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use NtDelayExecution for SDL_SYS_DelayNS #13816

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use NtDelayExecution for SDL_SYS_DelayNS #13816

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38 changes: 38 additions & 0 deletions src/timer/windows/SDL_systimer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -103,6 +103,42 @@ Uint64 SDL_GetPerformanceFrequency(void)
return (Uint64)frequency.QuadPart;
}

#ifdef SDL_TIMER_WINDOWS_USE_NTDELAYEXECUTION

typedef LONG (NTAPI *NtDelayExecution_t)(BOOLEAN Alertable, PLARGE_INTEGER DelayInterval);
static NtDelayExecution_t pNtDelayExecution;

static void SDL_NtDelayExecution(BOOLEAN Alertable, PLARGE_INTEGER DelayInterval)
{
if (!pNtDelayExecution) {
static bool initialized;

if (!initialized) {
HMODULE module = GetModuleHandle(TEXT("ntdll.dll"));
if (module) {
pNtDelayExecution = (NtDelayExecution_t)GetProcAddress(module, "NtDelayExecution");
}
initialized = true;
}

if (!pNtDelayExecution) {
return;
}
}

pNtDelayExecution(Alertable, DelayInterval);
}

void SDL_SYS_DelayNS(Uint64 ns)
{
Sint64 tick = ns;
tick /= 100;
tick *= -1;
SDL_NtDelayExecution(0, (PLARGE_INTEGER)&tick);
}

#else

void SDL_SYS_DelayNS(Uint64 ns)
{
HANDLE timer = SDL_GetWaitableTimer();
Expand Down Expand Up @@ -130,4 +166,6 @@ void SDL_SYS_DelayNS(Uint64 ns)
Sleep(delay);
}

#endif // SDL_TIMER_WINDOWS_USE_NTDELAYEXECUTION

#endif // SDL_TIMER_WINDOWS
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