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29 * Copyright 2007 Develer S.r.l. (http://www.develer.com/)
35 * \author Francesco Sacchi <batt@develer.com>
37 * \brief BattFS: a filesystem for embedded platforms (interface).
38 * TODO: Add detailed filesystem description.
44 #include <cfg/compiler.h> // uintXX_t; STATIC_ASSERT
45 #include <cpu/types.h> // CPU_BITS_PER_CHAR
46 #include <algo/rotating_hash.h>
47 #include <mware/list.h>
48 #include <kern/kfile.h>
50 typedef uint16_t fill_t; ///< Type for keeping trace of space filled inside a page
51 typedef fill_t pgaddr_t; ///< Type for addressing space inside a page
52 typedef uint16_t pgcnt_t; ///< Type for counting pages on disk
53 typedef pgcnt_t pgoff_t; ///< Type for counting pages inside a file
54 typedef uint32_t mark_t; ///< Type for marking pages as free
55 typedef uint8_t inode_t; ///< Type for file inodes
56 typedef uint8_t seq_t; ///< Type for page seq number
57 typedef rotating_t fcs_t; ///< Type for header FCS.
60 * Size required for free block allocation is at least 1 bit more
61 * than page addressing.
63 STATIC_ASSERT(sizeof(mark_t) > sizeof(pgcnt_t));
66 * BattFS page header, used to represent a page
68 * To see how this is stored on disk:
72 typedef struct BattFsPageHeader
74 inode_t inode; ///< File inode (file identifier).
75 seq_t seq; ///< Page sequence number.
76 fill_t fill; ///< Filled bytes in page.
77 pgoff_t pgoff; ///< Page offset inside file.
78 mark_t mark; ///< Marker used to keep trace of free/used pages.
81 * FCS (Frame Check Sequence) of the page header once the page
82 * as been marked as free.
87 * FCS (Frame Check Sequence) of the page header.
93 * Size of the header once saved on disk.
97 #define BATTFS_HEADER_LEN 12
100 * Marks for valid pages.
101 * Simply set to 1 all field bits.
104 #define MARK_PAGE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t) + 1)) - 1)
105 #define FCS_FREE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(fcs_t))) - 1)
110 * Half-size of free page marker.
111 * Used to keep trace of free marker wrap-arounds.
113 #define MARK_HALF_SIZE (1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t) + 1))
116 * Maximum page address.
118 #define MAX_PAGE_ADDR ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
121 * Max number of files.
123 #define BATTFS_MAX_FILES (1 << (CPU_BITS_PER_CHAR * sizeof(inode_t)))
129 * Sentinel used to keep trace of unset pages in disk->page_array.
131 #define PAGE_UNSET_SENTINEL ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
134 * Type interface for disk init function.
135 * \return true if all is ok, false otherwise.
137 typedef bool (*disk_open_t) (struct BattFsSuper *d);
140 * Type interface for disk page read function.
141 * \a page is the page address, \a addr the address inside the page,
142 * \a size the lenght to be read.
143 * \return the number of bytes read.
145 typedef size_t (*disk_page_read_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t);
148 * Type interface for disk page write function.
149 * \a page is the page address, \a addr the address inside the page,
150 * \a size the lenght to be written.
151 * \return the number of bytes written.
153 typedef size_t (*disk_page_write_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, const void *buf, size_t);
156 * Type interface for disk page erase function.
157 * \a page is the page address.
158 * \return true if all is ok, false otherwise.
160 typedef bool (*disk_page_erase_t) (struct BattFsSuper *d, pgcnt_t page);
163 * Type interface for disk deinit function.
164 * \return true if all is ok, false otherwise.
166 typedef bool (*disk_close_t) (struct BattFsSuper *d);
169 typedef uint32_t disk_size_t; ///< Type for disk sizes.
172 * Context used to describe a disk.
173 * This context structure will be used to access disk.
174 * Must be initialized by hw memory driver.
176 typedef struct BattFsSuper
178 disk_open_t open; ///< Disk init.
179 disk_page_read_t read; ///< Page read.
180 disk_page_write_t write; ///< Page write.
181 disk_page_erase_t erase; ///< Page erase.
182 disk_close_t close; ///< Disk deinit.
184 pgaddr_t page_size; ///< Size of a disk page, in bytes.
185 pgcnt_t page_count; ///< Number of pages on disk.
188 * Page allocation array.
189 * This array must be allocated somewhere and
190 * must have enough space for page_count elements.
191 * Is used by the filesystem to represent
192 * the entire disk in memory.
197 * Lowest free page counter.
198 * This is the counter of the first availble free page.
203 * Highest free page counter.
204 * This value is the next to be used to mark a block as free.
208 disk_size_t disk_size; ///< Size of the disk, in bytes (page_count * page_size).
209 disk_size_t free_bytes; ///< Free space on the disk.
211 List file_opened_list; ///< List used to keep trace of open files.
212 /* TODO add other fields. */
215 typedef uint8_t filemode_t; ///< Type for file open modes.
216 typedef uint32_t file_size_t; ///< Type for file sizes.
219 * Modes for battfs_fileopen.
222 #define BATTFS_CREATE BV(0) ///< Create file if does not exist
223 #define BATTFS_RD BV(1) ///< Open file for reading
224 #define BATTFS_WR BV(2) ///< Open file fir writing
229 * Describe a BattFs file usign a KFile.
231 typedef struct KFileBattFs
233 KFile fd; ///< KFile context
234 Node link; ///< Link for inserting in opened file list
235 inode_t inode; ///< inode of the opened file
236 BattFsSuper *disk; ///< Disk context
237 filemode_t mode; ///< File open mode
238 pgcnt_t *start; ///< Pointer to page_array file start position.
242 * Id for battfs file descriptors.
244 #define KFT_BATTFS MAKE_ID('B', 'T', 'F', 'S')
247 * Macro used to cast a KFile to a KFileBattFs.
248 * Also perform dynamic type check.
250 INLINE KFileBattFs * KFILEBATTFS(KFile *fd)
252 ASSERT(fd->_type == KFT_BATTFS);
253 return (KFileBattFs *)fd;
256 bool battfs_init(struct BattFsSuper *d);
257 bool battfs_close(struct BattFsSuper *disk);
259 bool battfs_fileExists(BattFsSuper *disk, inode_t inode);
260 bool battfs_fileopen(BattFsSuper *disk, KFileBattFs *fd, inode_t inode, filemode_t mode);
262 bool battfs_writeTestBlock(struct BattFsSuper *disk, pgcnt_t page, inode_t inode, seq_t seq, fill_t fill, pgoff_t pgoff, mark_t mark);
264 #endif /* FS_BATTFS_H */