From c5c45a1fb0476444eb1c576e9e160d0fd30fa60c Mon Sep 17 00:00:00 2001
From: Hannu Hanhi <hhanhipublic@gmail.com>
Date: Sat, 2 May 2020 23:06:01 +0300
Subject: [PATCH] Implement I_GetTimeMicros without affecting I_GetTime
 behaviour details

---
 src/sdl/i_system.c | 49 ++++++++++++++++++++--------------------------
 1 file changed, 21 insertions(+), 28 deletions(-)

diff --git a/src/sdl/i_system.c b/src/sdl/i_system.c
index 9d63225cb..426904c63 100644
--- a/src/sdl/i_system.c
+++ b/src/sdl/i_system.c
@@ -2060,12 +2060,11 @@ static p_timeGetTime pfntimeGetTime = NULL;
 // but lower precision on Windows NT
 // ---------
 
-DWORD TimeFunction(boolean microseconds)
+DWORD TimeFunction(int requested_frequency)
 {
 	DWORD newtics = 0;
-	int multiplier = 1;
-
-	if (microseconds) multiplier = 1000;
+	// this var acts as a multiplier if sub-millisecond precision is asked but is not available
+	int excess_frequency = requested_frequency / 1000;
 
 	if (!starttickcount) // high precision timer
 	{
@@ -2085,7 +2084,7 @@ DWORD TimeFunction(boolean microseconds)
 
 		if (frequency.LowPart && QueryPerformanceCounter(&currtime))
 		{
-			newtics = (INT32)((currtime.QuadPart - basetime.QuadPart) * 1000 * multiplier
+			newtics = (INT32)((currtime.QuadPart - basetime.QuadPart) * requested_frequency
 				/ frequency.QuadPart);
 		}
 		else if (pfntimeGetTime)
@@ -2093,11 +2092,19 @@ DWORD TimeFunction(boolean microseconds)
 			currtime.LowPart = pfntimeGetTime();
 			if (!basetime.LowPart)
 				basetime.LowPart = currtime.LowPart;
-			newtics = currtime.LowPart - basetime.LowPart;
+			if (requested_frequency > 1000)
+				newtics = currtime.LowPart - basetime.LowPart * excess_frequency;
+			else
+				newtics = (currtime.LowPart - basetime.LowPart)/(1000/requested_frequency);
 		}
 	}
 	else
-		newtics = (GetTickCount() - starttickcount) * multiplier;
+	{
+		if (requested_frequency > 1000)
+			newtics = (GetTickCount() - starttickcount) * excess_frequency;
+		else
+			newtics = (GetTickCount() - starttickcount)/(1000/requested_frequency);
+	}
 
 	return newtics;
 }
@@ -2119,8 +2126,9 @@ static void I_ShutdownTimer(void)
 // I_GetTime
 // returns time in 1/TICRATE second tics
 //
-/*
-tic_t I_GetTime (void)
+
+// millisecond precision only
+int TimeFunction(int requested_frequency)
 {
 	static Uint64 basetime = 0;
 		   Uint64 ticks = SDL_GetTicks();
@@ -2130,37 +2138,22 @@ tic_t I_GetTime (void)
 
 	ticks -= basetime;
 
-	ticks = (ticks*TICRATE);
+	ticks = (ticks*requested_frequency);
 
 	ticks = (ticks/1000);
 
-	return (tic_t)ticks;
-}
-*/
-int TimeFunction(boolean microseconds)// this cant actually do microseconds so it fakes it
-{
-	static Uint64 basetime = 0;
-		   Uint64 ticks = SDL_GetTicks();
-
-	if (!basetime)
-		basetime = ticks;
-
-	ticks -= basetime;
-	
-	return microseconds ? ticks * 1000 : ticks;
+	return ticks;
 }
 #endif
 
 tic_t I_GetTime(void)
 {
-	//return TimeFunction(false) / (1000/NEWTICRATE);
-	// how about this
-	return (TimeFunction(false) * NEWTICRATE) / 1000;
+	return TimeFunction(NEWTICRATE);
 }
 
 int I_GetTimeMicros(void)
 {
-	return TimeFunction(true);
+	return TimeFunction(1000000);
 }
 
 //