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https://github.com/4jcraft/4jcraft.git
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114 lines
2.2 KiB
C++
114 lines
2.2 KiB
C++
#include "../Build/stdafx.h"
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#include "Random.h"
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#include <ctime>
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#include <cstdint> // for int64_t
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#include "../Build/System.h"
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Random::Random()
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{
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// 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
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// use QueryPerformanceCounter here instead
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__int64 seed;
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struct timespec ts;
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clock_gettime(CLOCK_MONOTONIC, &ts);
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seed = ts.tv_sec * 1000000000LL + ts.tv_nsec;
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seed += 8682522807148012LL;
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setSeed(seed);
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}
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Random::Random(__int64 seed)
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{
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setSeed(seed);
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}
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void Random::setSeed(__int64 s)
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{
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this->seed = (s ^ 0x5DEECE66DLL) & ((1LL << 48) - 1);
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haveNextNextGaussian = false;
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}
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int Random::next(int bits)
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{
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seed = (seed * 0x5DEECE66DLL + 0xBLL) & ((1LL << 48) - 1);
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return (int)(seed >> (48 - bits));
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}
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void Random::nextBytes(uint8_t *bytes, unsigned int count)
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{
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for(unsigned int i = 0; i < count; i++ )
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{
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bytes[i] = (uint8_t)next(8);
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}
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}
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double Random::nextDouble()
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{
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return (((__int64)next(26) << 27) + next(27))
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/ (double)(1LL << 53);
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}
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double Random::nextGaussian()
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{
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if (haveNextNextGaussian)
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{
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haveNextNextGaussian = false;
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return nextNextGaussian;
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}
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else
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{
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double v1, v2, s;
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do
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{
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v1 = 2 * nextDouble() - 1; // between -1.0 and 1.0
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v2 = 2 * nextDouble() - 1; // between -1.0 and 1.0
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s = v1 * v1 + v2 * v2;
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} while (s >= 1 || s == 0);
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double multiplier = sqrt(-2 * log(s)/s);
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nextNextGaussian = v2 * multiplier;
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haveNextNextGaussian = true;
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return v1 * multiplier;
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}
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}
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int Random::nextInt()
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{
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return next(32);
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}
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int Random::nextInt(int n)
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{
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assert (n>0);
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if ((n & -n) == n) // i.e., n is a power of 2
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return (int)(((__int64)next(31) * n) >> 31); // 4J Stu - Made __int64 instead of long
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int bits, val;
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do
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{
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bits = next(31);
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val = bits % n;
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} while(bits - val + (n-1) < 0);
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return val;
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}
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float Random::nextFloat()
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{
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return next(24) / ((float)(1 << 24));
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}
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__int64 Random::nextLong()
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{
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return ((__int64)next(32) << 32) + next(32);
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}
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bool Random::nextBoolean()
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{
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return next(1) != 0;
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}
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