From 261063e69e80193ad563e086c515fd6e22e48464 Mon Sep 17 00:00:00 2001
From: Eike Rathke <erack@redhat.com>
Date: Thu, 18 May 2023 23:30:51 +0200
Subject: Eliminate 24h loops in DateTime::operator+=/-=(tools::Time&)

... and repeated Date::operator++/--() that each calculate
lcl_DaysToDate( GetAsNormalizedDays() + 1 )
where Date::AddDays() does it once.

Also, that probably never worked correctly with negative time results >=24h

Change-Id: Ic67aaa3d93e0d6533501d52671acf765e2d9bbdd
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/151984
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins
---
 tools/source/datetime/datetime.cxx | 30 ++++++++++++++++--------------
 1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/tools/source/datetime/datetime.cxx b/tools/source/datetime/datetime.cxx
index 00790ff78dd4..efdb928986c3 100644
--- a/tools/source/datetime/datetime.cxx
+++ b/tools/source/datetime/datetime.cxx
@@ -101,19 +101,20 @@ DateTime& DateTime::operator +=( const tools::Time& rTime )
     sal_uInt16 nHours = aTime.GetHour();
     if ( aTime.GetTime() > 0 )
     {
-        while ( nHours >= 24 )
+        if (nHours >= 24)
         {
-            Date::operator++();
-            nHours -= 24;
+            AddDays( nHours / 24 );
+            nHours %= 24;
+            aTime.SetHour( nHours );
         }
-        aTime.SetHour( nHours );
     }
     else if ( aTime.GetTime() != 0 )
     {
-        while ( nHours >= 24 )
+        if (nHours >= 24)
         {
-            Date::operator--();
-            nHours -= 24;
+            AddDays( -static_cast<sal_Int32>(nHours) / 24 );
+            nHours %= 24;
+            aTime.SetHour( nHours );
         }
         Date::operator--();
         aTime = Time( 24, 0, 0 )+aTime;
@@ -130,19 +131,20 @@ DateTime& DateTime::operator -=( const tools::Time& rTime )
     sal_uInt16 nHours = aTime.GetHour();
     if ( aTime.GetTime() > 0 )
     {
-        while ( nHours >= 24 )
+        if (nHours >= 24)
         {
-            Date::operator++();
-            nHours -= 24;
+            AddDays( nHours / 24 );
+            nHours %= 24;
+            aTime.SetHour( nHours );
         }
-        aTime.SetHour( nHours );
     }
     else if ( aTime.GetTime() != 0 )
     {
-        while ( nHours >= 24 )
+        if (nHours >= 24)
         {
-            Date::operator--();
-            nHours -= 24;
+            AddDays( -static_cast<sal_Int32>(nHours) / 24 );
+            nHours %= 24;
+            aTime.SetHour( nHours );
         }
         Date::operator--();
         aTime = Time( 24, 0, 0 )+aTime;
-- 
cgit