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Public Member Functions | Static Public Member Functions | Protected Attributes
MBRBlockDevice Class Reference

#include <MBRBlockDevice.h>

Inheritance diagram for MBRBlockDevice:
BlockDevice

Public Member Functions

 MBRBlockDevice (BlockDevice *bd, int part)
 
virtual ~MBRBlockDevice ()
 
virtual int init ()
 
virtual int deinit ()
 
virtual int sync ()
 
virtual int read (void *buffer, bd_addr_t addr, bd_size_t size)
 
virtual int program (const void *buffer, bd_addr_t addr, bd_size_t size)
 
virtual int erase (bd_addr_t addr, bd_size_t size)
 
virtual bd_size_t get_read_size () const
 
virtual bd_size_t get_program_size () const
 
virtual bd_size_t get_erase_size () const
 
virtual bd_size_t get_erase_size (bd_addr_t addr) const
 
virtual int get_erase_value () const
 
virtual bd_size_t size () const
 
virtual bd_addr_t get_partition_start () const
 
virtual bd_addr_t get_partition_stop () const
 
virtual uint8_t get_partition_type () const
 
virtual int get_partition_number () const
 
- Public Member Functions inherited from BlockDevice
virtual ~BlockDevice ()
 
virtual int trim (bd_addr_t addr, bd_size_t size)
 
bool is_valid_read (bd_addr_t addr, bd_size_t size) const
 
bool is_valid_program (bd_addr_t addr, bd_size_t size) const
 
bool is_valid_erase (bd_addr_t addr, bd_size_t size) const
 

Static Public Member Functions

static int partition (BlockDevice *bd, int part, uint8_t type, bd_addr_t start)
 
static int partition (BlockDevice *bd, int part, uint8_t type, bd_addr_t start, bd_addr_t stop)
 

Protected Attributes

BlockDevice_bd
 
bd_size_t _offset
 
bd_size_t _size
 
uint8_t _type
 
uint8_t _part
 
uint32_t _init_ref_count
 

Detailed Description

Block device for managing a Master Boot Record https://en.wikipedia.org/wiki/Master_boot_record

Here is an example of partitioning a heap backed block device

#include "mbed.h"
#include "HeapBlockDevice.h"
#include "MBRBlockDevice.h"
// Create a block device with 64 blocks of size 512
HeapBlockDevice mem(64*512, 512);
// Partition into two partitions with ~half the blocks
MBRBlockDevice::partition(&mem, 1, 0x83, 0*512, 32*512);
MBRBlockDevice::partition(&mem, 2, 0x83, 32*512);
// Create a block device that maps to the first 32 blocks (excluding MBR block)
MBRBlockDevice part1(&mem, 1);
// Create a block device that maps to the last 32 blocks
MBRBlockDevice part2(&mem, 2);

Here is a more realistic example where the MBRBlockDevice is used to partition a region of space on an SD card. When plugged into a computer, the partitions will be recognized appropriately.

#include "mbed.h"
#include "SDBlockDevice.h"
#include "MBRBlockDevice.h"
#include "FATFileSystem.h"
// Create an SD card
SDBlockDevice sd(s0, s1, s2, s3);
// Create a partition with 1 GB of space
MBRBlockDevice::partition(&sd, 1, 0x83, 0, 1024*1024);
// Create the block device that represents the partition
MBRBlockDevice part1(&sd, 1);
// Format the partition with a FAT filesystem
// Create the FAT filesystem instance, files can now be written to
// the FAT filesystem in partition 1
FATFileSystem fat("fat", &part1);
Note
The MBR partition table is relatively limited:
  • At most 4 partitions are supported
  • Extended partitions are currently not supported and will error during init

Constructor & Destructor Documentation

MBRBlockDevice::MBRBlockDevice ( BlockDevice bd,
int  part 
)

Lifetime of the block device

Parameters
bdBlock device to back the MBRBlockDevice
partPartition to use, 1-4
virtual MBRBlockDevice::~MBRBlockDevice ( )
inlinevirtual

Lifetime of the block device

Member Function Documentation

int MBRBlockDevice::deinit ( )
virtual

Deinitialize a block device

Returns
0 on success or a negative error code on failure

Implements BlockDevice.

int MBRBlockDevice::erase ( bd_addr_t  addr,
bd_size_t  size 
)
virtual

Erase blocks on a block device

The state of an erased block is undefined until it has been programmed, unless get_erase_value returns a non-negative byte value

Parameters
addrAddress of block to begin erasing
sizeSize to erase in bytes, must be a multiple of erase block size
Returns
0 on success, negative error code on failure

Reimplemented from BlockDevice.

bd_size_t MBRBlockDevice::get_erase_size ( ) const
virtual

Get the size of an erasable block

Returns
Size of an erasable block in bytes
Note
Must be a multiple of the program size

Reimplemented from BlockDevice.

bd_size_t MBRBlockDevice::get_erase_size ( bd_addr_t  addr) const
virtual

Get the size of an erasable block given address

Parameters
addrAddress within the erasable block
Returns
Size of an erasable block in bytes
Note
Must be a multiple of the program size

Reimplemented from BlockDevice.

int MBRBlockDevice::get_erase_value ( ) const
virtual

Get the value of storage when erased

If get_erase_value returns a non-negative byte value, the underlying storage is set to that value when erased, and storage containing that value can be programmed without another erase.

Returns
The value of storage when erased, or -1 if you can't rely on the value of erased storage

Reimplemented from BlockDevice.

int MBRBlockDevice::get_partition_number ( ) const
virtual

Get the partition number

Returns
The partition number, 1-4
bd_size_t MBRBlockDevice::get_partition_start ( ) const
virtual

Get the offset of the partition on the underlying block device

Returns
Offset of the partition on the underlying device
bd_size_t MBRBlockDevice::get_partition_stop ( ) const
virtual

Get size of partition on underlying block device

Returns
Size of the partition on the underlying device
uint8_t MBRBlockDevice::get_partition_type ( ) const
virtual

Get 8-bit type of the partition

Returns
8-bit type of partition assigned during format
bd_size_t MBRBlockDevice::get_program_size ( ) const
virtual

Get the size of a programmable block

Returns
Size of a programmable block in bytes
Note
Must be a multiple of the read size

Implements BlockDevice.

bd_size_t MBRBlockDevice::get_read_size ( ) const
virtual

Get the size of a readable block

Returns
Size of a readable block in bytes

Implements BlockDevice.

int MBRBlockDevice::init ( )
virtual

Initialize a block device

Returns
0 on success or a negative error code on failure

Implements BlockDevice.

int MBRBlockDevice::partition ( BlockDevice bd,
int  part,
uint8_t  type,
bd_addr_t  start 
)
static

Format the MBR to contain the following partition

Parameters
bdBlock device to partition
partPartition to use, 1-4
type8-bit partition type to identitfy partition's contents
startStart block address to map to block 0 of partition, negative addresses are calculated from the end of the underlying block devices. Block 0 is implicitly ignored from the range to store the MBR.
Returns
0 on success or a negative error code on failure
Note
This is the same as partition(bd, part, type, start, bd->size())
int MBRBlockDevice::partition ( BlockDevice bd,
int  part,
uint8_t  type,
bd_addr_t  start,
bd_addr_t  stop 
)
static

Format the MBR to contain the following partition

Parameters
bdBlock device to partition
partPartition to use, 1-4
type8-bit partition type to identitfy partition's contents
startStart block address to map to block 0 of partition, negative addresses are calculated from the end of the underlying block devices. Block 0 is implicitly ignored from the range to store the MBR.
stopEnd block address to mark the end of the partition, this block is not mapped, negative addresses are calculated from the end of the underlying block device.
Returns
0 on success or a negative error code on failure
int MBRBlockDevice::program ( const void *  buffer,
bd_addr_t  addr,
bd_size_t  size 
)
virtual

Program blocks to a block device

The blocks must have been erased prior to being programmed

Parameters
bufferBuffer of data to write to blocks
addrAddress of block to begin writing to
sizeSize to write in bytes, must be a multiple of program block size
Returns
0 on success, negative error code on failure

Implements BlockDevice.

int MBRBlockDevice::read ( void *  buffer,
bd_addr_t  addr,
bd_size_t  size 
)
virtual

Read blocks from a block device

Parameters
bufferBuffer to read blocks into
addrAddress of block to begin reading from
sizeSize to read in bytes, must be a multiple of read block size
Returns
0 on success, negative error code on failure

Implements BlockDevice.

bd_size_t MBRBlockDevice::size ( ) const
virtual

Get the total size of the underlying device

Returns
Size of the underlying device in bytes

Implements BlockDevice.

int MBRBlockDevice::sync ( )
virtual

Ensure data on storage is in sync with the driver

Returns
0 on success or a negative error code on failure

Reimplemented from BlockDevice.


The documentation for this class was generated from the following files:
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