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