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https://github.com/ultimatepp/ultimatepp.git
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147 lines
3 KiB
C++
147 lines
3 KiB
C++
#include "Core.h"
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namespace Upp {
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/* Written in 2018 by David Blackman and Sebastiano Vigna (vigna@acm.org)
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To the extent possible under law, the author has dedicated all copyright
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and related and neighboring rights to this software to the public domain
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worldwide. This software is distributed without any warranty.
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See <http://creativecommons.org/publicdomain/zero/1.0/>. */
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/* This is xoshiro256** 1.0, our all-purpose, rock-solid generator. It has
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excellent (sub-ns) speed, a state (256 bits) that is large enough for
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any parallel application, and it passes all tests we are aware of.
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For generating just floating-point numbers, xoshiro256+ is even faster.
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The state must be seeded so that it is not everywhere zero. If you have
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a 64-bit seed, we suggest to seed a splitmix64 generator and use its
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output to fill s. */
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static force_inline uint64_t s_rotl(const uint64_t x, int k) {
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return (x << k) | (x >> (64 - k)); // GCC/CLANG/MSC happily optimize this
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}
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force_inline
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static uint64 sNext(uint64 *s)
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{
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const uint64_t result_starstar = s_rotl(s[1] * 5, 7) * 9;
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const uint64_t t = s[1] << 17;
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s[2] ^= s[0];
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s[3] ^= s[1];
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s[1] ^= s[2];
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s[0] ^= s[3];
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s[2] ^= t;
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s[3] = s_rotl(s[3], 45);
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return result_starstar;
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}
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never_inline
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static void sSeed(uint64 *s)
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{
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#ifdef PLATFORM_POSIX
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int fd = open("/dev/urandom", O_RDONLY);
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if(fd != -1) {
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IGNORE_RESULT(
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read(fd, s, 4 * sizeof(uint64))
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);
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close(fd);
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}
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#else
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for(int pass = 0; pass < 4; pass++) {
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for(int i = 0; i < 4; i++) {
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CombineHash h;
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h << GetSysTime().Get() << usecs() << msecs();
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for(int p = 0; p < 2; p++) {
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Uuid uuid;
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CoCreateGuid((GUID *)&uuid); // GUID is basically a random number...
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h << uuid.v[0] << uuid.v[1];
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}
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s[i] ^= h;
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}
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}
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#endif
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}
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force_inline
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static uint64 *sState()
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{
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#ifdef MINGW_TLS_PATCH
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static FastMingwTls<uint64 *> s;
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#else
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thread_local uint64 *s;
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#endif
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if(!s) {
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thread_local uint64 state[4];
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s = state;
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sSeed(s);
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#ifdef PLATFORM_POSIX
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if(Thread::IsMain()) // non-main threads do not work with fork anyway
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pthread_atfork(NULL, NULL, [] { sSeed(s); }); // reseed random generator after fork
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#endif
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}
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return s;
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}
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dword Random()
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{
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return (dword)sNext(sState());
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}
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uint64 Random64()
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{
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return sNext(sState());
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}
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void Random64(uint64 *t, int n) {
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uint64 *s = sState();
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while(n-- > 0)
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*t++ = sNext(s);
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}
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dword Random(dword n) {
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ASSERT(n);
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uint64 *s = sState();
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dword mask = (1 << SignificantBits(n)) - 1;
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dword r;
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do
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r = (dword)sNext(s) & mask;
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while(r >= n);
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return r;
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}
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uint64 Random64(uint64 n) {
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ASSERT(n);
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uint64 *s = sState();
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uint64 mask = ((uint64)1 << SignificantBits64(n)) - 1;
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uint64 r;
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do
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r = sNext(s) & mask;
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while(r >= n);
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return r;
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}
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double Randomf()
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{
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return (sNext(sState()) >> 11) * (1. / (UINT64_C(1) << 53));
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}
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void SeedRandom()
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{
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sSeed(sState());
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}
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void SeedRandom(dword seed) {
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uint64 *s = sState();
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for(int i = 0; i < 4; i++)
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s[i] = 12345678 + seed + i; // xoshiro does not work well if all is zero
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}
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}
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