C4Random.cpp

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/*
 * OpenClonk, http://www.openclonk.org
 *
 * Copyright (c) 1998-2000, Matthes Bender
 * Copyright (c) 2001-2009, RedWolf Design GmbH, http://www.clonk.de/
 * Copyright (c) 2009-2016, The OpenClonk Team and contributors
 *
 * Distributed under the terms of the ISC license; see accompanying file
 * "COPYING" for details.
 *
 * "Clonk" is a registered trademark of Matthes Bender, used with permission.
 * See accompanying file "TRADEMARK" for details.
 *
 * To redistribute this file separately, substitute the full license texts
 * for the above references.
 */
 
/* Network-safe random number generator */
 
#include "C4Include.h"
#include "lib/C4Random.h"
 
#include <random>
 
#include <pcg/pcg_random.hpp>
 
int RandomCount = 0;
 
static pcg32 SeededRng()
{
    pcg_extras::seed_seq_from<std::random_device> seed_source;
    return pcg32(seed_source);
}
 
static pcg32 RandomRng, UnsyncedRandomRng = SeededRng();
 
void FixedRandom(uint64_t seed)
{
    RandomRng.seed(seed);
    RandomCount = 0;
}
 
uint32_t Random()
{
    uint32_t result = RandomRng();
    RecordRandom(UINT32_MAX, result);
    return result;
}
 
uint32_t Random(uint32_t iRange)
{
    if (!iRange) return 0u;
    uint32_t result = RandomRng(iRange);
    RecordRandom(iRange, result);
    return result;
}
 
uint32_t UnsyncedRandom()
{
    return UnsyncedRandomRng();
}
 
uint32_t UnsyncedRandom(uint32_t iRange)
{
    if (!iRange) return 0u;
    return UnsyncedRandomRng(iRange);
}
 
uint32_t SeededRandom(uint64_t iSeed, uint32_t iRange)
{
    if (!iRange) return 0;
    pcg32 rng(iSeed);
    return rng(iRange);
}