X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=fs%2Fbattfs.h;h=c155b61ee2e17a11e657cc550930d1267bb06499;hb=0d9fb160fec7a9e4d1b75a877f133b32735343d1;hp=0449d4f1a50ebff4f4b62eebfb826c37aaaf0932;hpb=71ef544fea9e991379181432011abb47166fec7b;p=bertos.git diff --git a/fs/battfs.h b/fs/battfs.h index 0449d4f1..c155b61e 100644 --- a/fs/battfs.h +++ b/fs/battfs.h @@ -35,47 +35,186 @@ * \author Francesco Sacchi * * \brief BattFS: a filesystem for embedded platforms (interface). + * TODO: Add detailed filesystem description. */ #ifndef FS_BATTFS_H #define FS_BATTFS_H #include // uintXX_t; STATIC_ASSERT +#include // CPU_BITS_PER_CHAR +#include + +typedef uint16_t fill_t; +typedef fill_t pgaddr_t; +typedef uint16_t pgoff_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; + +/** + * 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. - * \note fields order is chosen to comply with alignment. + * 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 { - 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. + fill_t fill; ///< Filled bytes in page. + 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. + */ + fcs_t fcs; } BattFsPageHeader; -STATIC_ASSERT(sizeof(BattFsPageHeader) == 8); +/** + * Size of the header once saved on disk. + * \see battfs_to_disk + * \see disk_to_battfs + */ +#define BATTFS_HEADER_LEN 12 + +/** + * Marks for valid pages. + * Simply set to 1 all field bits. + * \{ + */ +#define MARK_PAGE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(pgaddr_t) + 1)) - 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 MAX_PAGE_ADDR ((1 << (CPU_BITS_PER_CHAR * sizeof(pgaddr_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; /** - * Reset page sequence number of struct \a m to default value (0xFF). + * Sentinel used to keep trace of unset pages in disk->page_array. */ -#define RESET_SEQ(m) ((m).seqnum = 0xFF) +#define PAGE_UNSET_SENTINEL ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1) /** - * Get page sequence number from struct \a m. + * Type interface for disk init function. + * \return true if all is ok, false otherwise. */ -#define SEQ(m) ((m).seqnum & 0x03) +typedef bool (*disk_open_t) (struct BattFsSuper *d); /** - * Set sequence number of struct \a m to \a 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. */ -#define SET_SEQ(m, d) ((m).seqnum = ((m).seqnum & 0xFC) | ((d) & 0x03)) +typedef size_t (*disk_page_read_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t); /** - * Increment sequence number of struct \a m. + * 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 INC_SEQ(m) SET_SEQ((m), SEQ(m) + 1) +typedef size_t (*disk_page_write_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, const 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; + + /** + * Lowest free page counter. + * This is the counter of the first availble free page. + */ + mark_t free_start; + + /** + * Highest free page counter. + * This value is the next to be used to mark a block as free. + */ + mark_t free_next; + + 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); +bool battfs_writeTestBlock(struct BattFsSuper *disk, pgcnt_t page, inode_t inode, seq_t seq, fill_t fill, pgoff_t pgoff, mark_t mark); #endif /* FS_BATTFS_H */