(*

 * Hedgewars, a worms-like game

 * Copyright (c) 2004, 2005 Andrey Korotaev <unC0Rr@gmail.com>

 *

 * Distributed under the terms of the BSD-modified licence:

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * with 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:

 *

 * 1. Redistributions of source code must retain the above copyright notice,

 *    this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright notice,

 *    this list of conditions and the following disclaimer in the documentation

 *    and/or other materials provided with the distribution.

 * 3. The name of the author may not be used to endorse or promote products

 *    derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED

 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO

 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;

 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *)

unit uRandom;

interface

uses uSHA;

procedure SetRandomParams(Seed: shortstring; FillBuf: shortstring);

function  GetRandom: real; overload;

function  GetRandom(m: LongWord): LongWord; overload;

implementation

var  sc1, sc2: TSHA1Context;

     Fill: shortstring;

procedure SetRandomParams(Seed: shortstring; FillBuf: shortstring);

begin

SHA1Init(sc1);

SHA1Update(sc1, @Seed, Length(Seed)+1);

Fill:= FillBuf

end;

function GetRandom: real;

var dig: TSHA1Digest;

begin

SHA1Update(sc1, @Fill[1], Length(Fill));

sc2:= sc1;

dig:= SHA1Final(sc1);

Result:= frac( dig.LongWords[0]*0.0000731563977

               + pi * dig.Words[6]

               + 0.0109070019*dig.Words[9]);

sc1:= sc2

end;

function  GetRandom(m: LongWord): LongWord;

var dig: TSHA1Digest;

begin

SHA1Update(sc1, @Fill[1], Length(Fill));

sc2:= sc1;

dig:= SHA1Final(sc1);

Result:= (((dig.LongWords[0] mod m) + (dig.LongWords[2] mod m)) mod m + (dig.LongWords[3] mod m)) mod m;

sc1:= sc2

end;

end.