118 lines
4.4 KiB
C++
118 lines
4.4 KiB
C++
// Copyright 2020 yuzu Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <array>
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#include <chrono>
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#include <limits>
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#include <mutex>
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#include <thread>
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#include "common/atomic_ops.h"
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#include "common/uint128.h"
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#include "common/x64/native_clock.h"
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namespace Common {
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u64 EstimateRDTSCFrequency() {
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// Discard the first result measuring the rdtsc.
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_mm_mfence();
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__rdtsc();
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std::this_thread::sleep_for(std::chrono::milliseconds{1});
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_mm_mfence();
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__rdtsc();
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// Get the current time.
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const auto start_time = std::chrono::steady_clock::now();
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_mm_mfence();
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const u64 tsc_start = __rdtsc();
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// Wait for 200 milliseconds.
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std::this_thread::sleep_for(std::chrono::milliseconds{200});
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const auto end_time = std::chrono::steady_clock::now();
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_mm_mfence();
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const u64 tsc_end = __rdtsc();
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// Calculate differences.
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const u64 timer_diff = static_cast<u64>(
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std::chrono::duration_cast<std::chrono::nanoseconds>(end_time - start_time).count());
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const u64 tsc_diff = tsc_end - tsc_start;
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const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff);
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return tsc_freq;
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}
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namespace X64 {
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NativeClock::NativeClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_,
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u64 rtsc_frequency_)
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: WallClock(emulated_cpu_frequency_, emulated_clock_frequency_, true), rtsc_frequency{
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rtsc_frequency_} {
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_mm_mfence();
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time_point.inner.last_measure = __rdtsc();
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time_point.inner.accumulated_ticks = 0U;
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ns_rtsc_factor = GetFixedPoint64Factor(NS_RATIO, rtsc_frequency);
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us_rtsc_factor = GetFixedPoint64Factor(US_RATIO, rtsc_frequency);
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ms_rtsc_factor = GetFixedPoint64Factor(MS_RATIO, rtsc_frequency);
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clock_rtsc_factor = GetFixedPoint64Factor(emulated_clock_frequency, rtsc_frequency);
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cpu_rtsc_factor = GetFixedPoint64Factor(emulated_cpu_frequency, rtsc_frequency);
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}
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u64 NativeClock::GetRTSC() {
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TimePoint new_time_point{};
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TimePoint current_time_point{};
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do {
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current_time_point.pack = time_point.pack;
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_mm_mfence();
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const u64 current_measure = __rdtsc();
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u64 diff = current_measure - current_time_point.inner.last_measure;
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diff = diff & ~static_cast<u64>(static_cast<s64>(diff) >> 63); // max(diff, 0)
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new_time_point.inner.last_measure = current_measure > current_time_point.inner.last_measure
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? current_measure
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: current_time_point.inner.last_measure;
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new_time_point.inner.accumulated_ticks = current_time_point.inner.accumulated_ticks + diff;
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} while (!Common::AtomicCompareAndSwap(time_point.pack.data(), new_time_point.pack,
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current_time_point.pack));
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/// The clock cannot be more precise than the guest timer, remove the lower bits
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return new_time_point.inner.accumulated_ticks & inaccuracy_mask;
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}
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void NativeClock::Pause(bool is_paused) {
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if (!is_paused) {
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TimePoint current_time_point{};
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TimePoint new_time_point{};
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do {
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current_time_point.pack = time_point.pack;
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new_time_point.pack = current_time_point.pack;
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_mm_mfence();
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new_time_point.inner.last_measure = __rdtsc();
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} while (!Common::AtomicCompareAndSwap(time_point.pack.data(), new_time_point.pack,
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current_time_point.pack));
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}
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}
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std::chrono::nanoseconds NativeClock::GetTimeNS() {
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const u64 rtsc_value = GetRTSC();
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return std::chrono::nanoseconds{MultiplyHigh(rtsc_value, ns_rtsc_factor)};
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}
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std::chrono::microseconds NativeClock::GetTimeUS() {
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const u64 rtsc_value = GetRTSC();
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return std::chrono::microseconds{MultiplyHigh(rtsc_value, us_rtsc_factor)};
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}
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std::chrono::milliseconds NativeClock::GetTimeMS() {
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const u64 rtsc_value = GetRTSC();
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return std::chrono::milliseconds{MultiplyHigh(rtsc_value, ms_rtsc_factor)};
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}
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u64 NativeClock::GetClockCycles() {
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const u64 rtsc_value = GetRTSC();
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return MultiplyHigh(rtsc_value, clock_rtsc_factor);
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}
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u64 NativeClock::GetCPUCycles() {
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const u64 rtsc_value = GetRTSC();
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return MultiplyHigh(rtsc_value, cpu_rtsc_factor);
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}
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} // namespace X64
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} // namespace Common
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