From bd09c825218aac9255643b9aa7c75f5ba156038c Mon Sep 17 00:00:00 2001 From: Morph <39850852+Morph1984@users.noreply.github.com> Date: Wed, 1 Mar 2023 19:17:50 -0500 Subject: [PATCH] common: Implement a high resolution steady clock This implementation provides a consistent, high performance, and high resolution clock where/when std::chrono::steady_clock does not provide sufficient precision. --- src/common/CMakeLists.txt | 2 ++ src/common/steady_clock.cpp | 56 +++++++++++++++++++++++++++++++++++++ src/common/steady_clock.h | 23 +++++++++++++++ 3 files changed, 81 insertions(+) create mode 100644 src/common/steady_clock.cpp create mode 100644 src/common/steady_clock.h diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt index 56b247ac47..9f5d4c2653 100644 --- a/src/common/CMakeLists.txt +++ b/src/common/CMakeLists.txt @@ -113,6 +113,8 @@ add_library(common STATIC socket_types.h spin_lock.cpp spin_lock.h + steady_clock.cpp + steady_clock.h stream.cpp stream.h string_util.cpp diff --git a/src/common/steady_clock.cpp b/src/common/steady_clock.cpp new file mode 100644 index 0000000000..0d5908aa79 --- /dev/null +++ b/src/common/steady_clock.cpp @@ -0,0 +1,56 @@ +// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project +// SPDX-License-Identifier: GPL-2.0-or-later + +#if defined(_WIN32) +#include +#else +#include +#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; +} +#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 +} + +}; // namespace Common diff --git a/src/common/steady_clock.h b/src/common/steady_clock.h new file mode 100644 index 0000000000..9497cf865d --- /dev/null +++ b/src/common/steady_clock.h @@ -0,0 +1,23 @@ +// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project +// SPDX-License-Identifier: GPL-2.0-or-later + +#pragma once + +#include + +#include "common/common_types.h" + +namespace Common { + +struct SteadyClock { + using rep = s64; + using period = std::nano; + using duration = std::chrono::nanoseconds; + using time_point = std::chrono::time_point; + + static constexpr bool is_steady = true; + + [[nodiscard]] static time_point Now() noexcept; +}; + +} // namespace Common