Change Windows mainloop to microseconds.

While at it have another look at it's Sys_*seconds() implementations.
Also add a Sys_Nanosleep() and use it to throttle the game a litte bit.

src/backends/unix/main.c

@@ -41,6 +41,7 @@ main(int argc, char **argv)
 	int verLen, i;
 	long long oldtime, newtime;
 	const char* versionString;
+	struct timespec t = {0, 5000};
 
 	/* register signal handler */
 	registerHandler();
@@ -135,7 +136,7 @@ main(int argc, char **argv)
 	/* The mainloop. The legend. */
 	while (1)
 	{
-		struct timespec t = {0, 5000};
+		// Throttle the game a little bit.
 		nanosleep(&t, NULL);
 
 		newtime = Sys_Microseconds();

src/backends/unix/system.c

@@ -44,6 +44,7 @@
 #include <errno.h>
 #include <dlfcn.h>
 #include <dirent.h>
+#include <time.h>
 
 #include "../../common/header/common.h"
 #include "../../common/header/glob.h"
@@ -85,21 +86,24 @@ Sys_Microseconds(void)
 	static struct timespec last;
 	struct timespec now;
 
-	clock_gettime(CLOCK_REALTIME, &now);
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
 	if(last.tv_sec == 0)
 	{
-		clock_gettime(CLOCK_REALTIME, &last);
+		clock_gettime(CLOCK_MONOTONIC, &last);
 		return last.tv_nsec / 1000ll;
 	}
 
 	long long sec = now.tv_sec - last.tv_sec;
 	long long nsec = now.tv_nsec - last.tv_nsec;
+
 	if(nsec < 0)
 	{
 		nsec += 1000000000ll; // 1s in ns
 		--sec;
 	}
 
+	curtime = (int)((sec*1000000ll + nsec/1000ll) / 1000ll);
 	return sec*1000000ll + nsec/1000ll;
 }
 

src/backends/windows/system.c

@@ -414,28 +414,10 @@ ParseCommandLine(LPSTR lpCmdLine)
 
 /* ======================================================================= */
 
-int
-Sys_Milliseconds(void)
-{
-	static int base;
-	static qboolean initialized = false;
-
-	if (!initialized)
-	{   /* let base retain 16 bits of effectively random data */
-		base = timeGetTime() & 0xffff0000;
-		initialized = true;
-	}
-
-	curtime = timeGetTime() - base;
-
-	return curtime;
-}
-
 long long
 Sys_Microseconds(void)
 {
 	long long microseconds;
-	long long seconds;
 	static long long uSecbase;
 
 	FILETIME ft;
@@ -457,15 +439,40 @@ Sys_Microseconds(void)
 		uSecbase = microseconds - 1001;
 	}
 
+	curtime = (int)((microseconds - uSecbase) / 1000ll);
 	return microseconds - uSecbase;
 }
 
+int
+Sys_Milliseconds(void)
+{
+	curtime = (int)(Sys_Microseconds()/1000ll);
+
+	return curtime;
+}
+
 void
 Sys_Sleep(int msec)
 {
 	Sleep(msec);
 }
 
+void Sys_Nanosleep(int nanosec)
+{
+	HANDLE timer;
+	LARGE_INTEGER li;
+
+	timer = CreateWaitableTimer(NULL, TRUE, NULL);
+
+	// Windows has a max. resolution of 100ns.
+	li.QuadPart = -nanosec / 100;
+
+	SetWaitableTimer(timer, &li, 0, NULL, NULL, FALSE);
+	WaitForSingleObject(timer, INFINITE);
+
+	CloseHandle(timer);
+}
+
 /* ======================================================================= */
 
 static qboolean
@@ -774,7 +781,7 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 		LPSTR lpCmdLine, int nCmdShow)
 {
 	MSG msg;
-	int time, oldtime, newtime;
+	long long oldtime, newtime;
 
 	/* Previous instances do not exist in Win32 */
 	if (hPrevInstance)
@@ -846,7 +853,7 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 	Qcommon_Init(argc, argv);
 
 	/* Save our time */
-	oldtime = Sys_Milliseconds();
+	oldtime = Sys_Microseconds();
 
 	/* The legendary main loop */
 	while (1)
@@ -869,14 +876,11 @@ WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
 			DispatchMessage(&msg);
 		}
 
-		do
-		{
-			newtime = Sys_Milliseconds();
-			time = newtime - oldtime;
-		}
-		while (time < 1);
+		// Throttle the game a little bit
+		Sys_Nanosleep(5000);
 
-		Qcommon_Frame(time);
+		newtime = Sys_Microseconds();
+		Qcommon_Frame(newtime - oldtime);
 		oldtime = newtime;
 	}