Parse ELF and load kernel, specify mem types

* Very bare-bones ELF parsing to load the kernel
* Custom memory type values for allocated memory

src/boot/memory.h

@@ -9,6 +9,16 @@ namespace memory {
 
 constexpr size_t page_size = 0x1000;
 
+constexpr uefi::memory_type args_type   = static_cast<uefi::memory_type>(0x80000000);
+constexpr uefi::memory_type module_type = static_cast<uefi::memory_type>(0x80000001);
+constexpr uefi::memory_type kernel_type = static_cast<uefi::memory_type>(0x80000002);
+constexpr uefi::memory_type table_type  = static_cast<uefi::memory_type>(0x80000003);
+
+template <typename T, typename S>
+static T* offset_ptr(S* input, ptrdiff_t offset) {
+	return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(input) + offset);
+}
+
 inline constexpr size_t bytes_to_pages(size_t bytes) {
 	return ((bytes - 1) / page_size) + 1;
 }
@@ -21,20 +31,52 @@ void mark_pointer_fixup(void **p);
 
 kernel::args::header * allocate_args_structure(uefi::boot_services *bs, size_t max_modules);
 
-/*
-extern const EFI_MEMORY_TYPE memtype_kernel;
-extern const EFI_MEMORY_TYPE memtype_data;
-extern const EFI_MEMORY_TYPE memtype_initrd;
-extern const EFI_MEMORY_TYPE memtype_scratch;
+template <typename T>
+class offset_iterator
+{
+	T* m_t;
+	size_t m_off;
+public:
+	offset_iterator(T* t, size_t offset=0) : m_t(t), m_off(offset) {}
 
-struct memory_map {
+	T* operator++() { m_t = offset_ptr<T>(m_t, m_off); return m_t; }
+	T* operator++(int) { T* tmp = m_t; operator++(); return tmp; }
+	bool operator==(T* p) { return p == m_t; }
+
+	T* operator*() const { return m_t; }
+	operator T*() const { return m_t; }
+	T* operator->() const { return m_t; }
+};
+
+struct efi_mem_map {
 	size_t length;
 	size_t size;
 	size_t key;
 	uint32_t version;
-	EFI_MEMORY_DESCRIPTOR *entries;
+	uefi::memory_descriptor *entries;
+
+	inline size_t num_entries() const { return length / size; }
+
+	inline uefi::memory_descriptor * operator[](size_t i) {
+		size_t offset = i * size;
+		if (offset > length) return nullptr;
+		return offset_ptr<uefi::memory_descriptor>(entries, offset);
+	}
+
+	offset_iterator<uefi::memory_descriptor> begin() { return offset_iterator<uefi::memory_descriptor>(entries, size); }
+	offset_iterator<uefi::memory_descriptor> end() { return offset_ptr<uefi::memory_descriptor>(entries, length); }
 };
 
+efi_mem_map get_mappings(uefi::boot_services *bs);
+
+enum class memory_type
+{
+	free,
+	loader_used,
+	system_used
+};
+
+/*
 EFI_STATUS memory_get_map_length(EFI_BOOT_SERVICES *bootsvc, size_t *size);
 EFI_STATUS memory_get_map(EFI_BOOT_SERVICES *bootsvc, struct memory_map *map);
 EFI_STATUS memory_dump_map(struct memory_map *map);