Browse Source

Use hardware timestamps in RNG seeding

pull/1/head
Pieter Wuille 5 years ago
parent
commit
f544094d5e
  1. 22
      src/random.cpp

22
src/random.cpp

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

Loading…
Cancel
Save