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Core/Random: Refactor random number generation to use std::uniform_*_distribution to restrict result range instead of doing that ourselves

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* Seed SFMTRand with more values for its state

(cherry picked from commit 73bc3d8ea4)
This commit is contained in:
Shauren
2019-11-09 13:32:58 +01:00
parent 08b40733a5
commit b93bf95f2e
5 changed files with 36 additions and 72 deletions
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65
src/common/Utilities/SFMTRand.cpp
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@@ -16,67 +16,30 @@
*/
#include "SFMTRand.h"
#include <exception>
#include <algorithm>
#include <array>
#include <functional>
#include <random>
#include <emmintrin.h>
#include <ctime>
SFMTRand::SFMTRand()
{
RandomInit((uint32_t)(time(0)));
}
std::random_device dev;
if (dev.entropy() > 0)
{
std::array<uint32, SFMT_N32> seed;
std::generate(seed.begin(), seed.end(), std::ref(dev));
void SFMTRand::RandomInit(uint32_t seed) // Re-seed
{
sfmt_init_gen_rand(&state, seed);
}
int32_t SFMTRand::IRandom(int32_t min, int32_t max) // Output random integer
{
// Output random integer in the interval min <= x <= max
// Slightly inaccurate if (max-min+1) is not a power of 2
if (max <= min) {
if (max == min) return min; else return 0x80000000;
sfmt_init_by_array(&_state, seed.data(), seed.size());
}
// Assume 64 bit integers supported. Use multiply and shift method
uint32_t interval; // Length of interval
uint64_t longran; // Random bits * interval
uint32_t iran; // Longran / 2^32
interval = (uint32_t)(max - min + 1);
longran = (uint64_t)BRandom() * interval;
iran = (uint32_t)(longran >> 32);
// Convert back to signed and return result
return (int32_t)iran + min;
else
sfmt_init_gen_rand(&_state, uint32(time(nullptr)));
}
uint32_t SFMTRand::URandom(uint32_t min, uint32_t max)
uint32 SFMTRand::RandomUInt32() // Output random bits
{
// Output random integer in the interval min <= x <= max
// Slightly inaccurate if (max-min+1) is not a power of 2
if (max <= min) {
if (max == min) return min; else return 0;
}
// Assume 64 bit integers supported. Use multiply and shift method
uint32_t interval; // Length of interval
uint64_t longran; // Random bits * interval
uint32_t iran; // Longran / 2^32
interval = (uint32_t)(max - min + 1);
longran = (uint64_t)BRandom() * interval;
iran = (uint32_t)(longran >> 32);
// Convert back to signed and return result
return iran + min;
}
double SFMTRand::Random() // Output random floating point number
{
return sfmt_genrand_real1(&state);
}
uint32_t SFMTRand::BRandom() // Output random bits
{
return sfmt_genrand_uint32(&state);
return sfmt_genrand_uint32(&_state);
}
void* SFMTRand::operator new(size_t size, std::nothrow_t const&)