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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>
48 typedef uint16_t fill_t;
49 typedef fill_t pgaddr_t;
50 typedef uint16_t pgoff_t;
51 typedef uint32_t mark_t;
52 typedef uint8_t mark_roll_t;
53 typedef uint8_t inode_t;
54 typedef uint8_t seq_t;
55 typedef rotating_t fcs_t;
58 * Size required for free block allocation is at least 1 bit more
59 * than page addressing.
61 STATIC_ASSERT(sizeof(mark_t) > sizeof(pgaddr_t));
64 * BattFS page header, used to represent a page
66 * To see how this is stored on disk:
70 typedef struct BattFsPageHeader
72 inode_t inode; ///< File inode (file identifier).
73 seq_t seq; ///< Page sequence number.
74 fill_t fill; ///< Filled bytes in page.
75 pgoff_t pgoff; ///< Page offset inside file.
76 mark_t mark; ///< Marker used to keep trace of free/used pages.
79 * FCS (Frame Check Sequence) of the page header once the page
80 * as been marked as free.
85 * FCS (Frame Check Sequence) of the page header.
91 * Size of the header once saved on disk.
95 #define BATTFS_HEADER_LEN 12
98 * Marks for valid pages.
99 * Simply set to 1 all field bits.
102 #define MARK_PAGE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(pgaddr_t) + 1)) - 1)
103 #define FCS_FREE_VALID ((1 << (CPU_BITS_PER_CHAR * sizeof(fcs_t))) - 1)
108 * Half-size of free page marker.
109 * Used to keep trace of free marker wrap-arounds.
111 #define MARK_HALF_SIZE (1 << (CPU_BITS_PER_CHAR * sizeof(pgaddr_t) + 1))
114 * Maximum page address.
116 #define MAX_PAGE_ADDR ((1 << (CPU_BITS_PER_CHAR * sizeof(pgaddr_t))) - 1)
119 * Max number of files.
121 #define BATTFS_MAX_FILES (1 << (CPU_BITS_PER_CHAR * sizeof(inode_t)))
127 * Type for disk page addressing.
129 typedef uint16_t pgcnt_t;
132 * Sentinel used to keep trace of unset pages in disk->page_array.
134 #define PAGE_UNSET_SENTINEL ((1 << (CPU_BITS_PER_CHAR * sizeof(pgcnt_t))) - 1)
137 * Type interface for disk init function.
138 * \return true if all is ok, false otherwise.
140 typedef bool (*disk_open_t) (struct BattFsSuper *d);
143 * Type interface for disk page read function.
144 * \a page is the page address, \a addr the address inside the page,
145 * \a size the lenght to be read.
146 * \return the number of bytes read.
148 typedef size_t (*disk_page_read_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, void *buf, size_t);
151 * Type interface for disk page write function.
152 * \a page is the page address, \a addr the address inside the page,
153 * \a size the lenght to be written.
154 * \return the number of bytes written.
156 typedef size_t (*disk_page_write_t) (struct BattFsSuper *d, pgcnt_t page, pgaddr_t addr, const void *buf, size_t);
159 * Type interface for disk page erase function.
160 * \a page is the page address.
161 * \return true if all is ok, false otherwise.
163 typedef bool (*disk_page_erase_t) (struct BattFsSuper *d, pgcnt_t page);
166 * Type interface for disk deinit function.
167 * \return true if all is ok, false otherwise.
169 typedef bool (*disk_close_t) (struct BattFsSuper *d);
172 typedef uint32_t disk_size_t; ///< Type for disk sizes.
175 * Context used to describe a disk.
176 * This context structure will be used to access disk.
177 * Must be initialized by hw memory driver.
179 typedef struct BattFsSuper
181 disk_open_t open; ///< Disk init.
182 disk_page_read_t read; ///< Page read.
183 disk_page_write_t write; ///< Page write.
184 disk_page_erase_t erase; ///< Page erase.
185 disk_close_t close; ///< Disk deinit.
187 pgaddr_t page_size; ///< Size of a disk page, in bytes.
188 pgcnt_t page_count; ///< Number of pages on disk.
191 * Page allocation array.
192 * This array must be allocated somewhere and
193 * must have enough space for page_count elements.
194 * Is used by the filesystem to represent
195 * the entire disk in memory.
200 * Lowest free page counter.
201 * This is the counter of the first availble free page.
206 * Highest free page counter.
207 * This value is the next to be used to mark a block as free.
211 disk_size_t disk_size; ///< Size of the disk, in bytes (page_count * page_size).
212 disk_size_t free_bytes; ///< Free space on the disk.
214 /* TODO add other fields. */
217 bool battfs_init(struct BattFsSuper *d);
218 bool battfs_close(struct BattFsSuper *disk);
220 bool battfs_writeTestBlock(struct BattFsSuper *disk, pgcnt_t page, inode_t inode, seq_t seq, fill_t fill, pgoff_t pgoff, mark_t mark);
222 #endif /* FS_BATTFS_H */