From 94b249172a4bb2f0d39f7b83371bf10f878b27fb Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@users.noreply.github.com>
Date: Sun, 9 Oct 2022 14:52:08 +0200
Subject: [PATCH] - normalize the timer with the app start, not the epoch.

This ensures smaller values and less wraparounds with integer values in scripts.
---
 src/common/utility/i_time.cpp | 18 +++++++++++++++---
 src/common/utility/i_time.h   |  2 ++
 src/d_main.cpp                |  1 +
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/common/utility/i_time.cpp b/src/common/utility/i_time.cpp
index 4f2ac96cb0..51ad0359dd 100644
--- a/src/common/utility/i_time.cpp
+++ b/src/common/utility/i_time.cpp
@@ -44,6 +44,7 @@
 //
 //==========================================================================
 
+static uint64_t StartupTimeNS;
 static uint64_t FirstFrameStartTime;
 static uint64_t CurrentFrameStartTime;
 static uint64_t FreezeTime;
@@ -52,11 +53,22 @@ int GameTicRate = 35;	// make sure it is not 0, even if the client doesn't set i
 
 double TimeScale = 1.0;
 
-static uint64_t GetClockTimeNS()
+static uint64_t GetTimePoint()
 {
 	using namespace std::chrono;
-	if (TimeScale == 1.0) return (uint64_t)(duration_cast<nanoseconds>(steady_clock::now().time_since_epoch()).count());
-	else return (uint64_t)((duration_cast<microseconds>(steady_clock::now().time_since_epoch()).count()) * (uint64_t)(TimeScale * 1000));
+	return (uint64_t)(duration_cast<nanoseconds>(steady_clock::now().time_since_epoch()).count());
+}
+
+void I_InitTime()
+{
+	StartupTimeNS = GetTimePoint();
+}
+
+static uint64_t GetClockTimeNS()
+{
+	auto tp = GetTimePoint() - StartupTimeNS;
+	if (TimeScale == 1.0) return tp;
+	else return tp / 1000 * TimeScale * 1000;
 }
 
 static uint64_t MSToNS(unsigned int ms)
diff --git a/src/common/utility/i_time.h b/src/common/utility/i_time.h
index d9501ea96a..e5d3d5c8df 100644
--- a/src/common/utility/i_time.h
+++ b/src/common/utility/i_time.h
@@ -5,6 +5,8 @@
 extern int GameTicRate;
 extern double TimeScale;
 
+void I_InitTime();
+
 // Called by D_DoomLoop, sets the time for the current frame
 void I_SetFrameTime();
 
diff --git a/src/d_main.cpp b/src/d_main.cpp
index 0aff8c3562..7d754e65c1 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -3688,6 +3688,7 @@ int GameMain()
 {
 	int ret = 0;
 	GameTicRate = TICRATE;
+	I_InitTime();
 
 	ConsoleCallbacks cb = {
 		D_UserInfoChanged,