6267110b69
In addition to requiring nanosecond precision, using the native clock requires that the hardware TSC has a precision greater than the emulated CPU and its clock counter.
99 lines
3.4 KiB
C++
99 lines
3.4 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 <cstdint>
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#include "common/uint128.h"
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#include "common/wall_clock.h"
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#ifdef ARCHITECTURE_x86_64
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#include "common/x64/cpu_detect.h"
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#include "common/x64/native_clock.h"
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#endif
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namespace Common {
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using base_timer = std::chrono::steady_clock;
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using base_time_point = std::chrono::time_point<base_timer>;
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class StandardWallClock final : public WallClock {
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public:
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explicit StandardWallClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_)
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: WallClock(emulated_cpu_frequency_, emulated_clock_frequency_, false) {
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start_time = base_timer::now();
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}
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std::chrono::nanoseconds GetTimeNS() override {
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base_time_point current = base_timer::now();
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auto elapsed = current - start_time;
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return std::chrono::duration_cast<std::chrono::nanoseconds>(elapsed);
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}
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std::chrono::microseconds GetTimeUS() override {
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base_time_point current = base_timer::now();
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auto elapsed = current - start_time;
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return std::chrono::duration_cast<std::chrono::microseconds>(elapsed);
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}
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std::chrono::milliseconds GetTimeMS() override {
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base_time_point current = base_timer::now();
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auto elapsed = current - start_time;
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return std::chrono::duration_cast<std::chrono::milliseconds>(elapsed);
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}
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u64 GetClockCycles() override {
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std::chrono::nanoseconds time_now = GetTimeNS();
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const u128 temporary =
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Common::Multiply64Into128(time_now.count(), emulated_clock_frequency);
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return Common::Divide128On32(temporary, 1000000000).first;
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}
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u64 GetCPUCycles() override {
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std::chrono::nanoseconds time_now = GetTimeNS();
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const u128 temporary = Common::Multiply64Into128(time_now.count(), emulated_cpu_frequency);
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return Common::Divide128On32(temporary, 1000000000).first;
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}
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void Pause([[maybe_unused]] bool is_paused) override {
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// Do nothing in this clock type.
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}
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private:
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base_time_point start_time;
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};
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#ifdef ARCHITECTURE_x86_64
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std::unique_ptr<WallClock> CreateBestMatchingClock(u64 emulated_cpu_frequency,
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u64 emulated_clock_frequency) {
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const auto& caps = GetCPUCaps();
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u64 rtsc_frequency = 0;
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if (caps.invariant_tsc) {
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rtsc_frequency = EstimateRDTSCFrequency();
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}
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// Fallback to StandardWallClock if the hardware TSC does not have the precision greater than:
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// - A nanosecond
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// - The emulated CPU frequency
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// - The emulated clock counter frequency (CNTFRQ)
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if (rtsc_frequency <= WallClock::NS_RATIO || rtsc_frequency <= emulated_cpu_frequency ||
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rtsc_frequency <= emulated_clock_frequency) {
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return std::make_unique<StandardWallClock>(emulated_cpu_frequency,
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emulated_clock_frequency);
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} else {
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return std::make_unique<X64::NativeClock>(emulated_cpu_frequency, emulated_clock_frequency,
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rtsc_frequency);
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}
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}
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#else
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std::unique_ptr<WallClock> CreateBestMatchingClock(u64 emulated_cpu_frequency,
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u64 emulated_clock_frequency) {
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return std::make_unique<StandardWallClock>(emulated_cpu_frequency, emulated_clock_frequency);
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}
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#endif
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} // namespace Common
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