From 0e2abe7eb5275063eb55f2ab9405ada6d4386bb1 Mon Sep 17 00:00:00 2001
From: Dibyamartanda Samanta <dibyaxp@noreply.codingworkshop.git>
Date: Wed, 7 Aug 2024 14:47:04 +0200
Subject: [PATCH] [NTOSKRNL:CC] Add CalculatePageCount Template

Added CalculatePageCount Template function to calculate total pagecount from file offset and length
---
 NTOSKRNL/CC/ccinternal.hpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/NTOSKRNL/CC/ccinternal.hpp b/NTOSKRNL/CC/ccinternal.hpp
index 9d3e57c..94a0e72 100644
--- a/NTOSKRNL/CC/ccinternal.hpp
+++ b/NTOSKRNL/CC/ccinternal.hpp
@@ -144,3 +144,16 @@ private:
         }
     }
 };
+
+template<typename T>
+ULONG CalculatePageCount(T Length, LARGE_INTEGER FileOffset) {
+    constexpr ULONG PAGE_OFFSET = 0xFFF;  // 4095 (mask for the lower 12 bits)
+    constexpr ULONG PAGE_SHIFT = 12;      // Shift by 12 bits for 4KB pages
+
+    // Calculate the page count
+    ULONG pageCount = (Length >> PAGE_SHIFT) + 
+                      ((FileOffset.LowPart & PAGE_OFFSET) + 4095 + (Length & PAGE_OFFSET)) >> PAGE_SHIFT;
+
+    return pageCount;
+}
+