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-rw-r--r--src/common/windows/timer_resolution.cpp109
1 files changed, 109 insertions, 0 deletions
diff --git a/src/common/windows/timer_resolution.cpp b/src/common/windows/timer_resolution.cpp
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+++ b/src/common/windows/timer_resolution.cpp
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+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <windows.h>
+
+#include "common/windows/timer_resolution.h"
+
+extern "C" {
+// http://undocumented.ntinternals.net/index.html?page=UserMode%2FUndocumented%20Functions%2FTime%2FNtQueryTimerResolution.html
+NTSYSAPI LONG NTAPI NtQueryTimerResolution(PULONG MinimumResolution, PULONG MaximumResolution,
+ PULONG CurrentResolution);
+
+// http://undocumented.ntinternals.net/index.html?page=UserMode%2FUndocumented%20Functions%2FTime%2FNtSetTimerResolution.html
+NTSYSAPI LONG NTAPI NtSetTimerResolution(ULONG DesiredResolution, BOOLEAN SetResolution,
+ PULONG CurrentResolution);
+
+// http://undocumented.ntinternals.net/index.html?page=UserMode%2FUndocumented%20Functions%2FNT%20Objects%2FThread%2FNtDelayExecution.html
+NTSYSAPI LONG NTAPI NtDelayExecution(BOOLEAN Alertable, PLARGE_INTEGER DelayInterval);
+}
+
+// Defines for compatibility with older Windows 10 SDKs.
+
+#ifndef PROCESS_POWER_THROTTLING_EXECUTION_SPEED
+#define PROCESS_POWER_THROTTLING_EXECUTION_SPEED 0x1
+#endif
+#ifndef PROCESS_POWER_THROTTLING_IGNORE_TIMER_RESOLUTION
+#define PROCESS_POWER_THROTTLING_IGNORE_TIMER_RESOLUTION 0x4
+#endif
+
+namespace Common::Windows {
+
+namespace {
+
+using namespace std::chrono;
+
+constexpr nanoseconds ToNS(ULONG hundred_ns) {
+ return nanoseconds{hundred_ns * 100};
+}
+
+constexpr ULONG ToHundredNS(nanoseconds ns) {
+ return static_cast<ULONG>(ns.count()) / 100;
+}
+
+struct TimerResolution {
+ std::chrono::nanoseconds minimum;
+ std::chrono::nanoseconds maximum;
+ std::chrono::nanoseconds current;
+};
+
+TimerResolution GetTimerResolution() {
+ ULONG MinimumTimerResolution;
+ ULONG MaximumTimerResolution;
+ ULONG CurrentTimerResolution;
+ NtQueryTimerResolution(&MinimumTimerResolution, &MaximumTimerResolution,
+ &CurrentTimerResolution);
+ return {
+ .minimum{ToNS(MinimumTimerResolution)},
+ .maximum{ToNS(MaximumTimerResolution)},
+ .current{ToNS(CurrentTimerResolution)},
+ };
+}
+
+void SetHighQoS() {
+ // https://learn.microsoft.com/en-us/windows/win32/procthread/quality-of-service
+ PROCESS_POWER_THROTTLING_STATE PowerThrottling{
+ .Version{PROCESS_POWER_THROTTLING_CURRENT_VERSION},
+ .ControlMask{PROCESS_POWER_THROTTLING_EXECUTION_SPEED |
+ PROCESS_POWER_THROTTLING_IGNORE_TIMER_RESOLUTION},
+ .StateMask{},
+ };
+ SetProcessInformation(GetCurrentProcess(), ProcessPowerThrottling, &PowerThrottling,
+ sizeof(PROCESS_POWER_THROTTLING_STATE));
+}
+
+} // Anonymous namespace
+
+nanoseconds GetMinimumTimerResolution() {
+ return GetTimerResolution().minimum;
+}
+
+nanoseconds GetMaximumTimerResolution() {
+ return GetTimerResolution().maximum;
+}
+
+nanoseconds GetCurrentTimerResolution() {
+ return GetTimerResolution().current;
+}
+
+nanoseconds SetCurrentTimerResolution(nanoseconds timer_resolution) {
+ // Set the timer resolution, and return the current timer resolution.
+ const auto DesiredTimerResolution = ToHundredNS(timer_resolution);
+ ULONG CurrentTimerResolution;
+ NtSetTimerResolution(DesiredTimerResolution, TRUE, &CurrentTimerResolution);
+ return ToNS(CurrentTimerResolution);
+}
+
+nanoseconds SetCurrentTimerResolutionToMaximum() {
+ SetHighQoS();
+ return SetCurrentTimerResolution(GetMaximumTimerResolution());
+}
+
+void SleepForOneTick() {
+ LARGE_INTEGER DelayInterval{
+ .QuadPart{-1},
+ };
+ NtDelayExecution(FALSE, &DelayInterval);
+}
+
+} // namespace Common::Windows