137 lines
4.8 KiB
C++
137 lines
4.8 KiB
C++
// SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
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// SPDX-License-Identifier: GPL-2.0-or-later
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#include <array>
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#include <chrono>
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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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#ifdef _MSC_VER
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#include <intrin.h>
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#endif
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namespace Common {
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#ifdef _MSC_VER
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__forceinline static u64 FencedRDTSC() {
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_mm_lfence();
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_ReadWriteBarrier();
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const u64 result = __rdtsc();
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_mm_lfence();
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_ReadWriteBarrier();
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return result;
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}
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#else
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static u64 FencedRDTSC() {
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u64 result;
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asm volatile("lfence\n\t"
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"rdtsc\n\t"
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"shl $32, %%rdx\n\t"
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"or %%rdx, %0\n\t"
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"lfence"
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: "=a"(result)
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:
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: "rdx", "memory", "cc");
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return result;
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}
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#endif
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u64 EstimateRDTSCFrequency() {
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// Discard the first result measuring the rdtsc.
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FencedRDTSC();
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std::this_thread::sleep_for(std::chrono::milliseconds{1});
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FencedRDTSC();
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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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const u64 tsc_start = FencedRDTSC();
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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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const u64 tsc_end = FencedRDTSC();
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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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TimePoint new_time_point{};
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new_time_point.last_measure = FencedRDTSC();
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new_time_point.accumulated_ticks = 0U;
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time_point.store(new_time_point);
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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 = time_point.load(std::memory_order_acquire);
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do {
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const u64 current_measure = FencedRDTSC();
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u64 diff = current_measure - current_time_point.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.last_measure = current_measure > current_time_point.last_measure
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? current_measure
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: current_time_point.last_measure;
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new_time_point.accumulated_ticks = current_time_point.accumulated_ticks + diff;
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} while (!time_point.compare_exchange_weak(
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current_time_point, new_time_point, std::memory_order_release, std::memory_order_acquire));
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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.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 new_time_point{};
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TimePoint current_time_point = time_point.load(std::memory_order_acquire);
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do {
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new_time_point = current_time_point;
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new_time_point.last_measure = FencedRDTSC();
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} while (!time_point.compare_exchange_weak(current_time_point, new_time_point,
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std::memory_order_release,
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std::memory_order_acquire));
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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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