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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT RUN-TIME COMPONENTS --
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4 -- --
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5 -- S Y S T E M . R A N D O M _ S E E D --
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6 -- --
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7 -- B o d y --
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8 -- --
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9 -- Copyright (C) 2011-2017, Free Software Foundation, Inc. --
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- Version used on all systems except Ravenscar where Calendar is unavailable
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33
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34 with Ada.Calendar; use Ada.Calendar;
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35 with Ada.Unchecked_Conversion;
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36
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37 package body System.Random_Seed is
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38
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39 Y2K : constant Time :=
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40 Time_Of (Year => 2000, Month => 1, Day => 1, Seconds => 0.0);
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41 -- First day of Year 2000, to get a duration
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42
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43 function To_U64 is
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44 new Ada.Unchecked_Conversion (Duration, Interfaces.Unsigned_64);
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45
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46 --------------
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47 -- Get_Seed --
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48 --------------
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49
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50 function Get_Seed return Interfaces.Unsigned_64 is
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51 begin
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52 return To_U64 (Clock - Y2K);
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53 end Get_Seed;
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54
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55 end System.Random_Seed;
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