From c1d16124e57837ba30abf2147a117fe666a32e0e Mon Sep 17 00:00:00 2001
From: NepDisk <nepdisk@noreply.codeberg.org>
Date: Wed, 15 Oct 2025 16:32:16 -0400
Subject: [PATCH] Port Saturn timestuff branch

Should be better then I_UpdateTime spam
https://github.com/Indev450/SRB2Kart-Saturn/commits/timestuff/
---
 src/d_main.cpp |  4 +---
 src/i_time.c   | 32 ++++++++++++++++++++++++++++++--
 src/i_time.h   |  2 ++
 src/m_fixed.h  | 14 ++++++++++++++
 4 files changed, 47 insertions(+), 5 deletions(-)

diff --git a/src/d_main.cpp b/src/d_main.cpp
index a2d3a9569..187c3dbef 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -1081,9 +1081,7 @@ void D_SRB2Loop(void)
 
 			const boolean lagging = ((deltatics >= 1.0) || hu_stopped);
 
-			I_UpdateTime(cv_timescale.value);
-
-			R_SetTimeFrac(lagging ? FRACUNIT : g_time.timefrac);
+			R_SetTimeFrac(lagging ? FRACUNIT : I_GetTimeFrac());
 		}
 		else
 		{
diff --git a/src/i_time.c b/src/i_time.c
index 3875afd9b..74380e6f7 100644
--- a/src/i_time.c
+++ b/src/i_time.c
@@ -29,6 +29,25 @@ consvar_t cv_timescale = CVAR_INIT ("timescale", "1.0", CV_NETVAR|CV_CHEAT|CV_FL
 static precise_t enterprecise, oldenterprecise;
 static fixed_t entertic, oldentertics;
 static double tictimer;
+static double ticratescaled;
+
+// experiment to prevent timing issues
+// this returns the global time state accounted with how much time has passed
+// since it was last updated
+static void I_GetTimeAndFrac(tic_t *outtics, fixed_t *outfrac)
+{
+	double elapsedseconds;
+
+	elapsedseconds = (double)(I_GetPreciseTime() - oldenterprecise) / I_GetPrecisePrecision();
+
+	double fractional, integral;
+	fractional = modf((tictimer + elapsedseconds) * ticratescaled, &integral);
+
+	if (outtics)
+		*outtics = g_time.time + (tic_t)integral;
+	if (outfrac)
+		*outfrac = DoubleToFixed(fractional);
+}
 
 // A little more than the minimum sleep duration on Windows.
 // May be incorrect for other platforms, but we don't currently have a way to
@@ -42,7 +61,16 @@ static double tictimer;
 
 tic_t I_GetTime(void)
 {
-	return g_time.time;
+	tic_t tic;
+	I_GetTimeAndFrac(&tic, NULL);
+	return tic;
+}
+
+fixed_t I_GetTimeFrac(void)
+{
+	fixed_t frac;
+	I_GetTimeAndFrac(NULL, &frac);
+	return frac;
 }
 
 void I_InitializeTime(void)
@@ -53,6 +81,7 @@ void I_InitializeTime(void)
 	enterprecise = 0;
 	oldenterprecise = 0;
 	tictimer = 0.0;
+	ticratescaled = 1.0;
 
 	CV_RegisterVar(&cv_timescale);
 
@@ -63,7 +92,6 @@ void I_InitializeTime(void)
 
 void I_UpdateTime(fixed_t timescale)
 {
-	double ticratescaled;
 	double elapsedseconds;
 	tic_t realtics;
 
diff --git a/src/i_time.h b/src/i_time.h
index 141fbcb2d..3bf59b589 100644
--- a/src/i_time.h
+++ b/src/i_time.h
@@ -34,6 +34,8 @@ extern consvar_t cv_timescale;
 */
 tic_t I_GetTime(void);
 
+fixed_t I_GetTimeFrac(void);
+
 /**	\brief  Initializes timing system.
 */
 void I_InitializeTime(void);
diff --git a/src/m_fixed.h b/src/m_fixed.h
index 2080c396f..5f2aa864d 100644
--- a/src/m_fixed.h
+++ b/src/m_fixed.h
@@ -70,6 +70,20 @@ FUNCMATH FUNCINLINE static ATTRINLINE INT64 FloatToFixed64(float f)
 	return (INT64)(f * FRACUNIT);
 }
 
+/*!
+ * \brief convert fixed_t into double-precision floating number
+ */
+
+FUNCMATH FUNCINLINE static ATTRINLINE double FixedToDouble(fixed_t x)
+{
+	return x / (double)FRACUNIT;
+}
+
+FUNCMATH FUNCINLINE static ATTRINLINE fixed_t DoubleToFixed(double f)
+{
+	return (fixed_t)(f * FRACUNIT);
+}
+
 // for backwards compat
 #define FIXED_TO_FLOAT(x) FixedToFloat(x) // (((float)(x)) / ((float)FRACUNIT))
 #define FLOAT_TO_FIXED(f) FloatToFixed(f) // (fixed_t)((f) * ((float)FRACUNIT))