* \author Francesco Sacchi <batt@develer.com>
*
* \brief BattFS: a filesystem for embedded platforms (interface).
+ * TODO: Add detailed filesystem description.
*/
#ifndef FS_BATTFS_H
#define FS_BATTFS_H
#include <cfg/compiler.h> // uintXX_t; STATIC_ASSERT
+#include <cpu/types.h> // CPU_BITS_PER_CHAR
+#include <algo/rotating_hash.h>
+
+typedef uint16_t fill_t;
+typedef fill_t pgaddr_t;
+typedef uint16_t pgoff_t;
+typedef pgoff_t mark_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 alignment.
+ * \note fields order is chosen to comply
+ * with CPU alignment.
*/
typedef struct BattFsPageHeader
{
- uint16_t filled; ///< filled bytes in page.
- uint16_t page_off; ///< Page offset inside file.
- uint8_t inode; ///< File inode (file identifier).
- uint8_t seqnum; ///< bit[1:0]: Page sequence number; bit[7:2] unused for now, must be set to 1.
- uint16_t crc; ///< CRC of the page header.
+ 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.
+
+ /**
+ * 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);
+
+
+/**
+ * Mark for valid pages.
+ * Simply set to 1 all field bits.
+ */
+#define MARK_PAGE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(mark_t))) - 1)
+
+/**
+ * Max number of files.
+ */
+#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->pag_array.
+ */
+#define PAGE_UNSET_SENTINEL ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
-STATIC_ASSERT(sizeof(BattFsPageHeader) == 8);
+/**
+ * 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);
/**
- * Reset page sequence number of struct \a m to default value (0xFF).
+ * 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.
*/
-#define RESET_SEQ(m) ((m).seqnum = 0xFF)
+typedef size_t (*disk_page_write_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t);
/**
- * Get page sequence number from struct \a m.
+ * Type interface for disk page erase function.
+ * \a page is the page address.
+ * \return true if all is ok, false otherwise.
*/
-#define SEQ(m) ((m).seqnum & 0x03)
+typedef bool (*disk_page_erase_t) (struct BattFsSuper *d, pgcnt_t page);
/**
- * Set sequence number of struct \a m to \a d.
+ * Type interface for disk deinit function.
+ * \return true if all is ok, false otherwise.
*/
-#define SET_SEQ(m, d) ((m).seqnum = ((m).seqnum & 0xFC) | ((d) & 0x03))
+typedef bool (*disk_close_t) (struct BattFsSuper *d);
+
+
+typedef uint32_t disk_size_t; ///< Type for disk sizes.
/**
- * Increment sequence number of struct \a m.
+ * Context used to describe a disk.
+ * This context structure will be used to access disk.
+ * Must be initialized by hw memory driver.
*/
-#define INC_SEQ(m) SET_SEQ((m), SEQ(m) + 1)
+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 min_free; ///< Lowest sequence number of free page
+ mark_t max_free; ///< Highest sequence number of free page
+
+ 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;
+bool battfs_init(struct BattFsSuper *d);
#endif /* FS_BATTFS_H */
projects / bertos.git / blobdiff