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(*
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* Hedgewars, a worms-like game
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* Copyright (c) 2004, 2005 Andrey Korotaev <unC0Rr@gmail.com>
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*
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* Distributed under the terms of the BSD-modified licence:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* with the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*)
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unit uRandom;
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interface
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102
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procedure SetRandomSeed(Seed: shortstring);
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4
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function GetRandom: real; overload;
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function GetRandom(m: LongWord): LongWord; overload;
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implementation
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102
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var cirbuf: array[0..63] of Longword;
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n: byte;
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4
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102
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function GetNext: Longword;
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4
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begin
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102
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n:= (n + 1) and $3F;
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cirbuf[n]:=
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105
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(cirbuf[(n + 40) and $3F] + {n - 24 mod 64}
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cirbuf[(n + 9) and $3F]) {n - 55 mod 64}
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and $7FFFFFFF; {mod 2^31}
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102
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Result:= cirbuf[n]
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end;
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procedure SetRandomSeed(Seed: shortstring);
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var i: Longword;
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begin
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105
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if Length(Seed) > 60 then Seed:= copy(Seed, 1, 60); // not 64 to ensure we have even numbers in cirbuf
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102
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for i:= 0 to pred(Length(Seed)) do
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cirbuf[i]:= byte(Seed[i + 1]) * 35791253;
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for i:= Length(Seed) to 63 do
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cirbuf[i]:= i * 23860799;
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for i:= 0 to 1024 do GetNext;
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end;
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function GetRandom: real;
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begin
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102
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Result:= frac( GetNext * 0.0007301 + GetNext * 0.003019)
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end;
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102
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function GetRandom(m: LongWord): LongWord;
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begin
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105
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GetNext;
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102
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Result:= GetNext mod m
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end;
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end.
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