raze/source/exhumed/src/random.cpp

83 lines
2.1 KiB
C++

//-------------------------------------------------------------------------
/*
Copyright (C) 2010-2019 EDuke32 developers and contributors
Copyright (C) 2019 sirlemonhead, Nuke.YKT
This file is part of PCExhumed.
PCExhumed is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License version 2
as published by the Free Software Foundation.
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
//-------------------------------------------------------------------------
#include "ns.h"
#include "random.h"
BEGIN_PS_NS
int randA = 0;
int randB = 0x11111111;
int randC = 0x1010101;
void InitRandom()
{
randA = 0;
randB = 0x11111111;
randC = 0x1010101;
}
// TODO - checkme
int RandomBit()
{
randA = (randA >> 1) | (((randA ^ ((randA >> 1) ^ (randA >> 2) ^ (randA >> 31) ^ (randA >> 6) ^ (randA >> 4))) & 1) << 31);
randB = (randB >> 1) | ((((randB >> 2) ^ (randB >> 30)) & 1) << 30);
randC = (randC >> 1) | ((((randC >> 1) ^ (randC >> 28)) & 1) << 28);
return ((randA == 0) & randC | (randB & randA)) & 1;
}
char RandomByte()
{
char randByte = RandomBit() << 7;
randByte |= RandomBit() << 6;
randByte |= RandomBit() << 5;
randByte |= RandomBit() << 4;
randByte |= RandomBit() << 3;
randByte |= RandomBit() << 2;
randByte |= RandomBit() << 1;
randByte |= RandomBit();
return randByte;
}
short RandomWord()
{
short randWord = RandomByte() << 8;
randWord |= RandomByte();
return randWord;
}
int RandomLong()
{
int randLong = RandomWord() << 16;
randLong |= RandomWord();
return randLong;
}
int RandomSize(int nSize)
{
int randSize = 0;
while (nSize > 0)
{
randSize = randSize * 2 | RandomBit();
nSize--;
}
return randSize;
}
END_PS_NS