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Mempak Filesystem Routines
[Controller Subsystem]

Managed mempak interface. More...

Data Structures

struct  entry_structure
 Structure representing a save entry in a mempak. More...

Files

file  mempak.c
 

Mempak Filesystem Routine.


file  mempak.h
 

Mempak Filesystem Routines.


Defines

#define MEMPAK_BLOCK_SIZE   256
 Size in bytes of a Mempak block.

Typedefs

typedef struct entry_structure entry_structure_t
 Structure representing a save entry in a mempak.

Functions

int read_mempak_sector (int controller, int sector, uint8_t *sector_data)
 Read a sector from a mempak.
int write_mempak_sector (int controller, int sector, uint8_t *sector_data)
 Write a sector to a mempak.
int validate_mempak (int controller)
 Return whether a mempak is valid.
int get_mempak_entry (int controller, int entry, entry_structure_t *entry_data)
 Read an entry on a mempak.
int get_mempak_free_space (int controller)
 Return the number of free blocks on a mempak.
int format_mempak (int controller)
 Format a mempak.
int read_mempak_entry_data (int controller, entry_structure_t *entry, uint8_t *data)
 Read the data associated with an entry on a mempak.
int write_mempak_entry_data (int controller, entry_structure_t *entry, uint8_t *data)
 Write associated data to a mempak entry.
int delete_mempak_entry (int controller, entry_structure_t *entry)
 Delete a mempak entry and associated data.

Inode values



#define BLOCK_EMPTY   0x03
 This block is empty.
#define BLOCK_LAST   0x01
 This is the last block in the note.
#define BLOCK_VALID_FIRST   0x05
 First valid block that can contain user data.
#define BLOCK_VALID_LAST   0x7F
 Last valid block that can contain user data.

Detailed Description

Managed mempak interface.

The mempak system is a subsystem of the Controller Subsystem. Before attempting to read from or write to a mempak, be sure you have initialized the controller system with controller_init and verified that you have a mempak in the correct controller using identify_accessory.

To read and write to the mempak in an organized way compatible with official software, first check that the mempak is valid using validate_mempak. If the mempack is invalid, it will need to be formatted using format_mempak. Once the mempak is considered valid, existing notes can be enumerated using get_mempak_entry. To read the data associated with a note, use read_mempak_entry_data. To write a new note to the mempak, use write_mempak_entry_data. Note that there is no append functionality so if a note is being updated, ensure you have deleted the old note first using delete_mempak_entry. Code should be careful to check how many blocks are free before writing using get_mempak_free_space.


Function Documentation

int delete_mempak_entry ( int  controller,
entry_structure_t entry 
)

Delete a mempak entry and associated data.

Given a valid mempak entry fetched by get_mempak_entry, removes the entry and frees all associated blocks.

Parameters:
[in] controller The controller (0-3) to delete the note from
[in] entry The entry structure that is to be deleted from the mempak
Return values:
0 if the entry was deleted successfully
-1 if the entry was invalid
-2 if the mempak was bad or not present
int format_mempak ( int  controller  ) 

Format a mempak.

Formats a mempak. Should only be done to wipe a mempak or to initialize the filesystem in case of a blank or corrupt mempak.

Parameters:
[in] controller The controller (0-3) to format the mempak on
Return values:
0 if the mempak was formatted successfully
-2 if the mempak was not present or couldn't be formatted
int get_mempak_entry ( int  controller,
int  entry,
entry_structure_t entry_data 
)

Read an entry on a mempak.

Given an entry index (0-15), return the entry as found on the mempak. If the entry is blank or invalid, the valid flag is cleared.

Parameters:
[in] controller The controller (0-3) from which the entry should be read
[in] entry The entry index (0-15) to read
[out] entry_data Structure containing information on the entry
Return values:
0 if the entry was read successfully
-1 if the entry is out of bounds or entry_data is null
-2 if the mempak is bad or not present
int get_mempak_free_space ( int  controller  ) 

Return the number of free blocks on a mempak.

Note that a block is identical in size to a sector. To calculate the number of bytes free, multiply the return of this function by MEMPAK_BLOCK_SIZE.

Parameters:
[in] controller The controller (0-3) to read the free space from
Returns:
The number of blocks free on the memory card or a negative number on failure
int read_mempak_entry_data ( int  controller,
entry_structure_t entry,
uint8_t *  data 
)

Read the data associated with an entry on a mempak.

Given a valid mempak entry fetched by get_mempak_entry, retrieves the contents of the entry. The calling function must ensure that enough room is available in the passed in buffer for the entire entry. The entry structure itself contains the number of blocks used to store the data which can be multiplied by MEMPAK_BLOCK_SIZE to calculate the size of the buffer needed.

Parameters:
[in] controller The controller (0-3) to read the entry data from
[in] entry The entry structure associated with the data to be read. An entry structure can be fetched based on index using get_mempak_entry
[out] data The data associated with an entry
Return values:
0 if the entry was successfully read
-1 if input parameters were out of bounds or the entry was corrupted somehow
-2 if the mempak was not present or bad
-3 if the data couldn't be read
int read_mempak_sector ( int  controller,
int  sector,
uint8_t *  sector_data 
)

Read a sector from a mempak.

This will read a sector from a mempak. Sectors on mempaks are always 256 bytes in size.

Parameters:
[in] controller The controller (0-3) to read a sector from
[in] sector The sector (0-127) to read from
[out] sector_data Buffer to place 256 read bytes of data
Return values:
0 if reading was successful
-1 if the sector was out of bounds or sector_data was null
-2 if there was an error reading part of a sector
int validate_mempak ( int  controller  ) 

Return whether a mempak is valid.

This function will return whether the mempak in a particular controller is formatted and valid.

Parameters:
[in] controller The controller (0-3) to validate
Return values:
0 if the mempak is valid and ready to be used
-2 if the mempak is not present or couldn't be read
-3 if the mempak is bad or unformatted
int write_mempak_entry_data ( int  controller,
entry_structure_t entry,
uint8_t *  data 
)

Write associated data to a mempak entry.

Given a mempak entry structure with a valid region, name and block count, writes the entry and associated data to the mempak. This function will not overwrite any existing user data. To update an existing entry, use delete_mempak_entry followed by write_mempak_entry_data with the same entry structure.

Parameters:
[in] controller The controller (0-3) to write the entry and data to
[in] entry The entry structure containing a region, name and block count
[in] data The associated data to write to to the created entry
Return values:
0 if the entry was created and written successfully
-1 if the parameters were invalid or the note has no length
-2 if the mempak wasn't present or was bad
-3 if there was an error writing to the mempak
-4 if there wasn't enough space to store the note
-5 if there is no room in the TOC to add a new entry
int write_mempak_sector ( int  controller,
int  sector,
uint8_t *  sector_data 
)

Write a sector to a mempak.

This will write a sector to a mempak. Sectors on mempaks are always 256 bytes in size.

Parameters:
[in] controller The controller (0-3) to write a sector to
[in] sector The sector (0-127) to write to
[out] sector_data Buffer containing 256 bytes of data to write to sector
Return values:
0 if writing was successful
-1 if the sector was out of bounds or sector_data was null
-2 if there was an error writing part of a sector
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