MMC/SD memory card interface

Detailed Description

This module implements read and write support for MMC and SD cards.

It includes

low-level MMC read/write routines
partition table support
a simple FAT16 read/write implementation

Files

file sd.c

MMC/SD handling (license: GPLv2).

file sd.h

MMC/SD handling header (license: GPLv2).

Modules

FAT16 support

This module implements FAT16 read and write access.

Partition table support

Support for reading partition tables and access to partitions.

MMC/SD configuration

Compile time configuration common to all MMC/SD modules.

MMC/SD card raw access

This module implements read and write access to MMC and SD cards.

Data Structures

struct fat16_dir_entry_struct

Describes a directory entry. More...

Functions

struct fat16_fs_struct * fat16_open (struct partition_struct *partition)

Opens a FAT16 filesystem.

void fat16_close (struct fat16_fs_struct *fs)

Closes a FAT16 filesystem.

struct fat16_file_struct * fat16_open_file (struct fat16_fs_struct *fs, const struct fat16_dir_entry_struct *dir_entry)

Opens a file on a FAT16 filesystem.

void fat16_close_file (struct fat16_file_struct *fd)

Closes a file.

int16_t fat16_read_file (struct fat16_file_struct *fd, uint8_t *buffer, uint16_t buffer_len)

Reads data from a file.

int16_t fat16_write_file (struct fat16_file_struct *fd, const uint8_t *buffer, uint16_t buffer_len)

Writes data to a file.

uint8_t fat16_seek_file (struct fat16_file_struct *fd, int32_t *offset, uint8_t whence)

Repositions the read/write file offset.

uint8_t fat16_resize_file (struct fat16_file_struct *fd, uint32_t size)

Resizes a file to have a specific size.

struct fat16_dir_struct * fat16_open_dir (struct fat16_fs_struct *fs, const struct fat16_dir_entry_struct *dir_entry)

Opens a directory.

void fat16_close_dir (struct fat16_dir_struct *dd)

Closes a directory descriptor.

uint8_t fat16_read_dir (struct fat16_dir_struct *dd, struct fat16_dir_entry_struct *dir_entry)

Reads the next directory entry contained within a parent directory.

uint8_t fat16_reset_dir (struct fat16_dir_struct *dd)

Resets a directory handle.

uint8_t fat16_create_file (struct fat16_dir_struct *parent, const char *file, struct fat16_dir_entry_struct *dir_entry)

Creates a file.

uint8_t fat16_delete_file (struct fat16_fs_struct *fs, struct fat16_dir_entry_struct *dir_entry)

Deletes a file or directory.

uint8_t fat16_create_dir (struct fat16_dir_struct *parent, const char *dir, struct fat16_dir_entry_struct *dir_entry)

Creates a directory.

void fat16_get_file_modification_date (const struct fat16_dir_entry_struct *dir_entry, uint16_t *year, uint8_t *month, uint8_t *day)

Returns the modification date of a file.

void fat16_get_file_modification_time (const struct fat16_dir_entry_struct *dir_entry, uint8_t *hour, uint8_t *min, uint8_t *sec)

Returns the modification time of a file.

uint8_t fat16_get_dir_entry_of_path (struct fat16_fs_struct *fs, const char *path, struct fat16_dir_entry_struct *dir_entry)

Retrieves the directory entry of a path.

uint32_t fat16_get_fs_size (const struct fat16_fs_struct *fs)

Returns the amount of total storage capacity of the filesystem in bytes.

uint32_t fat16_get_fs_free (const struct fat16_fs_struct *fs)

Returns the amount of free storage capacity on the filesystem in bytes.

Function Documentation

struct fat16_fs_struct* fat16_open ( struct partition_struct * partition ) [read]

Opens a FAT16 filesystem.

Parameters:

[in] partition Discriptor of partition on which the filesystem resides.

Returns:: 0 on error, a FAT16 filesystem descriptor on success.

See also:: fat16_open

void fat16_close ( struct fat16_fs_struct * fs )

Closes a FAT16 filesystem.

When this function returns, the given filesystem descriptor will be invalid.

Parameters:

[in] fs The filesystem to close.

See also:: fat16_open

struct fat16_file_struct* fat16_open_file	(	struct fat16_fs_struct *	fs,
		const struct fat16_dir_entry_struct *	dir_entry
	)			`[read]`

Opens a file on a FAT16 filesystem.

Parameters:

`[in]`	fs	The filesystem on which the file to open lies.
`[in]`	dir_entry	The directory entry of the file to open.

Returns:: The file handle, or 0 on failure.

See also:: fat16_close_file

void fat16_close_file ( struct fat16_file_struct * fd )

Closes a file.

Parameters:

[in] fd The file handle of the file to close.

See also:: fat16_open_file

int16_t fat16_read_file	(	struct fat16_file_struct *	fd,
		uint8_t *	buffer,
		uint16_t	buffer_len
	)

Reads data from a file.

The data requested is read from the current file location.

Parameters:

`[in]`	fd	The file handle of the file from which to read.
`[out]`	buffer	The buffer into which to write.
`[in]`	buffer_len	The amount of data to read.

Returns:: The number of bytes read, 0 on end of file, or -1 on failure.

See also:: fat16_write_file

int16_t fat16_write_file	(	struct fat16_file_struct *	fd,
		const uint8_t *	buffer,
		uint16_t	buffer_len
	)

Writes data to a file.

The data is written to the current file location.

Parameters:

`[in]`	fd	The file handle of the file to which to write.
`[in]`	buffer	The buffer from which to read the data to be written.
`[in]`	buffer_len	The amount of data to write.

Returns:: The number of bytes written, 0 on disk full, or -1 on failure.

See also:: fat16_read_file

uint8_t fat16_seek_file	(	struct fat16_file_struct *	fd,
		int32_t *	offset,
		uint8_t	whence
	)

Repositions the read/write file offset.

Changes the file offset where the next call to fat16_read_file() or fat16_write_file() starts reading/writing.

If the new offset is beyond the end of the file, fat16_resize_file() is implicitly called, i.e. the file is expanded.

The new offset can be given in different ways determined by the whence parameter:

FAT16_SEEK_SET: *offset is relative to the beginning of the file.
FAT16_SEEK_CUR: *offset is relative to the current file position.
FAT16_SEEK_END: *offset is relative to the end of the file.

The resulting absolute offset is written to the location the offset parameter points to.

Parameters:

`[in]`	fd	The file decriptor of the file on which to seek.
`[in,out]`	offset	A pointer to the new offset, as affected by the `whence` parameter. The function writes the new absolute offset to this location before it returns.
`[in]`	whence	Affects the way `offset` is interpreted, see above.

Returns:: 0 on failure, 1 on success.

uint8_t fat16_resize_file	(	struct fat16_file_struct *	fd,
		uint32_t	size
	)

Resizes a file to have a specific size.

Enlarges or shrinks the file pointed to by the file descriptor to have exactly the specified size.

If the file is truncated, all bytes having an equal or larger offset than the given size are lost. If the file is expanded, the additional bytes are allocated.

Note:: Please be aware that this function just allocates or deallocates disk space, it does not explicitely clear it. To avoid data leakage, this must be done manually.

Parameters:

`[in]`	fd	The file decriptor of the file which to resize.
`[in]`	size	The new size of the file.

Returns:: 0 on failure, 1 on success.

struct fat16_dir_struct* fat16_open_dir	(	struct fat16_fs_struct *	fs,
		const struct fat16_dir_entry_struct *	dir_entry
	)			`[read]`

Opens a directory.

Parameters:

`[in]`	fs	The filesystem on which the directory to open resides.
`[in]`	dir_entry	The directory entry which stands for the directory to open.

Returns:: An opaque directory descriptor on success, 0 on failure.

See also:: fat16_close_dir

void fat16_close_dir ( struct fat16_dir_struct * dd )

Closes a directory descriptor.

This function destroys a directory descriptor which was previously obtained by calling fat16_open_dir(). When this function returns, the given descriptor will be invalid.

Parameters:

[in] dd The directory descriptor to close.

See also:: fat16_open_dir

uint8_t fat16_read_dir	(	struct fat16_dir_struct *	dd,
		struct fat16_dir_entry_struct *	dir_entry
	)

Reads the next directory entry contained within a parent directory.

Parameters:

`[in]`	dd	The descriptor of the parent directory from which to read the entry.
`[out]`	dir_entry	Pointer to a buffer into which to write the directory entry information.

Returns:: 0 on failure, 1 on success.

See also:: fat16_reset_dir

uint8_t fat16_reset_dir ( struct fat16_dir_struct * dd )

Resets a directory handle.

Resets the directory handle such that reading restarts with the first directory entry.

Parameters:

[in] dd The directory handle to reset.

Returns:: 0 on failure, 1 on success.

See also:: fat16_read_dir

uint8_t fat16_create_file	(	struct fat16_dir_struct *	parent,
		const char *	file,
		struct fat16_dir_entry_struct *	dir_entry
	)

Creates a file.

Creates a file and obtains the directory entry of the new file. If the file to create already exists, the directory entry of the existing file will be returned within the dir_entry parameter.

Note:: The file name is not checked for invalid characters.
The generation of the short 8.3 file name is quite simple. The first eight characters are used for the filename. The extension, if any, is made up of the first three characters following the last dot within the long filename. If the filename (without the extension) is longer than eight characters, the lower byte of the cluster number replaces the last two characters to avoid name clashes. In any other case, it is your responsibility to avoid name clashes.

Parameters:

`[in]`	parent	The handle of the directory in which to create the file.
`[in]`	file	The name of the file to create.
`[out]`	dir_entry	The directory entry to fill for the new file.

Returns:: 0 on failure, 1 on success.

See also:: fat16_delete_file

uint8_t fat16_delete_file	(	struct fat16_fs_struct *	fs,
		struct fat16_dir_entry_struct *	dir_entry
	)

Deletes a file or directory.

If a directory is deleted without first deleting its subdirectories and files, disk space occupied by these files will get wasted as there is no chance to release it and mark it as free.

Parameters:

`[in]`	fs	The filesystem on which to operate.
`[in]`	dir_entry	The directory entry of the file to delete.

Returns:: 0 on failure, 1 on success.

See also:: fat16_create_file

uint8_t fat16_create_dir	(	struct fat16_dir_struct *	parent,
		const char *	dir,
		struct fat16_dir_entry_struct *	dir_entry
	)

Creates a directory.

Creates a directory and obtains its directory entry. If the directory to create already exists, its directory entry will be returned within the dir_entry parameter.

Note:: The notes which apply to fat16_create_file also apply to this function.

Parameters:

`[in]`	parent	The handle of the parent directory of the new directory.
`[in]`	dir	The name of the directory to create.
`[out]`	dir_entry	The directory entry to fill for the new directory.

Returns:: 0 on failure, 1 on success.

See also:: fat16_delete_dir

void fat16_get_file_modification_date	(	const struct fat16_dir_entry_struct *	dir_entry,
		uint16_t *	year,
		uint8_t *	month,
		uint8_t *	day
	)

Returns the modification date of a file.

Parameters:

`[in]`	dir_entry	The directory entry of which to return the modification date.
`[out]`	year	The year the file was last modified.
`[out]`	month	The month the file was last modified.
`[out]`	day	The day the file was last modified.

void fat16_get_file_modification_time	(	const struct fat16_dir_entry_struct *	dir_entry,
		uint8_t *	hour,
		uint8_t *	min,
		uint8_t *	sec
	)

Returns the modification time of a file.

Parameters:

`[in]`	dir_entry	The directory entry of which to return the modification time.
`[out]`	hour	The hour the file was last modified.
`[out]`	min	The min the file was last modified.
`[out]`	sec	The sec the file was last modified.

uint8_t fat16_get_dir_entry_of_path	(	struct fat16_fs_struct *	fs,
		const char *	path,
		struct fat16_dir_entry_struct *	dir_entry
	)

Retrieves the directory entry of a path.

The given path may both describe a file or a directory.

Parameters:

`[in]`	fs	The FAT16 filesystem on which to search.
`[in]`	path	The path of which to read the directory entry.
`[out]`	dir_entry	The directory entry to fill.

Returns:: 0 on failure, 1 on success.

See also:: fat16_read_dir

uint32_t fat16_get_fs_size ( const struct fat16_fs_struct * fs )

Returns the amount of total storage capacity of the filesystem in bytes.

Parameters:

[in] fs The filesystem on which to operate.

Returns:: 0 on failure, the filesystem size in bytes otherwise.

uint32_t fat16_get_fs_free ( const struct fat16_fs_struct * fs )

Returns the amount of free storage capacity on the filesystem in bytes.

Note:: As the FAT16 filesystem is cluster based, this function does not return continuous values but multiples of the cluster size.

Parameters:

[in] fs The filesystem on which to operate.

Returns:: 0 on failure, the free filesystem space in bytes otherwise.


Files
file	sd.c
	MMC/SD handling (license: GPLv2).
file	sd.h
	MMC/SD handling header (license: GPLv2).
Modules
	FAT16 support
	This module implements FAT16 read and write access.
	Partition table support
	Support for reading partition tables and access to partitions.
	MMC/SD configuration
	Compile time configuration common to all MMC/SD modules.
	MMC/SD card raw access
	This module implements read and write access to MMC and SD cards.
Data Structures
struct	fat16_dir_entry_struct
	Describes a directory entry. More...
Functions
struct fat16_fs_struct *	fat16_open (struct partition_struct *partition)
	Opens a FAT16 filesystem.
void	fat16_close (struct fat16_fs_struct *fs)
	Closes a FAT16 filesystem.
struct fat16_file_struct *	fat16_open_file (struct fat16_fs_struct fs, const struct fat16_dir_entry_struct dir_entry)
	Opens a file on a FAT16 filesystem.
void	fat16_close_file (struct fat16_file_struct *fd)
	Closes a file.
int16_t	fat16_read_file (struct fat16_file_struct fd, uint8_t buffer, uint16_t buffer_len)
	Reads data from a file.
int16_t	fat16_write_file (struct fat16_file_struct fd, const uint8_t buffer, uint16_t buffer_len)
	Writes data to a file.
uint8_t	fat16_seek_file (struct fat16_file_struct fd, int32_t offset, uint8_t whence)
	Repositions the read/write file offset.
uint8_t	fat16_resize_file (struct fat16_file_struct *fd, uint32_t size)
	Resizes a file to have a specific size.
struct fat16_dir_struct *	fat16_open_dir (struct fat16_fs_struct fs, const struct fat16_dir_entry_struct dir_entry)
	Opens a directory.
void	fat16_close_dir (struct fat16_dir_struct *dd)
	Closes a directory descriptor.
uint8_t	fat16_read_dir (struct fat16_dir_struct dd, struct fat16_dir_entry_struct dir_entry)
	Reads the next directory entry contained within a parent directory.
uint8_t	fat16_reset_dir (struct fat16_dir_struct *dd)
	Resets a directory handle.
uint8_t	fat16_create_file (struct fat16_dir_struct parent, const char file, struct fat16_dir_entry_struct *dir_entry)
	Creates a file.
uint8_t	fat16_delete_file (struct fat16_fs_struct fs, struct fat16_dir_entry_struct dir_entry)
	Deletes a file or directory.
uint8_t	fat16_create_dir (struct fat16_dir_struct parent, const char dir, struct fat16_dir_entry_struct *dir_entry)
	Creates a directory.
void	fat16_get_file_modification_date (const struct fat16_dir_entry_struct dir_entry, uint16_t year, uint8_t month, uint8_t day)
	Returns the modification date of a file.
void	fat16_get_file_modification_time (const struct fat16_dir_entry_struct dir_entry, uint8_t hour, uint8_t min, uint8_t sec)
	Returns the modification time of a file.
uint8_t	fat16_get_dir_entry_of_path (struct fat16_fs_struct fs, const char path, struct fat16_dir_entry_struct *dir_entry)
	Retrieves the directory entry of a path.
uint32_t	fat16_get_fs_size (const struct fat16_fs_struct *fs)
	Returns the amount of total storage capacity of the filesystem in bytes.
uint32_t	fat16_get_fs_free (const struct fat16_fs_struct *fs)
	Returns the amount of free storage capacity on the filesystem in bytes.