          next_we  = 1;
        end
      else if (next_reg)
        begin
          next_new = 0;
          next_we  = 1;
        end
    end


  //----------------------------------------------------------------
  // api_logic
  //
  // Implementation of the api logic. If cs is enabled will either
  // try to write to or read from the internal registers.
  //----------------------------------------------------------------
  always @*
    begin : api_logic
      init_set           = 0;
      next_set           = 0;
      mode_new           = 2'b00;
      mode_we            = 0;
      work_factor_new    = 0;
      work_factor_we     = 0;
      work_factor_num_we = 0;
      block0_we          = 0;
      block1_we          = 0;
      block2_we          = 0;
      block3_we          = 0;
      block4_we          = 0;
      block5_we          = 0;
      block6_we          = 0;
      block7_we          = 0;
      block8_we          = 0;
      block9_we          = 0;
      block10_we         = 0;
      block11_we         = 0;
      block12_we         = 0;
      block13_we         = 0;
      block14_we         = 0;
      block15_we         = 0;
      block16_we         = 0;
      block17_we         = 0;
      block18_we         = 0;
      block19_we         = 0;
      block20_we         = 0;
      block21_we         = 0;
      block22_we         = 0;
      block23_we         = 0;
      block24_we         = 0;
      block25_we         = 0;
      block26_we         = 0;
      block27_we         = 0;
      block28_we         = 0;
      block29_we         = 0;
      block30_we         = 0;
      block31_we         = 0;
      state00_we         = 0;
      state01_we         = 0;
      state02_we         = 0;
      state03_we         = 0;
      state04_we         = 0;
      state05_we         = 0;
      state06_we         = 0;
      state07_we         = 0;
      state08_we         = 0;
      state09_we         = 0;
      state10_we         = 0;
      state11_we         = 0;
      state12_we         = 0;
      state13_we         = 0;
      state14_we         = 0;
      state15_we         = 0;
      tmp_read_data      = 32'h00000000;
      tmp_error          = 0;

      if (cs)
        begin
          if (we)
            begin
              case (address)
                // Write operations.
                ADDR_CTRL:
                  begin
                    init_set        = write_data[CTRL_INIT_BIT];
                    next_set        = write_data[CTRL_NEXT_BIT];
                    mode_new        = write_data[CTRL_MODE_HIGH_BIT : CTRL_MODE_LOW_BIT];
                    work_factor_new = write_data[CTRL_WORK_FACTOR_BIT];
                    work_factor_we  = 1;
                    mode_we         = 1;
                  end

                ADDR_WORK_FACTOR_NUM:
                  begin
                    work_factor_num_we = 1;
                  end

                ADDR_BLOCK0:
                  begin
                    block0_we = 1;
                   end

                ADDR_BLOCK1:
                  begin
                    block1_we = 1;
                  end

                ADDR_BLOCK2:
                  begin
                    block2_we = 1;
                  end

                ADDR_BLOCK3:
                  begin
                    block3_we = 1;
                  end

                ADDR_BLOCK4:
                  begin
                    block4_we = 1;
                  end

                ADDR_BLOCK5:
                  begin
                    block5_we = 1;
                  end

                ADDR_BLOCK6:
                  begin
                    block6_we = 1;
                  end

                ADDR_BLOCK7:
                  begin
                    block7_we = 1;
                  end

                ADDR_BLOCK8:
                  begin
                    block8_we = 1;
                  end

                ADDR_BLOCK9:
                  begin
                    block9_we = 1;
                  end

                ADDR_BLOCK10:
                  begin
                    block10_we = 1;
                  end

                ADDR_BLOCK11:
                  begin
                    block11_we = 1;
                  end

                ADDR_BLOCK12:
                  begin
                    block12_we = 1;
                  end

                ADDR_BLOCK13:
                  begin
                    block13_we = 1;
                  end

                ADDR_BLOCK14:
                  begin
                    block14_we = 1;
                  end

                ADDR_BLOCK15:
                  begin
                    block15_we = 1;
                  end

                ADDR_BLOCK16:
                  begin
                    block16_we = 1;
                  end

                ADDR_BLOCK17:
                  begin
                    block17_we = 1;
                  end

                ADDR_BLOCK18:
                  begin
                    block18_we = 1;
                  end

                ADDR_BLOCK19:
                  begin
                    block19_we = 1;
                  end

                ADDR_BLOCK20:
                  begin
                    block20_we = 1;
                  end

                ADDR_BLOCK21:
                  begin
                    block21_we = 1;
                  end

                ADDR_BLOCK22:
                  begin
                    block22_we = 1;
                  end

                ADDR_BLOCK23:
                  begin
                    block23_we = 1;
                  end

                ADDR_BLOCK24:
                  begin
                    block24_we = 1;
                  end

                ADDR_BLOCK25:
                  begin
                    block25_we = 1;
                  end

                ADDR_BLOCK26:
                  begin
                    block26_we = 1;
                  end

                ADDR_BLOCK27:
                  begin
                    block27_we = 1;
                  end

                ADDR_BLOCK28:
                  begin
                    block28_we = 1;
                  end

                ADDR_BLOCK29:
                  begin
                    block29_we = 1;
                  end

                ADDR_BLOCK30:
                  begin
                    block30_we = 1;
                  end

                ADDR_BLOCK31:
                  begin
                    block31_we = 1;
                  end

                ADDR_DIGEST0:
                  state00_we = 1;

                ADDR_DIGEST1:
                  state01_we = 1;

                ADDR_DIGEST2:
                  state02_we = 1;

                ADDR_DIGEST3:
                  state03_we = 1;

                ADDR_DIGEST4:
                  state04_we = 1;

                ADDR_DIGEST5:
                  state05_we = 1;

                ADDR_DIGEST6:
                  state06_we = 1;

                ADDR_DIGEST7:
                  state07_we = 1;

                ADDR_DIGEST8:
                  state08_we = 1;

                ADDR_DIGEST9:
                  state09_we = 1;

                ADDR_DIGEST10:
                  state10_we = 1;

                ADDR_DIGEST11:
                  state11_we = 1;

                ADDR_DIGEST12:
                  state12_we = 1;

                ADDR_DIGEST13:
                  state13_we = 1;

                ADDR_DIGEST14:
                  state14_we = 1;

                ADDR_DIGEST15:
                  state15_we = 1;

                default:
                  begin
                    tmp_error = 1;
                  end
              endcase // case (address)
            end // if (we)

          else
            begin
              case (address)
                // Read operations.
                ADDR_NAME0:
                  begin
                    tmp_read_data = CORE_NAME0;
                  end

                ADDR_NAME1:
                  begin
                    tmp_read_data = CORE_NAME1;
                  end

                ADDR_VERSION:
                  begin
                    tmp_read_data = CORE_VERSION;
                  end

                ADDR_CTRL:
                  begin
                    tmp_read_data = {24'h000000, work_factor_reg, 3'b000,
                                     mode_reg, next_reg, init_reg};
                  end

                ADDR_STATUS:
                  begin
                    tmp_read_data = {28'h0000000, 2'b00, digest_valid_reg, ready_reg};
                  end

                ADDR_WORK_FACTOR_NUM:
                  begin
                    tmp_read_data = work_factor_num_reg;
                  end

                ADDR_BLOCK0:
                  begin
                    tmp_read_data = block0_reg;
                  end

                ADDR_BLOCK1:
                  begin
                    tmp_read_data = block1_reg;
                  end

                ADDR_BLOCK2:
                  begin
                    tmp_read_data = block2_reg;
                  end

                ADDR_BLOCK3:
                  begin
                    tmp_read_data = block3_reg;
                  end

                ADDR_BLOCK4:
                  begin
                    tmp_read_data = block4_reg;
                  end

                ADDR_BLOCK5:
                  begin
                    tmp_read_data = block5_reg;
                  end

                ADDR_BLOCK6:
                  begin
                    tmp_read_data = block6_reg;
                  end

                ADDR_BLOCK7:
                  begin
                    tmp_read_data = block7_reg;
                  end

                ADDR_BLOCK8:
                  begin
                    tmp_read_data = block8_reg;
                  end

                ADDR_BLOCK9:
                  begin
                    tmp_read_data = block9_reg;
                  end

                ADDR_BLOCK10:
                  begin
                    tmp_read_data = block10_reg;
                  end

                ADDR_BLOCK11:
                  begin
                    tmp_read_data = block11_reg;
                  end

                ADDR_BLOCK12:
                  begin
                    tmp_read_data = block12_reg;
                  end

                ADDR_BLOCK13:
                  begin
                    tmp_read_data = block13_reg;
                  end

                ADDR_BLOCK14:
                  begin
                    tmp_read_data = block14_reg;
                  end

                ADDR_BLOCK15:
                  begin
                    tmp_read_data = block15_reg;
                  end

                ADDR_BLOCK16:
                  begin
                    tmp_read_data = block16_reg;
                  end

                ADDR_BLOCK17:
                  begin
                    tmp_read_data = block17_reg;
                  end

                ADDR_BLOCK18:
                  begin
                    tmp_read_data = block18_reg;
                  end

                ADDR_BLOCK19:
                  begin
                    tmp_read_data = block19_reg;
                  end

                ADDR_BLOCK20:
                  begin
                    tmp_read_data = block20_reg;
                  end

                ADDR_BLOCK21:
                  begin
                    tmp_read_data = block21_reg;
                  end

                ADDR_BLOCK22:
                  begin
                    tmp_read_data = block22_reg;
                  end

                ADDR_BLOCK23:
                  begin
                    tmp_read_data = block23_reg;
                  end

                ADDR_BLOCK24:
                  begin
                    tmp_read_data = block24_reg;
                  end

                ADDR_BLOCK25:
                  begin
                    tmp_read_data = block25_reg;
                  end

                ADDR_BLOCK26:
                  begin
                    tmp_read_data = block26_reg;
                  end

                ADDR_BLOCK27:
                  begin
                    tmp_read_data = block27_reg;
                  end

                ADDR_BLOCK28:
                  begin
                    tmp_read_data = block28_reg;
                  end

                ADDR_BLOCK29:
                  begin
                    tmp_read_data = block29_reg;
                  end

                ADDR_BLOCK30:
                  begin
                    tmp_read_data = block30_reg;
                  end

                ADDR_BLOCK31:
                  begin
                    tmp_read_data = block31_reg;
                  end

                ADDR_DIGEST0:
                  begin
                    tmp_read_data = digest_reg[511 : 480];
                  end

                ADDR_DIGEST1:
                  begin
                    tmp_read_data = digest_reg[479 : 448];
                  end

                ADDR_DIGEST2:
                  begin
                    tmp_read_data = digest_reg[447 : 416];
                  end

                ADDR_DIGEST3:
                  begin
                    tmp_read_data = digest_reg[415 : 384];
                  end

                ADDR_DIGEST4:
                  begin
                    tmp_read_data = digest_reg[383 : 352];
                  end

                ADDR_DIGEST5:
                  begin
                    tmp_read_data = digest_reg[351 : 320];
                  end

                ADDR_DIGEST6:
                  begin
                    tmp_read_data = digest_reg[319 : 288];
                  end

                ADDR_DIGEST7:
                  begin
                    tmp_read_data = digest_reg[287 : 256];
                  end

                ADDR_DIGEST8:
                  begin
                    tmp_read_data = digest_reg[255 : 224];
                  end

                ADDR_DIGEST9:
                  begin
                    tmp_read_data = digest_reg[223 : 192];
                  end

                ADDR_DIGEST10:
                  begin
                    tmp_read_data = digest_reg[191 : 160];
                  end

                ADDR_DIGEST11:
                  begin
                    tmp_read_data = digest_reg[159 : 128];
                  end

                ADDR_DIGEST12:
                  begin
                    tmp_read_data = digest_reg[127 :  96];
                  end

                ADDR_DIGEST13:
                  begin
                    tmp_read_data = digest_reg[95  :  64];
                  end

                ADDR_DIGEST14:
                  begin
                    tmp_read_data = digest_reg[63  :  32];
                  end

                ADDR_DIGEST15:
                  begin
                    tmp_read_data = digest_reg[31  :   0];
                  end

                default:
                  begin
                    tmp_error = 1;
                  end
              endcase // case (address)
            end
        end
    end // addr_decoder
endmodule // sha512

//======================================================================
// EOF sha512.v
//======================================================================