use NtDelayExecution for SDL_SYS_DelayNS

Author: expikr

src/timer/windows/SDL_systimer.c

@@ -29,64 +29,6 @@
 #define CREATE_WAITABLE_TIMER_HIGH_RESOLUTION 0x2
 #endif
 
-typedef HANDLE (WINAPI *CreateWaitableTimerExW_t)(LPSECURITY_ATTRIBUTES lpTimerAttributes, LPCWSTR lpTimerName, DWORD dwFlags, DWORD dwDesiredAccess);
-static CreateWaitableTimerExW_t pCreateWaitableTimerExW;
-
-typedef BOOL (WINAPI *SetWaitableTimerEx_t)(HANDLE hTimer, const LARGE_INTEGER *lpDueTime, LONG lPeriod, PTIMERAPCROUTINE pfnCompletionRoutine, LPVOID lpArgToCompletionRoutine, PREASON_CONTEXT WakeContext, ULONG TolerableDelay);
-static SetWaitableTimerEx_t pSetWaitableTimerEx;
-
-static void SDL_CleanupWaitableHandle(void *handle)
-{
-    CloseHandle(handle);
-}
-
-static HANDLE SDL_GetWaitableTimer(void)
-{
-    static SDL_TLSID TLS_timer_handle;
-    HANDLE timer;
-
-    if (!pCreateWaitableTimerExW || !pSetWaitableTimerEx) {
-        static bool initialized;
-
-        if (!initialized) {
-            HMODULE module = GetModuleHandle(TEXT("kernel32.dll"));
-            if (module) {
-                pCreateWaitableTimerExW = (CreateWaitableTimerExW_t)GetProcAddress(module, "CreateWaitableTimerExW");
-                pSetWaitableTimerEx = (SetWaitableTimerEx_t)GetProcAddress(module, "SetWaitableTimerEx");
-            }
-            initialized = true;
-        }
-
-        if (!pCreateWaitableTimerExW || !pSetWaitableTimerEx) {
-            return NULL;
-        }
-    }
-
-    timer = SDL_GetTLS(&TLS_timer_handle);
-    if (!timer) {
-        timer = pCreateWaitableTimerExW(NULL, NULL, CREATE_WAITABLE_TIMER_HIGH_RESOLUTION, TIMER_ALL_ACCESS);
-        if (timer) {
-            SDL_SetTLS(&TLS_timer_handle, timer, SDL_CleanupWaitableHandle);
-        }
-    }
-    return timer;
-}
-
-static HANDLE SDL_GetWaitableEvent(void)
-{
-    static SDL_TLSID TLS_event_handle;
-    HANDLE event;
-
-    event = SDL_GetTLS(&TLS_event_handle);
-    if (!event) {
-        event = CreateEvent(NULL, FALSE, FALSE, NULL);
-        if (event) {
-            SDL_SetTLS(&TLS_event_handle, event, SDL_CleanupWaitableHandle);
-        }
-    }
-    return event;
-}
-
 Uint64 SDL_GetPerformanceCounter(void)
 {
     LARGE_INTEGER counter;
@@ -103,31 +45,35 @@ Uint64 SDL_GetPerformanceFrequency(void)
     return (Uint64)frequency.QuadPart;
 }
 
-void SDL_SYS_DelayNS(Uint64 ns)
+typedef DWORD (NTAPI *NtDelayExecution_t)(BOOLEAN Alertable, PLARGE_INTEGER DelayInterval);
+static NtDelayExecution_t pNtDelayExecution;
+static void SDL_NtDelayExecution(BOOLEAN Alertable, PLARGE_INTEGER DelayInterval)
 {
-    HANDLE timer = SDL_GetWaitableTimer();
-    if (timer) {
-        LARGE_INTEGER due_time;
-        due_time.QuadPart = -((LONGLONG)ns / 100);
-        if (pSetWaitableTimerEx(timer, &due_time, 0, NULL, NULL, NULL, 0)) {
-            WaitForSingleObject(timer, INFINITE);
+    if (!pNtDelayExecution) {
+        static bool initialized;
+
+        if (!initialized) {
+            HMODULE module = GetModuleHandle(TEXT("ntdll.dll"));
+            if (module) {
+                pNtDelayExecution = (NtDelayExecution_t)GetProcAddress(module, "NtDelayExecution");
+            }
+            initialized = true;
         }
-        return;
-    }
 
-    const Uint64 max_delay = 0xffffffffLL * SDL_NS_PER_MS;
-    if (ns > max_delay) {
-        ns = max_delay;
+        if (!pNtDelayExecution) {
+            return;
+        }
     }
-    const DWORD delay = (DWORD)SDL_NS_TO_MS(ns);
 
-    HANDLE event = SDL_GetWaitableEvent();
-    if (event) {
-        WaitForSingleObjectEx(event, delay, FALSE);
-        return;
-    }
+    pNtDelayExecution(Alertable, DelayInterval);
+}
 
-    Sleep(delay);
+void SDL_SYS_DelayNS(Uint64 ns)
+{
+    Sint64 tick = ns;
+    tick /= 100;
+    tick *= -1;
+    SDL_NtDelayExecution(0, (PLARGE_INTEGER)&tick);
 }
 
 #endif // SDL_TIMER_WINDOWS