From b98be0c2e7f2a333e6663eebfa90748d3f7ffe91 Mon Sep 17 00:00:00 2001
From: toxieainc <toxie@ainc.de>
Date: Mon, 11 Jul 2022 18:47:13 +0200
Subject: [PATCH] optimize ReadRegister, as localtime (at least on
 MSVC/Windows) is significantly showing up in profiling

e.g. in SW Trilogy

caches localtime until time changes (i.e. limits calls to 1/sec)
---
 Src/Model3/RTC72421.cpp | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/Src/Model3/RTC72421.cpp b/Src/Model3/RTC72421.cpp
index 7cc2c27..d5490ef 100644
--- a/Src/Model3/RTC72421.cpp
+++ b/Src/Model3/RTC72421.cpp
@@ -33,7 +33,7 @@
 
 #include "RTC72421.h"
 
-#include <time.h>
+#include <ctime>
 #include "Supermodel.h"
 
 
@@ -43,11 +43,16 @@
 
 UINT8 CRTC72421::ReadRegister(unsigned reg)
 {
-	time_t 		currentTime;
-	struct tm	*Time;
+	static time_t oldTime{0};
+	time_t currentTime;
+	static struct tm *Time;
 
 	time(&currentTime);
-	Time = localtime(&currentTime);
+	if (currentTime != oldTime)
+	{
+		Time = localtime(&currentTime);
+		oldTime = currentTime;
+	}
 
 	switch (reg&0xF)
 	{