+#define BATTFS_MAX_FILES (1 << (CPU_BITS_PER_CHAR * sizeof(inode_t)))
+
+/* Fwd decl */
+struct BattFsSuper;
+
+/**
+ * Type for disk page addressing.
+ */
+typedef uint16_t pgcnt_t;
+
+/**
+ * Sentinel used to keep trace of unset pages in disk->page_array.
+ */
+#define PAGE_UNSET_SENTINEL ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
+
+/**
+ * Type interface for disk init function.
+ * \return true if all is ok, false otherwise.
+ */
+typedef bool (*disk_open_t) (struct BattFsSuper *d);
+
+/**
+ * Type interface for disk page read function.
+ * \a page is the page address, \a addr the address inside the page,
+ * \a size the lenght to be read.
+ * \return the number of bytes read.
+ */
+typedef size_t (*disk_page_read_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t);
+
+/**
+ * Type interface for disk page write function.
+ * \a page is the page address, \a addr the address inside the page,
+ * \a size the lenght to be written.
+ * \return the number of bytes written.
+ */
+typedef size_t (*disk_page_write_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t);
+
+/**
+ * Type interface for disk page erase function.
+ * \a page is the page address.
+ * \return true if all is ok, false otherwise.
+ */
+typedef bool (*disk_page_erase_t) (struct BattFsSuper *d, pgcnt_t page);
+
+/**
+ * Type interface for disk deinit function.
+ * \return true if all is ok, false otherwise.
+ */
+typedef bool (*disk_close_t) (struct BattFsSuper *d);
+
+
+typedef uint32_t disk_size_t; ///< Type for disk sizes.
+
+/**
+ * Context used to describe a disk.
+ * This context structure will be used to access disk.
+ * Must be initialized by hw memory driver.
+ */
+typedef struct BattFsSuper
+{
+ disk_open_t open; ///< Disk init.
+ disk_page_read_t read; ///< Page read.
+ disk_page_write_t write; ///< Page write.
+ disk_page_erase_t erase; ///< Page erase.
+ disk_close_t close; ///< Disk deinit.
+
+ pgaddr_t page_size; ///< Size of a disk page, in bytes.
+ pgcnt_t page_count; ///< Number of pages on disk.
+
+ /**
+ * Page allocation array.
+ * This array must be allocated somewhere and
+ * must have enough space for page_count elements.
+ * Is used by the filesystem to represent
+ * the entire disk in memory.
+ */
+ pgcnt_t *page_array;
+
+ mark_t free_min; ///< Lowest free page counter.
+ mark_t free_max; ///< Highest free page counter.
+
+ disk_size_t disk_size; ///< Size of the disk, in bytes (page_count * page_size).
+ disk_size_t free_bytes; ///< Free space on the disk.
+
+ /* TODO add other fields. */
+} BattFsSuper;