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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 uint64_t seq_t; ///< Type for page seq number, at least 40bits wide.
56 typedef rotating_t fcs_t; ///< Type for header FCS.
60 * BattFS page header, used to represent a page
62 * To see how this is stored on disk:
66 typedef struct BattFsPageHeader
68 inode_t inode; ///< File inode (file identifier).
69 fill_t fill; ///< Filled bytes in page.
70 pgoff_t pgoff; ///< Page offset inside file.
73 * Page sequence number.
74 * Every time a page is rewritten the seq number is
75 * increased by 1. seq_t is wide enough to not to perform
76 * a wrap around before the memory death.
77 * So it can be kept as it would be
78 * monotonically increasing for our needs.
83 * FCS (Frame Check Sequence) of the page header.
89 * Size of the header once saved on disk.
93 #define BATTFS_HEADER_LEN 12
96 * Maximum page address.
98 #define MAX_PAGE_ADDR ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
101 * Max number of files.
103 #define BATTFS_MAX_FILES (1 << (CPU_BITS_PER_CHAR * sizeof(inode_t)))
109 * Sentinel used to keep trace of unset pages in disk->page_array.
111 #define PAGE_UNSET_SENTINEL ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
114 * Type interface for disk init function.
115 * \return true if all is ok, false otherwise.
117 typedef bool (*disk_open_t) (struct BattFsSuper *d);
120 * Type interface for disk page read function.
121 * \a page is the page address, \a addr the address inside the page,
122 * \a size the lenght to be read.
123 * \return the number of bytes read.
125 typedef size_t (*disk_page_read_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t);
128 * Type interface for disk page write function.
129 * \a page is the page address, \a addr the address inside the page,
130 * \a size the lenght to be written.
131 * \return the number of bytes written.
133 typedef size_t (*disk_page_write_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, const void *buf, size_t);
136 * Type interface for disk page erase function.
137 * \a page is the page address.
138 * \return true if all is ok, false otherwise.
140 typedef bool (*disk_page_erase_t) (struct BattFsSuper *d, pgcnt_t page);
143 * Type interface for disk deinit function.
144 * \return true if all is ok, false otherwise.
146 typedef bool (*disk_close_t) (struct BattFsSuper *d);
149 typedef uint32_t disk_size_t; ///< Type for disk sizes.
152 * Context used to describe a disk.
153 * This context structure will be used to access disk.
154 * Must be initialized by hw memory driver.
156 typedef struct BattFsSuper
158 disk_open_t open; ///< Disk init.
159 disk_page_read_t read; ///< Page read.
160 disk_page_write_t write; ///< Page write.
161 disk_page_erase_t erase; ///< Page erase.
162 disk_close_t close; ///< Disk deinit.
164 pgaddr_t page_size; ///< Size of a disk page, in bytes.
165 pgcnt_t page_count; ///< Number of pages on disk.
168 * Page allocation array.
169 * This array must be allocated somewhere and
170 * must have enough space for page_count elements.
171 * Is used by the filesystem to represent
172 * the entire disk in memory.
177 * Lowest address, in page array, for free pages.
178 * Pages above this element are free for use.
180 pgcnt_t free_page_start;
182 disk_size_t disk_size; ///< Size of the disk, in bytes (page_count * page_size).
183 disk_size_t free_bytes; ///< Free space on the disk.
185 List file_opened_list; ///< List used to keep trace of open files.
186 /* TODO add other fields. */
189 typedef uint8_t filemode_t; ///< Type for file open modes.
190 typedef int32_t file_size_t; ///< Type for file sizes.
193 * Modes for battfs_fileopen.
196 #define BATTFS_CREATE BV(0) ///< Create file if does not exist
197 #define BATTFS_RD BV(1) ///< Open file for reading
198 #define BATTFS_WR BV(2) ///< Open file fir writing
203 * Describe a BattFs file usign a KFile.
205 typedef struct BattFs
207 KFile fd; ///< KFile context
208 Node link; ///< Link for inserting in opened file list
209 inode_t inode; ///< inode of the opened file
210 BattFsSuper *disk; ///< Disk context
211 filemode_t mode; ///< File open mode
212 pgcnt_t *start; ///< Pointer to page_array file start position.
216 * Id for battfs file descriptors.
218 #define KFT_BATTFS MAKE_ID('B', 'T', 'F', 'S')
221 * Macro used to cast a KFile to a BattFS.
222 * Also perform dynamic type check.
224 INLINE BattFs * BATTFS_CAST(KFile *fd)
226 ASSERT(fd->_type == KFT_BATTFS);
230 bool battfs_init(struct BattFsSuper *d);
231 bool battfs_close(struct BattFsSuper *disk);
233 bool battfs_fileExists(BattFsSuper *disk, inode_t inode);
234 bool battfs_fileopen(BattFsSuper *disk, BattFs *fd, inode_t inode, filemode_t mode);
235 bool battfs_writeTestBlock(struct BattFsSuper *disk, pgcnt_t page, inode_t inode, seq_t seq, fill_t fill, pgoff_t pgoff);
236 #endif /* FS_BATTFS_H */