typedef uint16_t fill_t;
typedef fill_t pgaddr_t;
typedef uint16_t pgoff_t;
-typedef pgoff_t mark_t;
+typedef uint32_t mark_t;
+typedef uint8_t mark_roll_t;
typedef uint8_t inode_t;
typedef uint8_t seq_t;
typedef rotating_t fcs_t;
/**
- * BattFS page header.
- * \note fields order is chosen to comply
- * with CPU alignment.
+ * Size required for free block allocation is at least 1 bit more
+ * than page addressing.
+ */
+STATIC_ASSERT(sizeof(mark_t) > sizeof(pgaddr_t));
+
+/**
+ * BattFS page header, used to represent a page
+ * header in memory.
+ * To see how this is stored on disk:
+ * \see battfs_to_disk
+ * \see disk_to_battfs
*/
typedef struct BattFsPageHeader
{
inode_t inode; ///< File inode (file identifier).
seq_t seq; ///< Page sequence number.
- mark_t mark; ///< Marker used to keep trace of free/used pages.
- pgoff_t pgoff; ///< Page offset inside file.
fill_t fill; ///< Filled bytes in page.
- uint16_t rfu; ///< Reserved for future use, 0xFFFF for now.
+ pgoff_t pgoff; ///< Page offset inside file.
+ mark_t mark; ///< Marker used to keep trace of free/used pages.
+
+ /**
+ * FCS (Frame Check Sequence) of the page header once the page
+ * as been marked as free.
+ */
+ fcs_t fcs_free;
/**
* FCS (Frame Check Sequence) of the page header.
- * \note This field must be the last one!
- * This is needed because if the page is only partially
- * written, we can use this to detect it.
*/
fcs_t fcs;
} BattFsPageHeader;
-/* Ensure structure has no padding added */
-STATIC_ASSERT(sizeof(BattFsPageHeader) == 12);
+/**
+ * Size of the header once saved on disk.
+ * \see battfs_to_disk
+ * \see disk_to_battfs
+ */
+#define BATTFS_HEADER_LEN 13
/**
- * Mark for valid pages.
+ * Marks for valid pages.
* Simply set to 1 all field bits.
+ * \{
+ */
+#define MARK_PAGE_VALID ((1LL << (CPU_BITS_PER_CHAR * sizeof(mark_t))) - 1)
+#define FCS_FREE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(fcs_t))) - 1)
+/* \} */
+
+
+/**
+ * Half-size of free page marker.
+ * Used to keep trace of free marker wrap-arounds.
+ */
+#define MARK_HALF_SIZE (1 << (CPU_BITS_PER_CHAR * sizeof(pgaddr_t) + 1))
+
+/**
+ * Maximum page address.
*/
-#define MARK_PAGE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(mark_t))) - 1)
+#define MAX_PAGE_ADDR ((1 << (CPU_BITS_PER_CHAR * sizeof(pgaddr_t))) - 1)
/**
* Max number of files.
typedef uint16_t pgcnt_t;
/**
- * Sentinel used to keep trace of unset pages in disk->pag_array.
+ * 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)
*/
pgcnt_t *page_array;
- mark_t min_free; ///< Lowest sequence number of free page
- mark_t max_free; ///< Highest sequence number of free page
+ 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.