+
−(*
+
− * Hedgewars, a free turn based strategy game
+
− * Copyright (c) 2004-2011 Andrey Korotaev <unC0Rr@gmail.com>
+
− *
+
− * 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; version 2 of the License
+
− *
+
− * 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.
+
− *
+
− * You should have received a copy of the GNU General Public License
+
− * along with this program; if not, write to the Free Software
+
− * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+
− *)
+
−
+
−{$INCLUDE "options.inc"}
+
−
+
−unit uRandom;
+
−(*
+
− * This unit supplies platform-independent functions for getting various
+
− * pseudo-random values based on a shared seed.
+
− *
+
− * This is necessary for accomplishing pseudo-random behavior in the game
+
− * without causing a desynchronisation of different clients when playing over
+
− * a network.
+
− *)
+
−interface
+
−uses uFloat;
+
−{$INCLUDE "config.inc"}
+
−
+
−procedure initModule;
+
−procedure freeModule;
+
−
+
−procedure SetRandomSeed(Seed: shortstring); // Sets the seed that should be used for generating pseudo-random values.
+
−function  GetRandom: hwFloat; overload; // Returns a pseudo-random hwFloat.
+
−function  GetRandom(m: LongWord): LongWord; overload; // Returns a positive pseudo-random integer smaller than m.
+
−function  rndSign(num: hwFloat): hwFloat; // Returns num with a random chance of having a inverted sign.
+
−
+
−implementation
+
−
+
−var cirbuf: array[0..63] of Longword;
+
−    n: byte;
+
−
+
−function GetNext: Longword;
+
−begin
+
−n:= (n + 1) and $3F;
+
−cirbuf[n]:=
+
−           (cirbuf[(n + 40) and $3F] +           {n - 24 mod 64}
+
−            cirbuf[(n +  9) and $3F])            {n - 55 mod 64}
+
−            and $7FFFFFFF;                       {mod 2^31}
+
−
+
−GetNext:= cirbuf[n]
+
−end;
+
−
+
−procedure SetRandomSeed(Seed: shortstring);
+
−var i: Longword;
+
−begin
+
−n:= 54;
+
−
+
−if Length(Seed) > 54 then Seed:= copy(Seed, 1, 54); // not 55 to ensure we have odd numbers in cirbuf
+
−
+
−for i:= 0 to Pred(Length(Seed)) do
+
−    cirbuf[i]:= byte(Seed[i + 1]);
+
−
+
−for i:= Length(Seed) to 54 do
+
−    cirbuf[i]:= $A98765 + 68; // odd number
+
−
+
−for i:= 0 to 1023 do GetNext
+
−end;
+
−
+
−function GetRandom: hwFloat;
+
−begin
+
−GetNext;
+
−GetRandom.isNegative:= false;
+
−GetRandom.QWordValue:= GetNext
+
−end;
+
−
+
−function GetRandom(m: LongWord): LongWord;
+
−begin
+
−GetNext;
+
−GetRandom:= GetNext mod m
+
−end;
+
−
+
−function rndSign(num: hwFloat): hwFloat;
+
−begin
+
−num.isNegative:= odd(GetNext);
+
−rndSign:= num
+
−end;
+
−
+
−procedure initModule;
+
−begin
+
−    n:= 54;
+
−    FillChar(cirbuf, 64*sizeof(Longword), 0);
+
−end;
+
−
+
−procedure freeModule;
+
−begin
+
−
+
−end;
+
−
+
−end.