// Copyright 2020 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <array>
#include <chrono>
#include <limits>
#include <mutex>
#include <thread>
#ifdef _MSC_VER
#include <intrin.h>
#pragma intrinsic(__umulh)
#pragma intrinsic(_udiv128)
#else
#include <x86intrin.h>
#endif
#include "common/uint128.h"
#include "common/x64/native_clock.h"
namespace {
[[nodiscard]] u64 GetFixedPoint64Factor(u64 numerator, u64 divisor) {
#ifdef __SIZEOF_INT128__
const auto base = static_cast<unsigned __int128>(numerator) << 64ULL;
return static_cast<u64>(base / divisor);
#elif defined(_M_X64) || defined(_M_ARM64)
std::array<u64, 2> r = {0, numerator};
u64 remainder;
#if _MSC_VER < 1923
return udiv128(r[1], r[0], divisor, &remainder);
#else
return _udiv128(r[1], r[0], divisor, &remainder);
#endif
#else
// This one is bit more inaccurate.
return MultiplyAndDivide64(std::numeric_limits<u64>::max(), numerator, divisor);
#endif
}
[[nodiscard]] u64 MultiplyHigh(u64 a, u64 b) {
#ifdef __SIZEOF_INT128__
return (static_cast<unsigned __int128>(a) * static_cast<unsigned __int128>(b)) >> 64;
#elif defined(_M_X64) || defined(_M_ARM64)
return __umulh(a, b); // MSVC
#else
// Generic fallback
const u64 a_lo = u32(a);
const u64 a_hi = a >> 32;
const u64 b_lo = u32(b);
const u64 b_hi = b >> 32;
const u64 a_x_b_hi = a_hi * b_hi;
const u64 a_x_b_mid = a_hi * b_lo;
const u64 b_x_a_mid = b_hi * a_lo;
const u64 a_x_b_lo = a_lo * b_lo;
const u64 carry_bit = (static_cast<u64>(static_cast<u32>(a_x_b_mid)) +
static_cast<u64>(static_cast<u32>(b_x_a_mid)) + (a_x_b_lo >> 32)) >>
32;
const u64 multhi = a_x_b_hi + (a_x_b_mid >> 32) + (b_x_a_mid >> 32) + carry_bit;
return multhi;
#endif
}
} // namespace
namespace Common {
u64 EstimateRDTSCFrequency() {
const auto milli_10 = std::chrono::milliseconds{10};
// get current time
_mm_mfence();
const u64 tscStart = __rdtsc();
const auto startTime = std::chrono::high_resolution_clock::now();
// wait roughly 3 seconds
while (true) {
auto milli = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::high_resolution_clock::now() - startTime);
if (milli.count() >= 3000)
break;
std::this_thread::sleep_for(milli_10);
}
const auto endTime = std::chrono::high_resolution_clock::now();
_mm_mfence();
const u64 tscEnd = __rdtsc();
// calculate difference
const u64 timer_diff =
std::chrono::duration_cast<std::chrono::nanoseconds>(endTime - startTime).count();
const u64 tsc_diff = tscEnd - tscStart;
const u64 tsc_freq = MultiplyAndDivide64(tsc_diff, 1000000000ULL, timer_diff);
return tsc_freq;
}
namespace X64 {
NativeClock::NativeClock(u64 emulated_cpu_frequency_, u64 emulated_clock_frequency_,
u64 rtsc_frequency_)
: WallClock(emulated_cpu_frequency_, emulated_clock_frequency_, true), rtsc_frequency{
rtsc_frequency_} {
_mm_mfence();
last_measure = __rdtsc();
accumulated_ticks = 0U;
ns_rtsc_factor = GetFixedPoint64Factor(1000000000, rtsc_frequency);
us_rtsc_factor = GetFixedPoint64Factor(1000000, rtsc_frequency);
ms_rtsc_factor = GetFixedPoint64Factor(1000, rtsc_frequency);
clock_rtsc_factor = GetFixedPoint64Factor(emulated_clock_frequency, rtsc_frequency);
cpu_rtsc_factor = GetFixedPoint64Factor(emulated_cpu_frequency, rtsc_frequency);
}
u64 NativeClock::GetRTSC() {
std::scoped_lock scope{rtsc_serialize};
_mm_mfence();
const u64 current_measure = __rdtsc();
u64 diff = current_measure - last_measure;
diff = diff & ~static_cast<u64>(static_cast<s64>(diff) >> 63); // max(diff, 0)
if (current_measure > last_measure) {
last_measure = current_measure;
}
accumulated_ticks += diff;
/// The clock cannot be more precise than the guest timer, remove the lower bits
return accumulated_ticks & inaccuracy_mask;
}
void NativeClock::Pause(bool is_paused) {
if (!is_paused) {
_mm_mfence();
last_measure = __rdtsc();
}
}
std::chrono::nanoseconds NativeClock::GetTimeNS() {
const u64 rtsc_value = GetRTSC();
return std::chrono::nanoseconds{MultiplyHigh(rtsc_value, ns_rtsc_factor)};
}
std::chrono::microseconds NativeClock::GetTimeUS() {
const u64 rtsc_value = GetRTSC();
return std::chrono::microseconds{MultiplyHigh(rtsc_value, us_rtsc_factor)};
}
std::chrono::milliseconds NativeClock::GetTimeMS() {
const u64 rtsc_value = GetRTSC();
return std::chrono::milliseconds{MultiplyHigh(rtsc_value, ms_rtsc_factor)};
}
u64 NativeClock::GetClockCycles() {
const u64 rtsc_value = GetRTSC();
return MultiplyHigh(rtsc_value, clock_rtsc_factor);
}
u64 NativeClock::GetCPUCycles() {
const u64 rtsc_value = GetRTSC();
return MultiplyHigh(rtsc_value, cpu_rtsc_factor);
}
} // namespace X64
} // namespace Common
