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// Rand48.cpp
// this file is part of Context Free
// ---------------------
// Copyright (C) 2008 John Horigan - john@glyphic.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; either version 2
// of the License, or (at your option) any later version.
//
// 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.
//
// John Horigan can be contacted at john@glyphic.com or at
// John Horigan, 1209 Villa St., Mountain View, CA 94041-1123, USA
//
//
#include "Rand48.h"
#include <math.h>
#define RAND48_SEED_0 (0x330e)
#define RAND48_SEED_1 (0xabcd)
#define RAND48_SEED_2 (0x1234)
#define RAND48_MULT_0 (0xe66d)
#define RAND48_MULT_1 (0xdeec)
#define RAND48_MULT_2 (0x0005)
#define RAND48_MULT (0x0005deece66dLL)
#define RAND48_ADD (0x000b)
Rand48 Rand48::Common(RAND48_SEED_0, RAND48_SEED_1, RAND48_SEED_2);
bool Rand48::BigEndian = false;
double Rand48::getDouble(bool doBump)
{
if (doBump) bump();
#ifdef ULLONG_MAX
return ldexp((double) mSeed, -48);
#else
return ldexp((double) mSeed0, -48) +
ldexp((double) mSeed1, -32) +
ldexp((double) mSeed2, -16);
#endif
}
long Rand48::getLong(bool doBump)
{
if (doBump) bump();
#ifdef ULLONG_MAX
return (long) (mSeed >> 16);
#else
return ((long) mSeed2 << 16) + (long) mSeed1;
#endif
}
long Rand48::getPositive(bool doBump)
{
if (doBump) bump();
#ifdef ULLONG_MAX
return (long) (mSeed >> 17);
#else
return ((long) mSeed2 << 15) + ((long) mSeed1 >> 1);
#endif
}
unsigned long Rand48::getUnsigned(bool doBump)
{
if (doBump) bump();
#ifdef ULLONG_MAX
return (unsigned long) (mSeed >> 16);
#else
return ((unsigned long) mSeed2 << 16) + (unsigned long) mSeed1;
#endif
}
void Rand48::seed(unsigned short seed0, unsigned short seed1, unsigned short seed2)
{
#ifdef ULLONG_MAX
mSeed = (unsigned long long)seed0 |
((unsigned long long)seed1) << 16 |
((unsigned long long)seed2) << 32;
#else
mSeed0 = seed0; mSeed1 = seed1; mSeed2 = seed2;
#endif
}
void Rand48::seed(const unsigned short* seed)
{
#ifdef ULLONG_MAX
mSeed = (unsigned long long)seed[0] |
((unsigned long long)seed[1]) << 16 |
((unsigned long long)seed[2]) << 32;
#else
mSeed0 = seed[0]; mSeed1 = seed[1]; mSeed2 = seed[2];
#endif
}
void Rand48::setRand(long seed)
{
#ifdef ULLONG_MAX
mSeed = ((unsigned long long)RAND48_SEED_0 << 32) + (unsigned long long)seed;
#else
mSeed0 = RAND48_SEED_0;
mSeed1 = (unsigned short) seed;
mSeed2 = (unsigned short) (seed >> 16);
#endif
}
void Rand48::xorChar(char c, unsigned i)
{
if (BigEndian) i ^= 1;
#ifdef ULLONG_MAX
mSeed ^= ((unsigned long long)c) << (i * 8);
#else
unsigned offset = (i & 1) * 8;
switch (i) {
case 0:
case 1:
mSeed0 ^= ((unsigned short)c) << offset;
break;
case 2:
case 3:
mSeed1 ^= ((unsigned short)c) << offset;
break;
case 4:
case 5:
mSeed2 ^= ((unsigned short)c) << offset;
break;
}
#endif
}
void Rand48::bump()
{
#ifdef ULLONG_MAX
mSeed = (mSeed * RAND48_MULT + (unsigned long long) RAND48_ADD) & 0xffffffffffffLL;
#else
unsigned long accu;
unsigned short temp[2];
accu = (unsigned long) RAND48_MULT_0 * (unsigned long) mSeed0 +
(unsigned long) RAND48_ADD;
temp[0] = (unsigned short) accu; /* lower 16 bits */
accu >>= sizeof(unsigned short) * 8;
accu += (unsigned long) RAND48_MULT_0 * (unsigned long) mSeed1 +
(unsigned long) RAND48_MULT_1 * (unsigned long) mSeed0;
temp[1] = (unsigned short) accu; /* middle 16 bits */
accu >>= sizeof(unsigned short) * 8;
accu += RAND48_MULT_0 * mSeed2 + RAND48_MULT_1 * mSeed1 + RAND48_MULT_2 * mSeed0;
mSeed0 = temp[0];
mSeed1 = temp[1];
mSeed2 = (unsigned short) accu;
#endif
}
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