cvw/pipelined/src/generic/lzc.sv

///////////////////////////////////////////
//
// Written: me@KatherineParry.com
// Modified: 7/5/2022
//
// Purpose: Leading Zero Counter
// 
// 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.
////////////////////////////////////////////////////////////////////////////////////////////////
//leading zero counter i.e. priority encoder
module lzc #(parameter WIDTH = 1) (
    input logic  [WIDTH-1:0]            num,
    output logic [$clog2(WIDTH+1)-1:0]  ZeroCnt
);
/* verilator lint_off CMPCONST */
/* verilator lint_off WIDTH */
    
    int i;
    always_comb begin
        i = 0;
        while (~num[WIDTH-1-i] & (i < WIDTH)) i = i+1;  // search for leading one
        ZeroCnt = i;
    end
/* verilator lint_on WIDTH */
/* verilator lint_on CMPCONST */
endmodule