From cf9e217e7b1cf78b949b52d7a2f6d38ca9d43d85 Mon Sep 17 00:00:00 2001
From: Joshua Ashton <joshua@froggi.es>
Date: Tue, 16 Aug 2022 08:57:40 +0000
Subject: [PATCH] [util] Support for fps limiter on non-Windows platforms

Defaults to a sleep granularity of 0.5ms, which is slightly on the cautious side.

Calls through to std::this_thread::sleep_for directly, which calls through to nanosleep.
---
 src/util/util_fps_limiter.cpp | 9 +++++++++
 src/util/util_fps_limiter.h   | 9 +++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/util/util_fps_limiter.cpp b/src/util/util_fps_limiter.cpp
index 9354d6634..f7255a2d4 100644
--- a/src/util/util_fps_limiter.cpp
+++ b/src/util/util_fps_limiter.cpp
@@ -140,6 +140,7 @@ namespace dxvk {
 
 
   void FpsLimiter::updateSleepGranularity() {
+#ifdef _WIN32
     HMODULE ntdll = ::GetModuleHandleW(L"ntdll.dll");
 
     if (ntdll) {
@@ -166,10 +167,15 @@ namespace dxvk {
       // Assume 1ms sleep granularity by default
       m_sleepGranularity = TimerDuration(1ms);
     }
+#else
+    // Assume 0.5ms sleep granularity by default
+    m_sleepGranularity = TimerDuration(500us);
+#endif
   }
 
 
   void FpsLimiter::performSleep(TimerDuration sleepDuration) {
+#ifdef _WIN32
     if (NtDelayExecution) {
       LARGE_INTEGER ticks;
       ticks.QuadPart = -sleepDuration.count();
@@ -178,6 +184,9 @@ namespace dxvk {
     } else {
       std::this_thread::sleep_for(sleepDuration);
     }
+#else
+    std::this_thread::sleep_for(sleepDuration);
+#endif
   }
 
 }
diff --git a/src/util/util_fps_limiter.h b/src/util/util_fps_limiter.h
index 94890c2ce..a45f3c0e9 100644
--- a/src/util/util_fps_limiter.h
+++ b/src/util/util_fps_limiter.h
@@ -60,10 +60,17 @@ namespace dxvk {
 
     using TimePoint = dxvk::high_resolution_clock::time_point;
 
+#ifdef _WIN32
+    // On Windows, we use NtDelayExecution which has units of 100ns.
     using TimerDuration = std::chrono::duration<int64_t, std::ratio<1, 10000000>>;
     using NtQueryTimerResolutionProc = UINT (WINAPI *) (ULONG*, ULONG*, ULONG*);
     using NtSetTimerResolutionProc = UINT (WINAPI *) (ULONG, BOOL, ULONG*);
     using NtDelayExecutionProc = UINT (WINAPI *) (BOOL, LARGE_INTEGER*);
+    NtDelayExecutionProc NtDelayExecution = nullptr;
+#else
+    // On other platforms, we use the std library, which calls through to nanosleep -- which is ns.
+    using TimerDuration = std::chrono::nanoseconds;
+#endif
 
     dxvk::mutex     m_mutex;
 
@@ -78,8 +85,6 @@ namespace dxvk {
     TimerDuration   m_sleepGranularity = TimerDuration::zero();
     TimerDuration   m_sleepThreshold   = TimerDuration::zero();
 
-    NtDelayExecutionProc NtDelayExecution = nullptr;
-
     TimePoint sleep(TimePoint t0, TimerDuration duration);
 
     void initialize();