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// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include <thread>
#ifdef _MSC_VER
#include <intrin.h>
#endif
#include "common/x64/cpu_detect.h"
#include "common/x64/cpu_wait.h"
namespace Common::X64 {
#ifdef _MSC_VER
__forceinline static u64 FencedRDTSC() {
_mm_lfence();
_ReadWriteBarrier();
const u64 result = __rdtsc();
_mm_lfence();
_ReadWriteBarrier();
return result;
}
__forceinline static void TPAUSE() {
// 100,000 cycles is a reasonable amount of time to wait to save on CPU resources.
// For reference:
// At 1 GHz, 100K cycles is 100us
// At 2 GHz, 100K cycles is 50us
// At 4 GHz, 100K cycles is 25us
static constexpr auto PauseCycles = 100'000;
_tpause(0, FencedRDTSC() + PauseCycles);
}
#else
static u64 FencedRDTSC() {
u64 eax;
u64 edx;
asm volatile("lfence\n\t"
"rdtsc\n\t"
"lfence\n\t"
: "=a"(eax), "=d"(edx));
return (edx << 32) | eax;
}
static void TPAUSE() {
// 100,000 cycles is a reasonable amount of time to wait to save on CPU resources.
// For reference:
// At 1 GHz, 100K cycles is 100us
// At 2 GHz, 100K cycles is 50us
// At 4 GHz, 100K cycles is 25us
static constexpr auto PauseCycles = 100'000;
const auto tsc = FencedRDTSC() + PauseCycles;
const auto eax = static_cast<u32>(tsc & 0xFFFFFFFF);
const auto edx = static_cast<u32>(tsc >> 32);
asm volatile("tpause %0" : : "r"(0), "d"(edx), "a"(eax));
}
#endif
void MicroSleep() {
static const bool has_waitpkg = GetCPUCaps().waitpkg;
if (has_waitpkg) {
TPAUSE();
} else {
std::this_thread::yield();
}
}
} // namespace Common::X64
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