Memory: Factorize virtual memory reservation/allocation code in function

Utilities/VirtualMemory.cpp

@@ -0,0 +1,41 @@
+#include "stdafx.h"
+#include "VirtualMemory.h"
+#ifdef _WIN32
+#include <Windows.h>
+#else
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/types.h>
+#endif
+
+namespace memory_helper
+{
+	void* reserve_memory(size_t size)
+	{
+#ifdef _WIN32
+		return VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_NOACCESS);
+#else
+		return mmap(nullptr, size, PROT_NONE, MAP_ANON | MAP_PRIVATE, -1, 0);
+#endif
+	}
+
+	void commit_page_memory(void* pointer, size_t page_size)
+	{
+#ifdef _WIN32
+		VirtualAlloc((u8*)pointer, page_size, MEM_COMMIT, PAGE_READWRITE);
+#else
+		mprotect((u8*)pointer, page_size, PROT_READ | PROT_WRITE);
+#endif
+	}
+
+	void free_reserved_memory(void* pointer, size_t size)
+	{
+#ifdef _WIN32
+		VirtualFree(pointer, 0, MEM_RELEASE);
+#else
+		munmap(pointer, size);
+#endif
+	}
+}

Utilities/VirtualMemory.h

@@ -0,0 +1,22 @@
+#pragma once
+
+namespace memory_helper
+{
+	/**
+	* Reserve size bytes of virtual memory and returns it.
+	* The memory should be commited before usage.
+	*/
+	void* reserve_memory(size_t size);
+
+	/**
+	* Commit page_size bytes of virtual memory starting at pointer.
+	* That is, bake reserved memory with physical memory.
+	* pointer should belong to a range of reserved memory.
+	*/
+	void commit_page_memory(void* pointer, size_t page_size);
+
+	/**
+	* Free memory alloced via reserve_memory.
+	*/
+	void free_reserved_memory(void* pointer, size_t size);
+}