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

//        __

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

//    \  __ /    All rights reserved.

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

//       ||

//

//      positToFp.sv

//    - posit number to floating point convertor

//    - can issue every clock cycle

//    - parameterized width

//    - IEEE 754 representation

//

// Parts of this code originated from Posit_to_FP.v by Manish Kumar Jaiswal

//

// 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 .

//

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

import posit::*;

import fp::*;

`include "../fpu/fpTypes.sv"

module positToFp(i, o);

input [FPWID-1:0] i;

output reg [FPWID-1:0] o;

parameter BIAS = {1'b0,{EMSB{1'b1}}};

localparam N = FPWID;

localparam E = EMSB+1;

localparam M = FMSB+1;

localparam Bs = $clog2(FPWID-1);

localparam EO = E > es+Bs ? E : es+Bs;

wire sgn;

wire rgs;

wire [Bs-1:0] rgm;

wire [es-1:0] exp;

wire [N-es-1:0] sig;

wire zer;

wire inf;

positDecompose #(.PSTWID(PSTWID)) u1 (.i(i), .sgn(sgn), .rgs(rgs), .rgm(rgm), .exp(exp), .sig(sig), .zer(zer), .inf(inf));

wire [N-1:0] m = {sig,{es{1'b0}}};

wire [EO+1:0] e;

assign e = {(rgs ? {{EO-es-Bs+1{1'b0}},rgm} : -{{EO-es-Bs+1{1'b0}},rgm}),exp} + BIAS;

wire exv = |e[EO:E];

wire exinf = &e[E-1:0];

always @*

casez({zer,inf|exv|exinf})    // exponent all ones or exponent overflow?

// convert to +0.0 zero-in zero-out (the sign will always be plus)

2'b1?:  o = {sgn,{FPWID-1{1'b0}}};

// Infinity in or exponent overflow in conversion = infinity out

2'b01:  o = {sgn,{E-1{1'b1}},{M{1'b0}}};

// Other numbers

default:  o = {sgn,e[E-1:0],m[N-2:E]};

endcase

endmodule