Use hardware timestamps in RNG seeding
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1 changed files with 15 additions and 7 deletions
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@ -16,6 +16,7 @@
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#include <stdlib.h>
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#include <limits>
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#include <chrono>
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#ifndef WIN32
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#include <sys/time.h>
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@ -43,15 +44,22 @@ static void RandFailure()
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static inline int64_t GetPerformanceCounter()
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{
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int64_t nCounter = 0;
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#ifdef WIN32
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QueryPerformanceCounter((LARGE_INTEGER*)&nCounter);
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// Read the hardware time stamp counter when available.
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// See https://en.wikipedia.org/wiki/Time_Stamp_Counter for more information.
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#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
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return __rdtsc();
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#elif !defined(_MSC_VER) && defined(__i386__)
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uint64_t r = 0;
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__asm__ volatile ("rdtsc" : "=A"(r)); // Constrain the r variable to the eax:edx pair.
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return r;
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#elif !defined(_MSC_VER) && (defined(__x86_64__) || defined(__amd64__))
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uint64_t r1 = 0, r2 = 0;
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__asm__ volatile ("rdtsc" : "=a"(r1), "=d"(r2)); // Constrain r1 to rax and r2 to rdx.
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return (r2 << 32) | r1;
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#else
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timeval t;
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gettimeofday(&t, NULL);
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nCounter = (int64_t)(t.tv_sec * 1000000 + t.tv_usec);
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// Fall back to using C++11 clock (usually microsecond or nanosecond precision)
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return std::chrono::high_resolution_clock::now().time_since_epoch().count();
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#endif
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return nCounter;
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}
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void RandAddSeed()
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