Subversion Repositories thor

/* ============================================================================

        (C) 2006, 2007  Robert T Finch

        All rights reserved.

        rob@birdcomputer.ca

        fp_decomp.v

                - decompose floating point value

                - parameterized width

        Verilog 1995

        This source code is free for use and modification for non-commercial or

        evaluation purposes, provided this copyright statement and disclaimer

        remains present in the file.

        If the code is modified, please state the origin and note that the code

        has been modified.

        NO WARRANTY.

        THIS Work, IS PROVIDEDED "AS IS" WITH NO WARRANTIES OF ANY KIND, WHETHER

        EXPRESS OR IMPLIED. The user must assume the entire risk of using the

        Work.

        IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY

        INCIDENTAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES WHATSOEVER RELATING TO

        THE USE OF THIS WORK, OR YOUR RELATIONSHIP WITH THE AUTHOR.

        IN ADDITION, IN NO EVENT DOES THE AUTHOR AUTHORIZE YOU TO USE THE WORK

        IN APPLICATIONS OR SYSTEMS WHERE THE WORK'S FAILURE TO PERFORM CAN

        REASONABLY BE EXPECTED TO RESULT IN A SIGNIFICANT PHYSICAL INJURY, OR IN

        LOSS OF LIFE. ANY SUCH USE BY YOU IS ENTIRELY AT YOUR OWN RISK, AND YOU

        AGREE TO HOLD THE AUTHOR AND CONTRIBUTORS HARMLESS FROM ANY CLAIMS OR

        LOSSES RELATING TO SUCH UNAUTHORIZED USE.

        Ref: Webpack 8.1i Spartan3-4 xc3s1000 4ft256

        10 slices / 20 LUTs / 12 ns  (32 bits)

============================================================================ */

module fp_decomp(i, sgn, exp, man, fract, xz, mz, vz, inf, xinf, qnan, snan, nan);

parameter WID=32;

localparam MSB  = WID-1;

localparam EMSB = WID==80 ? 14 :

                  WID==64 ? 10 :

                                  WID==52 ? 10 :

                                  WID==48 ? 10 :

                                  WID==44 ? 10 :

                                  WID==42 ? 10 :

                                  WID==40 ?  9 :

                                  WID==32 ?  7 :

                                  WID==24 ?  6 : 4;

localparam FMSB = WID==80 ? 63 :

                  WID==64 ? 51 :

                                  WID==52 ? 39 :

                                  WID==48 ? 35 :

                                  WID==44 ? 31 :

                                  WID==42 ? 29 :

                                  WID==40 ? 28 :

                                  WID==32 ? 22 :

                                  WID==24 ? 15 : 9;

input [MSB:0] i;

output sgn;

output [EMSB:0] exp;

output [FMSB:0] man;

output [FMSB+1:0] fract; // mantissa with hidden bit recovered

output xz;              // denormalized - exponent is zero

output mz;              // mantissa is zero

output vz;              // value is zero (both exponent and mantissa are zero)

output inf;             // all ones exponent, zero mantissa

output xinf;    // all ones exponent

output qnan;    // nan

output snan;    // signalling nan

output nan;

// Decompose input

assign sgn = i[MSB];

assign exp = i[MSB-1:FMSB+1];

assign man = i[FMSB:0];

assign xz = !(|exp);    // denormalized - exponent is zero

assign mz = !(|man);    // mantissa is zero

assign vz = xz & mz;    // value is zero (both exponent and mantissa are zero)

assign inf = &exp & mz; // all ones exponent, zero mantissa

assign xinf = &exp;

assign qnan = &exp &  man[FMSB];

assign snan = &exp & !man[FMSB] & !mz;

assign nan = &exp & !mz;

assign fract = {!xz,i[FMSB:0]};

endmodule