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Diffstat (limited to '')
-rw-r--r-- | src/common/steady_clock.cpp | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/src/common/steady_clock.cpp b/src/common/steady_clock.cpp new file mode 100644 index 000000000..9415eed29 --- /dev/null +++ b/src/common/steady_clock.cpp @@ -0,0 +1,80 @@ +// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project +// SPDX-License-Identifier: GPL-2.0-or-later + +#if defined(_WIN32) +#include <windows.h> +#else +#include <time.h> +#endif + +#include "common/steady_clock.h" + +namespace Common { + +#ifdef _WIN32 +static s64 WindowsQueryPerformanceFrequency() { + LARGE_INTEGER frequency; + QueryPerformanceFrequency(&frequency); + return frequency.QuadPart; +} + +static s64 WindowsQueryPerformanceCounter() { + LARGE_INTEGER counter; + QueryPerformanceCounter(&counter); + return counter.QuadPart; +} + +static s64 GetSystemTimeNS() { + // GetSystemTimePreciseAsFileTime returns the file time in 100ns units. + static constexpr s64 Multiplier = 100; + // Convert Windows epoch to Unix epoch. + static constexpr s64 WindowsEpochToUnixEpoch = 0x19DB1DED53E8000LL; + + FILETIME filetime; + GetSystemTimePreciseAsFileTime(&filetime); + return Multiplier * ((static_cast<s64>(filetime.dwHighDateTime) << 32) + + static_cast<s64>(filetime.dwLowDateTime) - WindowsEpochToUnixEpoch); +} +#endif + +SteadyClock::time_point SteadyClock::Now() noexcept { +#if defined(_WIN32) + static const auto freq = WindowsQueryPerformanceFrequency(); + const auto counter = WindowsQueryPerformanceCounter(); + + // 10 MHz is a very common QPC frequency on modern PCs. + // Optimizing for this specific frequency can double the performance of + // this function by avoiding the expensive frequency conversion path. + static constexpr s64 TenMHz = 10'000'000; + + if (freq == TenMHz) [[likely]] { + static_assert(period::den % TenMHz == 0); + static constexpr s64 Multiplier = period::den / TenMHz; + return time_point{duration{counter * Multiplier}}; + } + + const auto whole = (counter / freq) * period::den; + const auto part = (counter % freq) * period::den / freq; + return time_point{duration{whole + part}}; +#elif defined(__APPLE__) + return time_point{duration{clock_gettime_nsec_np(CLOCK_MONOTONIC_RAW)}}; +#else + timespec ts; + clock_gettime(CLOCK_MONOTONIC, &ts); + return time_point{std::chrono::seconds{ts.tv_sec} + std::chrono::nanoseconds{ts.tv_nsec}}; +#endif +} + +RealTimeClock::time_point RealTimeClock::Now() noexcept { +#if defined(_WIN32) + return time_point{duration{GetSystemTimeNS()}}; +#elif defined(__APPLE__) + return time_point{duration{clock_gettime_nsec_np(CLOCK_REALTIME)}}; +#else + timespec ts; + clock_gettime(CLOCK_REALTIME, &ts); + return time_point{std::chrono::seconds{ts.tv_sec} + std::chrono::nanoseconds{ts.tv_nsec}}; +#endif +} + +}; // namespace Common |