1 (*

     2  * Hedgewars, a worms-like game

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

     4  *

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

     6  *

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

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

     9  * with the Software without restriction, including without limitation the

    10  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

    11  * sell copies of the Software, and to permit persons to whom the Software is

    12  * furnished to do so, subject to the following conditions:

    13  *

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

    15  *    this list of conditions and the following disclaimer.

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

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

    18  *    and/or other materials provided with the distribution.

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

    20  *    derived from this software without specific prior written permission.

    21  *

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

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

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

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

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

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

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

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

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

    31  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    32  *)

    33 

    34 unit uRandom;

    35 interface

    36 uses uSHA;

    37 

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

    39 function  GetRandom: real; overload;

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

    41 

    42 implementation

    43 var  sc1, sc2: TSHA1Context;

    44      Fill: shortstring;

    45 

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

    47 begin

    48 SHA1Init(sc1);

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

    50 Fill:= FillBuf

    51 end;

    52 

    53 function GetRandom: real;

    54 var dig: TSHA1Digest;

    55 begin

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

    57 sc2:= sc1;

    58 dig:= SHA1Final(sc1);

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

    60                + pi * dig.Words[6]

    61                + 0.0109070019*dig.Words[9]);

    62 sc1:= sc2

    63 end;

    64 

    65 function  GetRandom(m: LongWord): LongWord;

    66 var dig: TSHA1Digest;

    67 begin

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

    69 sc2:= sc1;

    70 dig:= SHA1Final(sc1);

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

    72 sc1:= sc2

    73 end;

    74 

    75 end.