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Use cpuid intrinsics instead of asm code

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This commit is contained in:
Pieter Wuille 2017-07-13 16:43:05 -07:00
parent 7666250ffb
commit a9e82f6512
1 changed files with 6 additions and 11 deletions
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17
src/random.cpp
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@ -36,6 +36,10 @@
#include <mutex>
#if defined(__x86_64__) || defined(__amd64__) || defined(__i386__)
#include <cpuid.h>
#endif
#include <openssl/err.h>
#include <openssl/rand.h>
@ -72,17 +76,8 @@ static bool rdrand_supported = false;
static constexpr uint32_t CPUID_F1_ECX_RDRAND = 0x40000000;
static void RDRandInit()
{
uint32_t eax, ecx, edx;
#if defined(__i386__) && ( defined(__PIC__) || defined(__PIE__))
// Avoid clobbering ebx, as that is used for PIC on x86.
uint32_t tmp;
__asm__ ("mov %%ebx, %1; cpuid; mov %1, %%ebx": "=a"(eax), "=g"(tmp), "=c"(ecx), "=d"(edx) : "a"(1));
#else
uint32_t ebx;
__asm__ ("cpuid": "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx) : "a"(1));
#endif
//! When calling cpuid function #1, ecx register will have this set if RDRAND is available.
if (ecx & CPUID_F1_ECX_RDRAND) {
uint32_t eax, ebx, ecx, edx;
if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) && (ecx & CPUID_F1_ECX_RDRAND)) {
LogPrintf("Using RdRand as entropy source\n");
rdrand_supported = true;
}