fat16int.h

包装了一个开源的FAT16文件系统

#ifndef __FAT16INT_H__
#define __FAT16INT_H__
#define FAT16_CLUSTER_FREE 0x0000
#define FAT16_CLUSTER_RESERVED_MIN 0xfff0
#define FAT16_CLUSTER_RESERVED_MAX 0xfff6
#define FAT16_CLUSTER_BAD 0xfff7
#define FAT16_CLUSTER_LAST_MIN 0xfff8
#define FAT16_CLUSTER_LAST_MAX 0xffff

#define FAT16_DIRENTRY_DELETED 0xe5
#define FAT16_DIRENTRY_LFNLAST (1 << 6)
#define FAT16_DIRENTRY_LFNSEQMASK ((1 << 6) - 1)

/* Each entry within the directory table has a size of 32 bytes
* and either contains a 8.3 DOS-style file name or a part of a
* long file name, which may consist of several directory table
* entries at once.
*
* multi-byte integer values are stored little-endian!
*
* 8.3 file name entry:
* ====================
* offset  length  description
*      0       8  name (space padded)
*      8       3  extension (space padded)
*     11       1  attributes (FAT16_ATTRIB_*)
*
* long file name (lfn) entry ordering for a single file name:
* ===========================================================
* LFN entry n
*     ...
* LFN entry 2
* LFN entry 1
* 8.3 entry (see above)
* 
* lfn entry:
* ==========
* offset  length  description
*      0       1  ordinal field
*      1       2  unicode character 1
*      3       3  unicode character 2
*      5       3  unicode character 3
*      7       3  unicode character 4
*      9       3  unicode character 5
*     11       1  attribute (always 0x0f)
*     12       1  type (reserved, always 0)
*     13       1  checksum
*     14       2  unicode character 6
*     16       2  unicode character 7
*     18       2  unicode character 8
*     20       2  unicode character 9
*     22       2  unicode character 10
*     24       2  unicode character 11
*     26       2  cluster (unused, always 0)
*     28       2  unicode character 12
*     30       2  unicode character 13
* 
* The ordinal field contains a descending number, from n to 1.
* For the n'th lfn entry the ordinal field is or'ed with 0x40.
* For deleted lfn entries, the ordinal field is set to 0xe5.
*/

struct fat16_header_struct
{
	uint32_t size;

	uint32_t fat_offset;
	uint32_t fat_size;

	uint16_t sector_size;
	uint16_t cluster_size;

	uint32_t root_dir_offset;

	uint32_t cluster_zero_offset;
};

struct fat16_fs_struct
{
	struct partition_struct* partition;
	struct fat16_header_struct header;
};

struct fat16_file_struct
{
	struct fat16_fs_struct* fs;
	struct fat16_dir_entry_struct dir_entry;
	uint32_t pos;
	uint16_t pos_cluster;
};

struct fat16_dir_struct
{
	struct fat16_fs_struct* fs;
	struct fat16_dir_entry_struct dir_entry;
	uint16_t entry_next;
};

struct fat16_read_callback_arg
{
	uint16_t entry_cur;
	uint16_t entry_num;
	uint32_t entry_offset;
	uint8_t byte_count;
};

struct fat16_usage_count_callback_arg
{
	uint16_t cluster_count;
	uint8_t buffer_size;
};

#if !USE_DYNAMIC_MEMORY
static struct fat16_fs_struct fat16_fs_handlers[FAT16_FS_COUNT];
static struct fat16_file_struct fat16_file_handlers[FAT16_FILE_COUNT];
static struct fat16_dir_struct fat16_dir_handlers[FAT16_DIR_COUNT];
#endif

static uint8_t fat16_read_header(struct fat16_fs_struct* fs);
static uint8_t fat16_read_root_dir_entry(const struct fat16_fs_struct* fs, uint16_t entry_num, struct fat16_dir_entry_struct* dir_entry);
static uint8_t fat16_read_sub_dir_entry(const struct fat16_fs_struct* fs, uint16_t entry_num, const struct fat16_dir_entry_struct* parent, struct fat16_dir_entry_struct* dir_entry);
static uint8_t fat16_dir_entry_seek_callback(uint8_t* buffer, uint32_t offset, void* p);
static uint8_t fat16_dir_entry_read_callback(uint8_t* buffer, uint32_t offset, void* p);
static uint8_t fat16_interpret_dir_entry(struct fat16_dir_entry_struct* dir_entry, const uint8_t* raw_entry);
static uint16_t fat16_get_next_cluster(const struct fat16_fs_struct* fs, uint16_t cluster_num);
static uint16_t fat16_append_clusters(const struct fat16_fs_struct* fs, uint16_t cluster_num, uint16_t count);
static uint8_t fat16_free_clusters(const struct fat16_fs_struct* fs, uint16_t cluster_num);
static uint8_t fat16_terminate_clusters(const struct fat16_fs_struct* fs, uint16_t cluster_num);
static uint8_t fat16_clear_cluster(const struct fat16_fs_struct* fs, uint16_t cluster_num);
static uint16_t fat16_clear_cluster_callback(uint8_t* buffer, uint32_t offset, void* p);
static uint32_t fat16_find_offset_for_dir_entry(const struct fat16_fs_struct* fs, const struct fat16_dir_struct* parent, const struct fat16_dir_entry_struct* dir_entry);
static uint8_t fat16_write_dir_entry(const struct fat16_fs_struct* fs, struct fat16_dir_entry_struct* dir_entry);

static uint8_t fat16_get_fs_free_callback(uint8_t* buffer, uint32_t offset, void* p);

static void fat16_set_file_modification_date(struct fat16_dir_entry_struct* dir_entry, uint16_t year, uint8_t month, uint8_t day);
static void fat16_set_file_modification_time(struct fat16_dir_entry_struct* dir_entry, uint8_t hour, uint8_t min, uint8_t sec);
#endif