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Public Member Functions | Static Public Member Functions
ExhaustibleBlockDevice Class Reference

Heap backed block device which simulates failures. More...

#include <ExhaustibleBlockDevice.h>

Inheritance diagram for ExhaustibleBlockDevice:
BlockDevice

Public Member Functions

 ExhaustibleBlockDevice (BlockDevice *bd, uint32_t erase_cycles)
 Lifetime of the block device. More...
 
uint32_t get_erase_cycles (bd_addr_t addr) const
 Get the number of erase cycles remaining on a block. More...
 
void set_erase_cycles (bd_addr_t addr, uint32_t cycles)
 Set the number of erase cycles before failure. More...
 
virtual int init ()
 Initialize a block device. More...
 
virtual int deinit ()
 Deinitialize a block device. More...
 
virtual int sync ()
 Ensure data on storage is in sync with the driver. More...
 
virtual int read (void *buffer, bd_addr_t addr, bd_size_t size)
 Read blocks from a block device. More...
 
virtual int program (const void *buffer, bd_addr_t addr, bd_size_t size)
 Program blocks to a block device. More...
 
virtual int erase (bd_addr_t addr, bd_size_t size)
 Erase blocks on a block device. More...
 
virtual bd_size_t get_read_size () const
 Get the size of a readable block. More...
 
virtual bd_size_t get_program_size () const
 Get the size of a programmable block. More...
 
virtual bd_size_t get_erase_size () const
 Get the size of an erasable block. More...
 
virtual bd_size_t get_erase_size (bd_addr_t addr) const
 Get the size of an erasable block given address. More...
 
virtual int get_erase_value () const
 Get the value of storage when erased. More...
 
virtual bd_size_t size () const
 Get the total size of the underlying device. More...
 
virtual const char * get_type () const
 Get the BlockDevice class type. More...
 
virtual int trim (bd_addr_t addr, bd_size_t size)
 Mark blocks as no longer in use. More...
 
bool is_valid_read (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block read validity. More...
 
bool is_valid_program (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block program validity. More...
 
bool is_valid_erase (bd_addr_t addr, bd_size_t size) const
 Convenience function for checking block erase validity. More...
 

Static Public Member Functions

static BlockDeviceget_default_instance ()
 Return the default block device. More...
 

Detailed Description

Heap backed block device which simulates failures.

Similar to heap block device but sectors wear out and are no longer programmable after a configurable number of cycles.

Definition at line 39 of file ExhaustibleBlockDevice.h.

Constructor & Destructor Documentation

ExhaustibleBlockDevice ( BlockDevice bd,
uint32_t  erase_cycles 
)

Lifetime of the block device.

Parameters
bdBlock device to back the ExhaustibleBlockDevice
erase_cyclesNumber of erase cycles before failure

Member Function Documentation

virtual int deinit ( )
virtual

Deinitialize a block device.

Returns
0 on success or a negative error code on failure

Implements BlockDevice.

virtual int 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.

static BlockDevice* get_default_instance ( )
staticinherited

Return the default block device.

Returns the default block device based on the configuration JSON. Use the components in target.json or application config to change the default block device.

An application can override all target settings by implementing BlockDevice::get_default_instance() - the default definition is weak, and calls get_target_default_instance().

uint32_t get_erase_cycles ( bd_addr_t  addr) const

Get the number of erase cycles remaining on a block.

Parameters
addrAny address in the block being queried for erase cycles
Returns
Number of erase cycles remaining
virtual bd_size_t get_erase_size ( ) const
virtual

Get the size of an erasable block.

Returns
Size of an erasable block in bytes

Reimplemented from BlockDevice.

virtual bd_size_t 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.

virtual int 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.

virtual bd_size_t get_program_size ( ) const
virtual

Get the size of a programmable block.

Returns
Size of a programmable block in bytes

Implements BlockDevice.

virtual bd_size_t get_read_size ( ) const
virtual

Get the size of a readable block.

Returns
Size of a readable block in bytes

Implements BlockDevice.

virtual const char* get_type ( ) const
virtual

Get the BlockDevice class type.

Returns
A string represent the BlockDevice class type.

Implements BlockDevice.

virtual int init ( )
virtual

Initialize a block device.

Returns
0 on success or a negative error code on failure

Implements BlockDevice.

bool is_valid_erase ( bd_addr_t  addr,
bd_size_t  size 
) const
inherited

Convenience function for checking block erase validity.

Parameters
addrAddress of block to begin erasing
sizeSize to erase in bytes
Returns
True if erase is valid for underlying block device

Definition at line 229 of file BlockDevice.h.

bool is_valid_program ( bd_addr_t  addr,
bd_size_t  size 
) const
inherited

Convenience function for checking block program validity.

Parameters
addrAddress of block to begin writing to
sizeSize to write in bytes
Returns
True if program is valid for underlying block device

Definition at line 215 of file BlockDevice.h.

bool is_valid_read ( bd_addr_t  addr,
bd_size_t  size 
) const
inherited

Convenience function for checking block read validity.

Parameters
addrAddress of block to begin reading from
sizeSize to read in bytes
Returns
True if read is valid for underlying block device

Definition at line 201 of file BlockDevice.h.

virtual int 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.

virtual int 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.

void set_erase_cycles ( bd_addr_t  addr,
uint32_t  cycles 
)

Set the number of erase cycles before failure.

Parameters
addrAny address in the block being queried for erase cycles
cyclesErase cycles before the block malfunctions
virtual bd_size_t size ( ) const
virtual

Get the total size of the underlying device.

Returns
Size of the underlying device in bytes

Implements BlockDevice.

virtual int 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.

virtual int trim ( bd_addr_t  addr,
bd_size_t  size 
)
virtualinherited

Mark blocks as no longer in use.

This function provides a hint to the underlying block device that a region of blocks is no longer in use and may be erased without side effects. Erase must still be called before programming, but trimming allows flash-translation-layers to schedule erases when the device is not busy.

Parameters
addrAddress of block to mark as unused
sizeSize to mark as unused in bytes, must be a multiple of the erase block size
Returns
0 on success or a negative error code on failure

Reimplemented in SDBlockDevice, and BufferedBlockDevice.

Definition at line 136 of file BlockDevice.h.

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