cvw/src/fpu/fclassify.sv
2024-01-15 07:15:23 -08:00

68 lines
2.5 KiB
Systemverilog

///////////////////////////////////////////
// fclassivy.sv
//
// Written: me@KatherineParry.com
// Modified: 7/5/2022
//
// Purpose: Floating-point classify unit
//
// Documentation: RISC-V System on Chip Design Chapter 13
//
// A component of the CORE-V-WALLY configurable RISC-V project.
//
// Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
//
// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
//
// Licensed under the Solderpad Hardware License v 2.1 (the “License”); you may not use this file
// except in compliance with the License, or, at your option, the Apache License version 2.0. You
// may obtain a copy of the License at
//
// https://solderpad.org/licenses/SHL-2.1/
//
// Unless required by applicable law or agreed to in writing, any work distributed under the
// License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
// either express or implied. See the License for the specific language governing permissions
// and limitations under the License.
////////////////////////////////////////////////////////////////////////////////////////////////
module fclassify import cvw::*; #(parameter cvw_t P) (
input logic Xs, // sign bit
input logic XNaN, // is NaN
input logic XSNaN, // is signaling NaN
input logic XSubnorm, // is Subnormal
input logic XZero, // is zero
input logic XInf, // is infinity
output logic [P.XLEN-1:0] ClassRes // classify result
);
logic PInf, PZero, PNorm, PSubnorm; // is the input a positive infinity/zero/normal/subnormal
logic NInf, NZero, NNorm, NSubnorm; // is the input a negative infinity/zero/normal/subnormal
logic XNorm; // is the input normal
// determine the sub categories
assign XNorm= ~(XNaN | XInf| XSubnorm| XZero);
assign PInf = ~Xs&XInf;
assign NInf = Xs&XInf;
assign PNorm = ~Xs&XNorm;
assign NNorm = Xs&XNorm;
assign PSubnorm = ~Xs&XSubnorm;
assign NSubnorm = Xs&XSubnorm;
assign PZero = ~Xs&XZero;
assign NZero = Xs&XZero;
// determine sub category and combine into the result
// bit 0 - -Inf
// bit 1 - -Norm
// bit 2 - -Subnorm
// bit 3 - -Zero
// bit 4 - +Zero
// bit 5 - +Subnorm
// bit 6 - +Norm
// bit 7 - +Inf
// bit 8 - signaling NaN
// bit 9 - quiet NaN
assign ClassRes = {{P.XLEN-10{1'b0}}, XNaN&~XSNaN, XSNaN, PInf, PNorm, PSubnorm, PZero, NZero, NSubnorm, NNorm, NInf};
endmodule