Clean and document header files.

- Add missing doc comments to header files
- Move allocate_kernel_args to main.cpp
- Split functions out into pointer_manipulation.h

src/boot/loader.h

@@ -1,15 +1,22 @@
+/// \file loader.h
+/// Definitions for loading the kernel into memory
 #pragma once
 
 namespace boot {
 namespace loader {
 
+/// Structure to hold information about loaded binary image.
 struct loaded_elf
 {
-	void *data;
-	uintptr_t vaddr;
-	uintptr_t entrypoint;
+	void *data;           ///< Start of the kernel in memory
+	uintptr_t vaddr;      ///< Virtual address to map to
+	uintptr_t entrypoint; ///< (Virtual) address of the kernel entrypoint
 };
 
+/// Parse and load an ELF file in memory into a loaded image.
+/// \arg data  The start of the ELF file in memory
+/// \arg size  The size of the ELF file in memory
+/// \returns   A `loaded_elf` structure defining the loaded image
 loaded_elf load(const void *data, size_t size, uefi::boot_services *bs);
 
 } // namespace loader