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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 <struct/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 uint8_t inode_t; ///< Type for file inodes
55 typedef uint8_t seq_t; ///< Type for page seq number
56 typedef rotating_t fcs_t; ///< Type for header FCS.
59 * Size required for free block allocation is at least 1 bit more
60 * than page addressing.
62 STATIC_ASSERT(sizeof(seq_t) > sizeof(pgcnt_t));
65 * BattFS page header, used to represent a page
67 * To see how this is stored on disk:
71 typedef struct BattFsPageHeader
73 inode_t inode; ///< File inode (file identifier).
74 fill_t fill; ///< Filled bytes in page.
75 pgoff_t pgoff; ///< Page offset inside file.
76 seq_t seq; ///< Page sequence number.
79 * FCS (Frame Check Sequence) of the page header.
85 * Size of the header once saved on disk.
89 #define BATTFS_HEADER_LEN 10
92 * Half-size of page sequence numer.
94 #define HALF_SEQ (1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t)))
97 * Max sequence number.
99 #define MAX_SEQ ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t) + 1)) - 1)
103 * Maximum page address.
105 #define MAX_PAGE_ADDR ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
108 * Max number of files.
110 #define BATTFS_MAX_FILES (1 << (CPU_BITS_PER_CHAR * sizeof(inode_t)))
116 * Sentinel used to keep trace of unset pages in disk->page_array.
118 #define PAGE_UNSET_SENTINEL ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
120 /** Also used as an error marker sometimes */
121 #define PAGE_ERROR PAGE_UNSET_SENTINEL
124 * Type interface for disk init function.
125 * \return true if all is ok, false otherwise.
127 typedef bool (*disk_open_t) (struct BattFsSuper *d);
130 * Type interface for disk page read function.
131 * \a page is the page address, \a addr the address inside the page,
132 * \a size the lenght to be read.
133 * \return the number of bytes read.
135 typedef size_t (*disk_page_read_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t);
138 * Type interface for disk page write function.
139 * \a page is the page address, \a addr the address inside the page,
140 * \a size the lenght to be written.
141 * \return the number of bytes written.
143 typedef size_t (*disk_page_write_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, const void *buf, size_t);
146 * Type interface for disk page erase function.
147 * \a page is the page address.
148 * \return true if all is ok, false otherwise.
150 typedef bool (*disk_page_erase_t) (struct BattFsSuper *d, pgcnt_t page);
153 * Type interface for disk deinit function.
154 * \return true if all is ok, false otherwise.
156 typedef bool (*disk_close_t) (struct BattFsSuper *d);
159 typedef uint32_t disk_size_t; ///< Type for disk sizes.
162 * Context used to describe a disk.
163 * This context structure will be used to access disk.
164 * Must be initialized by hw memory driver.
166 typedef struct BattFsSuper
168 disk_open_t open; ///< Disk init.
169 disk_page_read_t read; ///< Page read.
170 disk_page_write_t write; ///< Page write.
171 disk_page_erase_t erase; ///< Page erase.
172 disk_close_t close; ///< Disk deinit.
174 pgaddr_t page_size; ///< Size of a disk page, in bytes.
175 pgcnt_t page_count; ///< Number of pages on disk.
178 * Page allocation array.
179 * This array must be allocated somewhere and
180 * must have enough space for page_count elements.
181 * Is used by the filesystem to represent
182 * the entire disk in memory.
187 * Lowest address, in page array, for free pages.
188 * Pages above this element are free for use.
190 pgcnt_t free_page_start;
192 disk_size_t disk_size; ///< Size of the disk, in bytes (page_count * page_size).
193 disk_size_t free_bytes; ///< Free space on the disk.
195 List file_opened_list; ///< List used to keep trace of open files.
196 /* TODO add other fields. */
199 typedef uint8_t filemode_t; ///< Type for file open modes.
200 typedef uint32_t file_size_t; ///< Type for file sizes.
203 * Modes for battfs_fileopen.
206 #define BATTFS_CREATE BV(0) ///< Create file if does not exist
207 #define BATTFS_RD BV(1) ///< Open file for reading
208 #define BATTFS_WR BV(2) ///< Open file fir writing
213 * Describe a BattFs file usign a KFile.
215 typedef struct BattFs
217 KFile fd; ///< KFile context
218 Node link; ///< Link for inserting in opened file list
219 inode_t inode; ///< inode of the opened file
220 BattFsSuper *disk; ///< Disk context
221 filemode_t mode; ///< File open mode
222 pgcnt_t *start; ///< Pointer to page_array file start position.
226 * Id for battfs file descriptors.
228 #define KFT_BATTFS MAKE_ID('B', 'T', 'F', 'S')
231 * Macro used to cast a KFile to a BattFS.
232 * Also perform dynamic type check.
234 INLINE BattFs * BATTFS_CAST(KFile *fd)
236 ASSERT(fd->_type == KFT_BATTFS);
240 bool battfs_init(struct BattFsSuper *d);
241 bool battfs_close(struct BattFsSuper *disk);
243 bool battfs_fileExists(BattFsSuper *disk, inode_t inode);
244 bool battfs_fileopen(BattFsSuper *disk, BattFs *fd, inode_t inode, filemode_t mode);
246 bool battfs_writeTestBlock(struct BattFsSuper *disk, pgcnt_t page, inode_t inode, seq_t seq, fill_t fill, pgoff_t pgoff, seq_t seq);
247 #endif /* FS_BATTFS_H */