Subversion Repositories ft816float

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

//        __

//   \\__/ o\    (C) 2020-2022  Robert Finch, Waterloo

//    \  __ /    All rights reserved.

//     \/_//     robfinch@finitron.ca

//       ||

//

//      DFPCompare128.sv

//

// BSD 3-Clause License

// 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.

//

// 3. Neither the name of the copyright holder 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.

//

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

import DFPPkg::*;

module DFPCompare128(a, b, o);

input DFP128 a;

input DFP128 b;

output reg [11:0] o ='d0;

localparam N=34;                        // number of BCD digits

parameter TRUE = 1'b1;

parameter FALSE = 1'b0;

DFP128U au;

DFP128U bu;

DFPUnpack128 u00 (a, au);

DFPUnpack128 u01 (b, bu);

reg sa, sb;

always_comb

        sa = au.sign;

always_comb

        sb = bu.sign;

wire az = ~|{au.exp,au.sig};

wire bz = ~|{bu.exp,bu.sig};

wire unordered = au.nan | bu.nan;

wire eq = !unordered & ((az & bz) || (a==b));  // special test for zero

wire gt1 = {au.exp,au.sig} > {bu.exp,bu.sig};

wire lt1 = {au.exp,au.sig} < {bu.exp,bu.sig};

wire lt = sa ^ sb ? sa & !(az & bz): sa ? gt1 : lt1;

always_comb

begin

        o[0] = eq;

        o[1] = lt;

        o[2] = lt|eq;

        o[3] = lt1;

        o[4] = unordered;

        o[5] = ~eq;

        o[6] = ~lt;

        o[7] = ~(lt|eq);

        o[8] = ~lt1;

        o[9] = ~unordered;

        o[10] = 1'b0;

        o[11] = lt;

end

// an unorder comparison will signal a nan exception

//assign nanx = op!=`FCOR && op!=`FCUN && unordered;

endmodule