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#include "stdafx.h"
#include "Random.h"
#include "System.h"
Random::Random()
{
// 4J - jave now uses the system nanosecond counter added to a "seedUniquifier" to get an initial seed. Our nanosecond timer is actually only millisecond accuate, so
// use QueryPerformanceCounter here instead
int64_t seed;
QueryPerformanceCounter((LARGE_INTEGER *)&seed);
seed += 8682522807148012LL;
setSeed(seed);
}
Random::Random(int64_t seed)
{
setSeed(seed);
}
void Random::setSeed(int64_t s)
{
this->seed = (s ^ 0x5DEECE66DLL) & ((1LL << 48) - 1);
haveNextNextGaussian = false;
}
int Random::next(int bits)
{
seed = (seed * 0x5DEECE66DLL + 0xBLL) & ((1LL << 48) - 1);
return (int)(seed >> (48 - bits));
}
void Random::nextBytes(byte *bytes, unsigned int count)
{
for(unsigned int i = 0; i < count; i++ )
{
bytes[i] = (byte)next(8);
}
}
double Random::nextDouble()
{
return (((int64_t)next(26) << 27) + next(27))
/ (double)(1LL << 53);
}
double Random::nextGaussian()
{
if (haveNextNextGaussian)
{
haveNextNextGaussian = false;
return nextNextGaussian;
}
else
{
double v1, v2, s;
do
{
v1 = 2 * nextDouble() - 1; // between -1.0 and 1.0
v2 = 2 * nextDouble() - 1; // between -1.0 and 1.0
s = v1 * v1 + v2 * v2;
} while (s >= 1 || s == 0);
double multiplier = sqrt(-2 * log(s)/s);
nextNextGaussian = v2 * multiplier;
haveNextNextGaussian = true;
return v1 * multiplier;
}
}
int Random::nextInt()
{
return next(32);
}
int Random::nextInt(int n)
{
assert (n>0);
if ((n & -n) == n) // i.e., n is a power of 2
return (int)(((int64_t)next(31) * n) >> 31); // 4J Stu - Made int64_t instead of long
int bits, val;
do
{
bits = next(31);
val = bits % n;
} while(bits - val + (n-1) < 0);
return val;
}
float Random::nextFloat()
{
return next(24) / ((float)(1 << 24));
}
int64_t Random::nextLong()
{
return ((int64_t)next(32) << 32) + next(32);
}
bool Random::nextBoolean()
{
return next(1) != 0;
}
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