From ae790f5a9e69b22c684a8b66427ba7017f39d5d8 Mon Sep 17 00:00:00 2001
From: Patedam <pgillen.pro@gmail.com>
Date: Sun, 9 Aug 2026 11:32:06 -0400
Subject: [PATCH] moved delta time computation to the HAL

---
 Juliet/include/Core/HAL/OS/OS.h          |  3 +++
 Juliet/src/Core/HAL/OS/OS.cpp            | 22 ++++++++++++++++++++++
 Juliet/src/Core/HAL/OS/OS_Private.h      |  3 ++-
 Juliet/src/Core/HAL/OS/Win32/Win32OS.cpp | 20 ++++++++++++++++++++
 Juliet/src/Engine/Engine.cpp             | 24 +++---------------------
 5 files changed, 50 insertions(+), 22 deletions(-)

diff --git a/Juliet/include/Core/HAL/OS/OS.h b/Juliet/include/Core/HAL/OS/OS.h
index fe4d30d..5c0eff6 100644
--- a/Juliet/include/Core/HAL/OS/OS.h
+++ b/Juliet/include/Core/HAL/OS/OS.h
@@ -34,6 +34,9 @@ namespace Juliet
     namespace Time
     {
         uint64 Timestamp();
+        void   ComputeDeltaTime();
+        float  GetDeltaTime();
+        uint64 GetFrameNumber();
     } // namespace Time
 
     namespace Debug
diff --git a/Juliet/src/Core/HAL/OS/OS.cpp b/Juliet/src/Core/HAL/OS/OS.cpp
index 128ddb7..dc1905e 100644
--- a/Juliet/src/Core/HAL/OS/OS.cpp
+++ b/Juliet/src/Core/HAL/OS/OS.cpp
@@ -23,10 +23,32 @@ namespace Juliet
 
     namespace Time
     {
+        namespace
+        {
+            float  DeltaTime = 0.0f;
+            uint64 Frame     = 0;
+        } // namespace
+
         uint64 Timestamp()
         {
             return Internal::OS_Timestamp();
         }
+
+        void ComputeDeltaTime()
+        {
+            DeltaTime = Internal::OS_ComputeDeltaTime();
+            ++Frame;
+        }
+
+        float GetDeltaTime()
+        {
+            return DeltaTime;
+        }
+
+        uint64 GetFrameNumber()
+        {
+            return Frame;
+        }
     } // namespace Time
 
     namespace Debug
diff --git a/Juliet/src/Core/HAL/OS/OS_Private.h b/Juliet/src/Core/HAL/OS/OS_Private.h
index 201a320..d16e6ed 100644
--- a/Juliet/src/Core/HAL/OS/OS_Private.h
+++ b/Juliet/src/Core/HAL/OS/OS_Private.h
@@ -17,7 +17,8 @@ namespace Juliet
     namespace Time::Internal
     {
         uint64 OS_Timestamp();
-    }
+        float  OS_ComputeDeltaTime();
+    } // namespace Time::Internal
 
     namespace Internal
     {
diff --git a/Juliet/src/Core/HAL/OS/Win32/Win32OS.cpp b/Juliet/src/Core/HAL/OS/Win32/Win32OS.cpp
index 57bb574..23723ea 100644
--- a/Juliet/src/Core/HAL/OS/Win32/Win32OS.cpp
+++ b/Juliet/src/Core/HAL/OS/Win32/Win32OS.cpp
@@ -54,6 +54,26 @@ namespace Juliet
 
             return (static_cast<uint64>(ft.dwHighDateTime) << 32) + ft.dwLowDateTime;
         }
+
+        float OS_ComputeDeltaTime()
+        {
+            static LARGE_INTEGER frequency = {};
+            static LARGE_INTEGER lastTime  = {};
+            if (frequency.QuadPart == 0)
+            {
+                QueryPerformanceFrequency(&frequency);
+                QueryPerformanceCounter(&lastTime);
+            }
+
+            LARGE_INTEGER currentTime;
+            QueryPerformanceCounter(&currentTime);
+            const float deltaTime =
+                static_cast<float>(currentTime.QuadPart - lastTime.QuadPart) / static_cast<float>(frequency.QuadPart);
+            lastTime = currentTime;
+
+            return deltaTime;
+        }
+
     } // namespace Time::Internal
 
     namespace Debug::Internal
diff --git a/Juliet/src/Engine/Engine.cpp b/Juliet/src/Engine/Engine.cpp
index 59c690d..b7d5ef6 100644
--- a/Juliet/src/Engine/Engine.cpp
+++ b/Juliet/src/Engine/Engine.cpp
@@ -3,6 +3,7 @@
 #include <Core/Common/CoreUtils.h>
 #include <Core/HAL/Event/SystemEvent.h>
 #include <Core/HAL/Filesystem/Filesystem_Private.h>
+#include <Core/HAL/OS/OS.h>
 #include <Core/JulietInit.h>
 #include <Core/Logging/LogManager.h>
 #include <Core/Memory/MemoryArena.h>
@@ -19,14 +20,6 @@
 #include <imgui.h>
 #endif
 
-// TODO Move to os hal for query perf
-#ifdef _WIN32
-#ifndef WIN32_LEAN_AND_MEAN
-#define WIN32_LEAN_AND_MEAN
-#endif
-#include <Windows.h>
-#endif
-
 namespace Juliet
 {
 #if JULIET_DEBUG
@@ -219,20 +212,9 @@ namespace Juliet
             ImGuiRenderer_NewFrame();
 #endif
 
-            // TODO : Move to os side as it is win32 only
-            static LARGE_INTEGER frequency = {};
-            static LARGE_INTEGER lastTime  = {};
-            if (frequency.QuadPart == 0)
-            {
-                QueryPerformanceFrequency(&frequency);
-                QueryPerformanceCounter(&lastTime);
-            }
+            Time::ComputeDeltaTime();
 
-            LARGE_INTEGER currentTime;
-            QueryPerformanceCounter(&currentTime);
-            float deltaTime =
-                static_cast<float>(currentTime.QuadPart - lastTime.QuadPart) / static_cast<float>(frequency.QuadPart);
-            lastTime = currentTime;
+            const float deltaTime = Time::GetDeltaTime();
 
             Events_NewFrame(deltaTime);