cvw/pipelined/src/generic/lzc.sv

///////////////////////////////////////////
//
// Written: me@KatherineParry.com
// Modified: 7/5/2022
//
// Purpose: Leading Zero Counter
// 
// 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 lzc #(parameter WIDTH = 1) (
  input logic  [WIDTH-1:0]            num,    // number to count the leading zeroes of
  output logic [$clog2(WIDTH+1)-1:0]  ZeroCnt // the number of leading zeroes
);

  integer i;
  
  always_comb begin
    i = 0;
    while (~num[WIDTH-1-i] & (i < WIDTH)) i = i+1;  // search for leading one
    ZeroCnt = i[$clog2(WIDTH)-1:0];
  end
endmodule