DragonFS filesystem implementation and newlib hooks. More...

Files
file	dragonfs.c
	DragonFS.

file	dfsinternal.h
	Internal DFS Definitions.

file	dragonfs.h
	DragonFS.

Data Structures
struct	directory_entry_t
	Representation of a directory entry. More...

struct	open_file_t
	Open file handle structure. More...

Macros
#define	ROOT_FLAGS 0xFFFFFFFF
	The special ID value in directory_entry::flags defining the root sector.

#define	ROOT_NEXT_ENTRY 0xDEADBEEF
	The special ID value in directory_entry::next_entry defining the root sector.

#define	ROOT_PATH "DragonFS 2.0"
	Special path value in directory_entry::path defining the root sector.

#define	SECTOR_SIZE 256
	The size of a sector.

#define	SECTOR_PAYLOAD 252
	The size of a sector payload.

#define	DFS_DEFAULT_LOCATION 0
	Default filesystem location. More...

#define	MAX_OPEN_FILES 4
	Maximum open files in DragonFS.

#define	MAX_FILENAME_LEN 243
	Maximum filename length. More...

#define	MAX_DIRECTORY_DEPTH 100
	Maximum depth of directories supported.

#define	FILETYPE(x) ((x) & 3)
	Macro to extract the file type from a DragonFS file flag. More...

Enumerations
enum	{ WALK_CHDIR , WALK_OPEN }
	Directory walking flags. More...

enum	{ TYPE_ANY , TYPE_FILE , TYPE_DIR }
	Directory walking return flags. More...

Functions
int	dfs_chdir (const char *const path)
	Change directories to the specified path. More...

int	dfs_dir_findfirst (const char const path, char buf)
	Find the first file or directory in a directory listing. More...

int	dfs_dir_findnext (char *buf)
	Find the next file or directory in a directory listing. More...

int	dfs_open (const char *const path)
	Open a file given a path. More...

int	dfs_close (uint32_t handle)
	Close an already open file handle. More...

int	dfs_seek (uint32_t handle, int offset, int origin)
	Seek to an offset in the file. More...

int	dfs_tell (uint32_t handle)
	Return the current offset into a file. More...

int	dfs_read (void *const buf, int size, int count, uint32_t handle)
	Read data from a file. More...

int	dfs_size (uint32_t handle)
	Return the file size of an open file. More...

uint32_t	dfs_rom_addr (const char *path)
	Return the physical address of a file (in ROM space) More...

int	dfs_eof (uint32_t handle)
	Return whether the end of file has been reached. More...

int	dfs_init (uint32_t base_fs_loc)
	Initialize the filesystem. More...

const char *	dfs_strerror (int error)
	Convert DFS error code into an error string.

DragonFS Return values
#define	DFS_ESUCCESS 0
	Success.

#define	DFS_EBADINPUT -1
	Input parameters invalid.

#define	DFS_ENOFILE -2
	File does not exist.

#define	DFS_EBADFS -3
	Bad filesystem.

#define	DFS_ENFILE -4
	Too many open files.

#define	DFS_EBADHANDLE -5
	Invalid file handle.

DragonFS file type flags
#define	FLAGS_FILE 0x0
	This is a file entry.

#define	FLAGS_DIR 0x1
	This is a directory entry.

#define	FLAGS_EOF 0x2
	This is the end of a directory list.

Detailed Description

DragonFS filesystem implementation and newlib hooks.

DragonFS is a read only ROM filesystem for the N64. It provides an interface that homebrew developers can use to load resources from cartridge space that were not available at compile time. This can mean sprites or other game assets, or the filesystem can be appended at a later time if the homebrew developer wishes end users to be able to insert custom levels, music or other assets. It is loosely based off of FAT with consideration into application and limitations of the N64.

The filesystem can be generated using 'mkdfs' which is included in the 'tools' directory of libdragon. Due to the read-only nature, DFS does not support empty files or empty directories. Attempting to create a filesystem with either of these using 'mkdfs' will result in an error. If a filesystem contains either empty files or empty directories, the result of manipulating the filesystem is undefined.

DragonFS does not support writing, renaming or symlinking of files. It supports only file and directory types.

DFS files have a maximum size of 256 MiB. Directories can have an unlimited number of files in them. Each token (separated by a / in the path) can be 243 characters maximum. Directories can be 100 levels deep at maximum. There can be 4 files open simultaneously.

When DFS is initialized, it will register itself with newlib using 'rom:/' as a prefix. Files can be accessed either with standard POSIX functions (open, fopen) using the 'rom:/' prefix or the lower-level DFS API calls without prefix. In most cases, it is not necessary to use the DFS API directly, given that the standard C functions are more comprehensive. Files can be opened using both sets of API calls simultaneously as long as no more than four files are open at any one time.

DragonFS does not support file compression; if you want to compress your assets, use the asset API (asset_load / asset_fopen).

Data Structure Documentation

◆ directory_entry

struct directory_entry

Representation of a directory entry.

Type definition.

Data Fields
uint32_t	next_entry	Offset to next directory entry.
uint32_t	flags	File size and flags. See FLAGS_FILE, FLAGS_DIR and FLAGS_EOF.
char	path[MAX_FILENAME_LEN+1]	The file or directory name.
uint32_t	file_pointer	Offset to start sector of the file.

◆ open_file_t

struct open_file_t

Open file handle structure.

Data Fields
uint8_t	cached_data[512]	Cached data to speed up small reads. We want this buffer to be 8-byte aligned for DMA, but also 16-byte aligned so that it doesn't share cachelines with other members of the structure, so it's easier to handle coherency.
uint32_t	cached_loc	location of the cached data
uint32_t	handle	The unique file handle to refer to this file by.
uint32_t	size	The size in bytes of this file.
uint32_t	loc	The offset of the current location in the file.
uint32_t	cart_start_loc	The offset within the filesystem where the file is stored.

Macro Definition Documentation

◆ DFS_DEFAULT_LOCATION

#define DFS_DEFAULT_LOCATION 0

Default filesystem location.

The default value 0 instruct dfs_init to search for the DFS image within the rompak.

◆ MAX_FILENAME_LEN

#define MAX_FILENAME_LEN 243

Maximum filename length.

This value is due to the direcory structure

◆ FILETYPE

#define FILETYPE ( x ) ((x) & 3)

Macro to extract the file type from a DragonFS file flag.

Parameters

[in] x File flags from DFS entry

Returns: The file type flag

Enumeration Type Documentation

◆ anonymous enum

anonymous enum

Directory walking flags.

Enumerator
WALK_CHDIR	Walk the directory structure for the purpose of changing directories.
WALK_OPEN	Walk the directory structure for the purpose of opening a file or directory.

◆ anonymous enum

anonymous enum

Directory walking return flags.

Enumerator
TYPE_ANY	Return any file or directory found.
TYPE_FILE	Return a file from directory walk.
TYPE_DIR	Return a directory from a directory walk.

Function Documentation

◆ dfs_chdir()

int dfs_chdir ( const char *const path )

Change directories to the specified path.

Supports absolute and relative

Parameters

[in] path Relative or absolute path to change directories to

Returns: DFS_ESUCCESS on success or a negative value on error.

◆ dfs_dir_findfirst()

int dfs_dir_findfirst	(	const char *const	path,
		char *	buf
	)

Find the first file or directory in a directory listing.

Supports absolute and relative. If the path is invalid, returns a negative DFS_errno. If a file or directory is found, returns the flags of the entry and copies the name into buf.

Parameters

[in]	path	The path to look for files in
[out]	buf	Buffer to place the name of the file or directory found

Returns: The flags (FLAGS_FILE, FLAGS_DIR, FLAGS_EOF) or a negative value on error.

◆ dfs_dir_findnext()

int dfs_dir_findnext ( char * buf )

Find the next file or directory in a directory listing.

Note: Should be called after doing a dfs_dir_findfirst.

Parameters

[out] buf Buffer to place the name of the next file or directory found

Returns: The flags (FLAGS_FILE, FLAGS_DIR, FLAGS_EOF) or a negative value on error.

◆ dfs_open()

int dfs_open ( const char *const path )

Open a file given a path.

Check if we have any free file handles, and if we do, try to open the file specified. Supports absolute and relative paths

Parameters

[in] path Path of the file to open

Returns: A valid file handle to reference the file by or a negative error on failure.

◆ dfs_close()

int dfs_close ( uint32_t handle )

Close an already open file handle.

Parameters

[in] handle A valid file handle as returned from dfs_open.

Returns: DFS_ESUCCESS on success or a negative value on error.

◆ dfs_seek()

int dfs_seek	(	uint32_t	handle,
		int	offset,
		int	origin
	)

Seek to an offset in the file.

Parameters

[in]	handle	A valid file handle as returned from dfs_open.
[in]	offset	A byte offset from the origin to seek from.
[in]	origin	An offset to seek from. Either `SEEK_SET`, `SEEK_CUR` or `SEEK_END`.

Returns: DFS_ESUCCESS on success or a negative value on error.

◆ dfs_tell()

int dfs_tell ( uint32_t handle )

Return the current offset into a file.

Parameters

[in] handle A valid file handle as returned from dfs_open.

Returns: The current byte offset into a file or a negative error on failure.

◆ dfs_read()

int dfs_read	(	void *const	buf,
		int	size,
		int	count,
		uint32_t	handle
	)

Read data from a file.

Parameters

[out]	buf	Buffer to read into
[in]	size	Size of each element to read
[in]	count	Number of elements to read
[in]	handle	A valid file handle as returned from dfs_open.

Returns: The actual number of bytes read or a negative value on failure.

◆ dfs_size()

int dfs_size ( uint32_t handle )

Return the file size of an open file.

Parameters

[in] handle A valid file handle as returned from dfs_open.

Returns: The file size in bytes or a negative value on failure.

◆ dfs_rom_addr()

uint32_t dfs_rom_addr ( const char * path )

Return the physical address of a file (in ROM space)

This function should be used for highly-specialized, high-performance use cases. Using dfs_open / dfs_read is generally acceptable performance-wise, and is easier to use rather than managing direct access to PI space.

Direct access to ROM data must go through io_read or dma_read. Do not dereference directly as the console might hang if the PI is busy.

Parameters

[in] path Name of the file

Returns: A pointer to the physical address of the file body, or 0 if the file was not found.

◆ dfs_eof()

int dfs_eof ( uint32_t handle )

Return whether the end of file has been reached.

Parameters

[in] handle A valid file handle as returned from dfs_open.

Returns: 1 if the end of file is reached, 0 if not, and a negative value on error.

◆ dfs_init()

int dfs_init ( uint32_t base_fs_loc )

Initialize the filesystem.

Given a base offset where the filesystem should be found, this function will initialize the filesystem to read from cartridge space. This function will also register DragonFS with newlib so that standard POSIX/C file operations work with DragonFS, using the "rom:/" prefix".

The function needs to know where the DFS image is located within the cartridge space. To simplify this, you can pass DFS_DEFAULT_LOCATION which tells dfs_init to search for the DFS image by itself, using the rompak TOC (see rompak_internal.h). Most users should use this option.

Otherwise, if the ROM cannot be built with a rompak TOC for some reason, a virtual address should be passed. This is normally 0xB0000000 + the offset used when building your ROM + the size of the header file used (typically 0x1000).

Parameters

[in] base_fs_loc Virtual address in cartridge space at which to find the filesystem, or DFS_DEFAULT_LOCATION to automatically search for the filesystem in the cartridge (using the rompak).

Returns: DFS_ESUCCESS on success or a negative error otherwise.

Files

Data Structures

Macros

Enumerations

Functions

DragonFS Return values

DragonFS file type flags

Detailed Description

Data Structure Documentation

◆ directory_entry

◆ open_file_t

Macro Definition Documentation

◆ DFS_DEFAULT_LOCATION

◆ MAX_FILENAME_LEN

◆ FILETYPE

Enumeration Type Documentation

◆ anonymous enum

◆ anonymous enum

Function Documentation

◆ dfs_chdir()

◆ dfs_dir_findfirst()

◆ dfs_dir_findnext()

◆ dfs_open()

◆ dfs_close()

◆ dfs_seek()

◆ dfs_tell()

◆ dfs_read()

◆ dfs_size()

◆ dfs_rom_addr()

◆ dfs_eof()

◆ dfs_init()