Add BytePointer to help with pointer conversions

This behaves mostly like a pointer, but pointer maths works in bytes,
not the native object size.

It avoids casting to char* and back when doing byte-based pointer math,
making the code easier to read.

Change-Id: I6a8681a398345f0c7d419a2cfe7244d972ffa62f
Reviewed-on: https://review.haiku-os.org/c/1086
Reviewed-by: waddlesplash <[email protected]>

headers/private/shared/BytePointer.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2019, Adrien Destugues, [email protected].
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef _BYTE_POINTER_H
+#define _BYTE_POINTER_H
+
+
+#include <stdlib.h>
+
+
+// Behaves like a char* pointer, but -> and & return the right pointed type.
+// Assumes the offsets passed to + and += maintain the alignment for the type.
+template<class T> struct BytePointer {
+	char* address;
+
+	BytePointer(void* base) { address = (char*)base; }
+
+	T* operator&() { return reinterpret_cast<T*>(address); }
+	T* operator->() { return reinterpret_cast<T*>(address); }
+	void operator+=(size_t offset) { address += offset; }
+	char* operator+(size_t offset) const { return address + offset; }
+};
+
+
+#endif