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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"
#include "common/x64/rdtsc.h"
namespace Common::X64 {
namespace {
// 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
constexpr auto PauseCycles = 100'000U;
} // Anonymous namespace
#ifdef _MSC_VER
__forceinline static void TPAUSE() {
static constexpr auto RequestC02State = 0U;
_tpause(RequestC02State, FencedRDTSC() + PauseCycles);
}
__forceinline static void MWAITX() {
static constexpr auto EnableWaitTimeFlag = 1U << 1;
static constexpr auto RequestC1State = 0U;
// monitor_var should be aligned to a cache line.
alignas(64) u64 monitor_var{};
_mm_monitorx(&monitor_var, 0, 0);
_mm_mwaitx(EnableWaitTimeFlag, RequestC1State, PauseCycles);
}
#else
static void TPAUSE() {
static constexpr auto RequestC02State = 0U;
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"(RequestC02State), "d"(edx), "a"(eax));
}
static void MWAITX() {
static constexpr auto EnableWaitTimeFlag = 1U << 1;
static constexpr auto RequestC1State = 0U;
// monitor_var should be aligned to a cache line.
alignas(64) u64 monitor_var{};
asm volatile("monitorx" : : "a"(&monitor_var), "c"(0), "d"(0));
asm volatile("mwaitx" : : "a"(RequestC1State), "b"(PauseCycles), "c"(EnableWaitTimeFlag));
}
#endif
void MicroSleep() {
static const bool has_waitpkg = GetCPUCaps().waitpkg;
static const bool has_monitorx = GetCPUCaps().monitorx;
if (has_waitpkg) {
TPAUSE();
} else if (has_monitorx) {
MWAITX();
} else {
std::this_thread::yield();
}
}
} // namespace Common::X64
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