Add page allocation utility functions

Source/Engine/Platform/Base/PlatformBase.h

@@ -316,6 +316,25 @@ public:
     /// <param name="ptr">A pointer to the memory block to deallocate.</param>
     static void Free(void* ptr) = delete;
 
+    /// <summary>
+    /// Returns the OS's default page size that can be used with AllocatePages.
+    /// </summary>
+    static uint64 GetDefaultPageSize() = delete;
+
+    /// <summary>
+    /// Allocates pages memory block.
+    /// </summary>
+    /// <param name="numPages">The number of pages to allocate.</param>
+    /// <param name="pageSize">The size of single page. Use GetDefaultPageSize() or provide compatible, custom size.</param>
+    /// <returns>The pointer to the allocated pages in memory.</returns>
+    static void* AllocatePages(uint64 numPages, uint64 pageSize) = delete;
+
+    /// <summary>
+    /// Frees allocated pages memory block.
+    /// </summary>
+    /// <param name="ptr">The pointer to the pages to deallocate.</param>
+    static void FreePages(void* ptr) = delete;
+
 public:
 
     /// <summary>

Source/Engine/Platform/Unix/UnixPlatform.cpp

@@ -51,6 +51,25 @@ void UnixPlatform::Free(void* ptr)
     }
 }
 
+uint64 Win32Platform::GetDefaultPageSize()
+{
+    return 16;
+}
+
+void* Win32Platform::AllocatePages(uint64 numPages, uint64 pageSize)
+{
+    const uint64 numBytes = numPages * pageSize;
+
+    // Fallback to malloc
+    return malloc(numBytes);
+}
+
+void Win32Platform::FreePages(void* ptr)
+{
+    // Fallback to free
+    free(ptr);
+}
+
 uint64 UnixPlatform::GetCurrentProcessId()
 {
     return getpid();

Source/Engine/Platform/Unix/UnixPlatform.h

@@ -16,6 +16,9 @@ public:
     // [PlatformBase]
     static void* Allocate(uint64 size, uint64 alignment);
     static void Free(void* ptr);
+    static uint64 GetDefaultPageSize();
+    static void* AllocatePages(uint64 numPages, uint64 pageSize);
+    static void FreePages(void* ptr);
     static uint64 GetCurrentProcessId();
 };
 

Source/Engine/Platform/Win32/Win32Platform.cpp

@@ -298,6 +298,29 @@ void Win32Platform::AtomicStore(int64 volatile* dst, int64 value)
     InterlockedExchange64(dst, value);
 }
 
+uint64 Win32Platform::GetDefaultPageSize()
+{
+    SYSTEM_INFO systemInfo;
+    GetSystemInfo(&systemInfo);
+
+    // Return the page size obtained from system
+    return systemInfo.dwPageSize;
+}
+
+void* Win32Platform::AllocatePages(uint64 numPages, uint64 pageSize)
+{
+    const uint64 numBytes = numPages * pageSize;
+
+    // Use VirtualAlloc to allocate page-aligned memory
+    return VirtualAlloc(nullptr, numBytes, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
+}
+
+void Win32Platform::FreePages(void* ptr)
+{
+    // Free page-aligned memory
+    VirtualFree(ptr, 0, MEM_RELEASE);
+}
+
 bool Win32Platform::Is64BitPlatform()
 {
 #ifdef PLATFORM_64BITS

Source/Engine/Platform/Win32/Win32Platform.h

@@ -43,6 +43,9 @@ public:
     {
         _aligned_free(ptr);
     }
+    static uint64 GetDefaultPageSize();
+    static void* AllocatePages(uint64 numPages, uint64 pageSize);
+    static void FreePages(void* ptr);
     static bool Is64BitPlatform();
     static BatteryInfo GetBatteryInfo();
     static CPUInfo GetCPUInfo();