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`timescale 1ns / 1ps

// ============================================================================

//        __

//   \\__/ o\    (C) 2006-2019  Robert Finch, Waterloo

//    \  __ /    All rights reserved.

//     \/_//     robfinch<remove>@finitron.ca

//       ||

//

//

//

// This source file is free software: you can redistribute it and/or modify 

// it under the terms of the GNU Lesser General Public License as published 

// by the Free Software Foundation, either version 3 of the License, or     

// (at your option) any later version.                                      

//                                                                          

// This source file is distributed in the hope that it will be useful,      

// but WITHOUT ANY WARRANTY; without even the implied warranty of           

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            

// GNU General Public License for more details.                             

//                                                                          

// You should have received a copy of the GNU General Public License        

// along with this program.  If not, see <http://www.gnu.org/licenses/>.    

//                                                                          

// ============================================================================

module F32ToF80(a, o);

input [31:0] a;

output [79:0] o;

reg signo;

reg [14:0] expo;

reg [63:0] mano;

assign o = {signo,expo,mano};

wire signi;

wire [7:0] expi;

wire [22:0] mani;

wire xinf;      // exponent infinite

wire vz;        // value zero

wire xz;        // exponent zero

fpDecomp #(32) u1 (.i(a), .sgn(signi), .exp(expi), .man(mani), .xinf(xinf), .xz(xz), .vz(vz) );

wire [5:0] lz;

cntlz32 u2 ({mani,9'b111111111}, lz);   // '1' bit already unhidden due to denormalized number

always @*

begin

  // sign out always just = sign in

  signo <= signi;

  // special check for zero

  if (vz) begin

    expo <= 1'd0;

    mano <= 1'd0;

  end

  // convert infinity / nan

  // infinity in = infinity out

  else if (xinf) begin

    expo <= 15'h7fff;

    mano <= {mani,41'b0};

  end

  // convert denormal

  // a denormal was really a number with an exponent of -126

  // this value is easily represented in the double format

  // it may be possible to normalize the value if it isn't

  // zero

  else if (xz) begin

    expo <= 15'h3fff - 8'h7e - lz;      // 32767 "zero" -1022 - lz

    mano <= {mani << (lz + 1), 41'd0};  // shift one more to hide leading '1'

  end

  // convert typical number

  // adjust exponent, copy mantissa

  else begin

    expo <= expi + 15'h3fff - 8'h7f;

    mano <= {mani,41'd0};

  end

end

endmodule