2 files changed, 147 insertions, 0 deletions

diff --git a/src/common/windows/timer_resolution.cpp b/src/common/windows/timer_resolution.cpp
new file mode 100644
index 000000000..29c6e5c7e
--- /dev/null
+++ b/src/common/windows/timer_resolution.cpp
@@ -0,0 +1,109 @@
+// 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
diff --git a/src/common/windows/timer_resolution.h b/src/common/windows/timer_resolution.h
new file mode 100644
index 000000000..e1e50a62d
--- /dev/null
+++ b/src/common/windows/timer_resolution.h
@@ -0,0 +1,38 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <chrono>
+
+namespace Common::Windows {
+
+/// Returns the minimum (least precise) supported timer resolution in nanoseconds.
+std::chrono::nanoseconds GetMinimumTimerResolution();
+
+/// Returns the maximum (most precise) supported timer resolution in nanoseconds.
+std::chrono::nanoseconds GetMaximumTimerResolution();
+
+/// Returns the current timer resolution in nanoseconds.
+std::chrono::nanoseconds GetCurrentTimerResolution();
+
+/**
+ * Sets the current timer resolution.
+ *
+ * @param timer_resolution Timer resolution in nanoseconds.
+ *
+ * @returns The current timer resolution.
+ */
+std::chrono::nanoseconds SetCurrentTimerResolution(std::chrono::nanoseconds timer_resolution);
+
+/**
+ * Sets the current timer resolution to the maximum supported timer resolution.
+ *
+ * @returns The current timer resolution.
+ */
+std::chrono::nanoseconds SetCurrentTimerResolutionToMaximum();
+
+/// Sleep for one tick of the current timer resolution.
+void SleepForOneTick();
+
+} // namespace Common::Windows