/usr/share/ada/adainclude/anet/anet-util.adb is in libanet0.1-dev 0.1-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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-- Copyright (C) 2011, 2012 secunet Security Networks AG
-- Copyright (C) 2011, 2012 Reto Buerki <reet@codelabs.ch>
-- Copyright (C) 2011, 2012 Adrian-Ken Rueegsegger <ken@codelabs.ch>
--
-- This program is free software; you can redistribute it and/or modify it
-- under the terms of the GNU General Public License as published by the
-- Free Software Foundation; either version 2 of the License, or (at your
-- option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
--
-- This program 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.
--
-- As a special exception, if other files instantiate generics from this
-- unit, or you link this unit with other files to produce an
-- executable this unit does not by itself cause the resulting
-- executable to be covered by the GNU General Public License. This
-- exception does not however invalidate any other reasons why the
-- executable file might be covered by the GNU Public License.
--
with Interfaces;
package body Anet.Util is
use Ada.Streams;
-------------------------------------------------------------------------
function Calculate_One_Complement
(Data : Ada.Streams.Stream_Element_Array)
return Double_Byte
is
function Make_Even
(Data : Stream_Element_Array)
return Stream_Element_Array;
-- Pad data array with a nil element if it has an uneven number of
-- elements.
function Make_Even
(Data : Stream_Element_Array)
return Stream_Element_Array
is
begin
if Data'Length mod 2 = 0 then
return Data;
end if;
return D : Stream_Element_Array (Data'First .. Data'Last + 1) do
D (Data'Range) := Data;
D (D'Last) := 0;
end return;
end Make_Even;
use Interfaces;
Sum : Unsigned_32 := 0;
Even : constant Stream_Element_Array := Make_Even (Data => Data);
Idx : Stream_Element_Offset := Even'First;
begin
loop
Sum := Sum + Unsigned_32 (Shift_Left
(Value => Unsigned_16 (Even (Idx)),
Amount => 8));
Sum := Sum + Unsigned_32 (Even (Idx + 1));
Idx := Idx + 2;
exit when Idx > Even'Last;
end loop;
loop
declare
Carries : constant Unsigned_32
:= Shift_Right (Value => Sum,
Amount => 16);
begin
exit when Carries < 1;
Sum := (Sum and 16#ffff#) + Carries;
end;
end loop;
Sum := (not Sum) mod 2 ** 16;
return Double_Byte (Sum);
end Calculate_One_Complement;
end Anet.Util;
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