Added initial superblock definition

Really started working out how the internal structure of the driver
will be organized. There are a few hazy lines between the intended
data structures with the goal of code reuse, so the function boundaries
may end up a bit weird.

lfs.h

@@ -10,22 +10,81 @@
 #include "lfs_config.h"
 #include "lfs_bd.h"
 
-struct lfs_free_list {
-    lfs_ino_t head;
-    lfs_word_t ioff;
-    lfs_word_t icount;
-    lfs_word_t rev;
-};
 
+// Data structures
+typedef struct lfs_free {
+    lfs_disk_struct lfs_disk_free {
+        lfs_ino_t head;
+        lfs_word_t ioff;
+        lfs_word_t icount;
+        lfs_word_t rev;
+    } d;
+} lfs_free_t;
+
+typedef struct lfs_dir {
+    lfs_ino_t dno[2];
+
+    lfs_disk_struct lfs_disk_dir {
+        lfs_word_t rev;
+        lfs_size_t size;
+        lfs_ino_t tail[2];
+        lfs_ino_t parent[2];
+
+        struct lfs_disk_free free;
+    } d;
+} lfs_dir_t; 
+
+typedef struct lfs_entry {
+    lfs_ino_t dir[2];
+    lfs_off_t off;
+
+    lfs_disk_struct lfs_disk_entry {
+        uint16_t type;
+        uint16_t len;
+        union {
+            lfs_disk_struct {
+                lfs_ino_t head;
+                lfs_size_t size;
+                char name[LFS_NAME_MAX];
+            } file;
+            lfs_disk_struct {
+                lfs_ino_t dir[2];
+                char name[LFS_NAME_MAX];
+            } dir;
+            lfs_disk_struct {
+                char magic[4];
+                uint32_t read_size;
+                uint32_t write_size;
+                uint32_t erase_size;
+                uint32_t erase_count;
+            } superblock;
+        } value;
+    } d;
+} lfs_entry_t;
+
+typedef struct lfs_superblock {
+    lfs_disk_struct lfs_disk_superblock {
+        uint32_t rev;
+        uint32_t count;
+        lfs_ino_t root[2];
+        char magic[8];
+        uint32_t block_size;
+        uint32_t block_count;
+    } d;
+} lfs_superblock_t;
+
+// Little filesystem type
 typedef struct lfs {
     lfs_bd_t *bd;
     const struct lfs_bd_ops *ops;
 
-    struct lfs_free_list free;
+    lfs_free_t free;
     struct lfs_bd_info info;
 } lfs_t;
 
+// Functions
 lfs_error_t lfs_create(lfs_t *lfs, lfs_bd_t *bd, const struct lfs_bd_ops *bd_ops);
 lfs_error_t lfs_format(lfs_t *lfs);
+lfs_error_t lfs_mount(lfs_t *lfs);
 
 #endif