cvw/pipelined/src/fpu/resultsign.sv
2022-07-18 17:31:17 +00:00

63 lines
2.4 KiB
Systemverilog

///////////////////////////////////////////
//
// Written: me@KatherineParry.com
// Modified: 7/5/2022
//
// Purpose: calculating the result's sign
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// MIT LICENSE
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
// OR OTHER DEALINGS IN THE SOFTWARE.
////////////////////////////////////////////////////////////////////////////////////////////////
`include "wally-config.vh"
module resultsign(
input logic [2:0] Frm,
input logic FmaPs, FmaAs,
input logic ZInf,
input logic InfIn,
input logic FmaOp,
input logic [`NE+1:0] FmaSe,
input logic FmaSZero,
input logic Mult,
input logic R,
input logic S,
input logic Ms,
output logic Ws
);
logic Zeros;
logic Infs;
// Determine the sign if the sum is zero
// if cancelation then 0 unless round to -infinity
// if multiply then Psgn
// otherwise psign
assign Zeros = (FmaPs^FmaAs)&~(FmaSe[`NE+1] | ((FmaSe == 0) & (R|S)))&~Mult ? Frm[1:0] == 2'b10 : FmaPs;
// is the result negitive
// if p - z is the Sum negitive
// if -p + z is the Sum positive
// if -p - z then the Sum is negitive
assign Infs = ZInf ? FmaAs : FmaPs;
assign Ws = InfIn&FmaOp ? Infs : FmaSZero&FmaOp ? Zeros : Ms;
endmodule