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// FastRandom.cpp
// Implements the cFastRandom class representing a fast random number generator
#include "Globals.h"
#include "FastRandom.h"
#include <random>
#ifdef _WIN32
#define thread_local static __declspec(thread)
#elif __APPLE__
#define thread_local static __thread
#endif
static unsigned int GetRandomSeed()
{
thread_local bool SeedCounterInitialized = 0;
thread_local unsigned int SeedCounter = 0;
if (!SeedCounterInitialized)
{
std::random_device rd;
std::uniform_int_distribution<unsigned int> dist;
SeedCounter = dist(rd);
SeedCounterInitialized = true;
}
return ++SeedCounter;
}
////////////////////////////////////////////////////////////////////////////////
// cFastRandom:
#if 0 && defined(_DEBUG)
// Self-test
// Both ints and floats are quick-tested to see if the random is calculated correctly, checking the range in ASSERTs,
// and if it performs well in terms of distribution (checked by avg, expected to be in the range midpoint
class cFastRandomTest
{
public:
cFastRandomTest(void)
{
TestInts();
TestFloats();
}
void TestInts(void)
{
printf("Testing ints...\n");
cFastRandom rnd;
int sum = 0;
const int BUCKETS = 8;
int Counts[BUCKETS];
memset(Counts, 0, sizeof(Counts));
const int ITER = 10000;
for (int i = 0; i < ITER; i++)
{
int v = rnd.NextInt(1000);
ASSERT(v >= 0);
ASSERT(v < 1000);
Counts[v % BUCKETS]++;
sum += v;
}
double avg = (double)sum / ITER;
printf("avg: %f\n", avg);
for (int i = 0; i < BUCKETS; i++)
{
printf(" bucket %d: %d\n", i, Counts[i]);
}
}
void TestFloats(void)
{
printf("Testing floats...\n");
cFastRandom rnd;
float sum = 0;
const int BUCKETS = 8;
int Counts[BUCKETS];
memset(Counts, 0, sizeof(Counts));
const int ITER = 10000;
for (int i = 0; i < ITER; i++)
{
float v = rnd.NextFloat(1000);
ASSERT(v >= 0);
ASSERT(v <= 1000);
Counts[((int)v) % BUCKETS]++;
sum += v;
}
sum = sum / ITER;
printf("avg: %f\n", sum);
for (int i = 0; i < BUCKETS; i++)
{
printf(" bucket %d: %d\n", i, Counts[i]);
}
}
} g_Test;
#endif
cFastRandom::cFastRandom(void) :
m_LinearRand(GetRandomSeed())
{
}
int cFastRandom::NextInt(int a_Range)
{
std::uniform_int_distribution<> distribution(0, a_Range - 1);
return distribution(m_LinearRand);
}
float cFastRandom::NextFloat(float a_Range)
{
std::uniform_real_distribution<float> distribution(0, a_Range);
return distribution(m_LinearRand);
}
int cFastRandom::GenerateRandomInteger(int a_Begin, int a_End)
{
std::uniform_int_distribution<> distribution(a_Begin, a_End);
return distribution(m_LinearRand);
}
////////////////////////////////////////////////////////////////////////////////
// MTRand:
MTRand::MTRand() :
m_MersenneRand(GetRandomSeed())
{
}
int MTRand::randInt(int a_Range)
{
std::uniform_int_distribution<> distribution(0, a_Range);
return distribution(m_MersenneRand);
}
int MTRand::randInt()
{
std::uniform_int_distribution<> distribution(0, std::numeric_limits<int>::max());
return distribution(m_MersenneRand);
}
double MTRand::rand(double a_Range)
{
std::uniform_real_distribution<> distribution(0, a_Range);
return distribution(m_MersenneRand);
}
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