diff options
Diffstat (limited to 'docs/library')
| -rw-r--r-- | docs/library/esp32.rst | 6 | ||||
| -rw-r--r-- | docs/library/uos.rst | 100 |
2 files changed, 43 insertions, 63 deletions
diff --git a/docs/library/esp32.rst b/docs/library/esp32.rst index a593965ae2..68379624e6 100644 --- a/docs/library/esp32.rst +++ b/docs/library/esp32.rst @@ -56,10 +56,14 @@ This class gives access to the partitions in the device's flash memory. Returns a 6-tuple ``(type, subtype, addr, size, label, encrypted)``. .. method:: Partition.readblocks(block_num, buf) +.. method:: Partition.readblocks(block_num, buf, offset) .. method:: Partition.writeblocks(block_num, buf) +.. method:: Partition.writeblocks(block_num, buf, offset) .. method:: Partition.ioctl(cmd, arg) - These methods implement the block protocol defined by :class:`uos.AbstractBlockDev`. + These methods implement the simple and :ref:`extended + <block-device-interface>` block protocol defined by + :class:`uos.AbstractBlockDev`. .. method:: Partition.set_boot() diff --git a/docs/library/uos.rst b/docs/library/uos.rst index d8d8b7a972..84d341ac21 100644 --- a/docs/library/uos.rst +++ b/docs/library/uos.rst @@ -178,6 +178,35 @@ represented by VFS classes. Build a FAT filesystem on *block_dev*. +.. class:: VfsLfs1(block_dev) + + Create a filesystem object that uses the `littlefs v1 filesystem format`_. + Storage of the littlefs filesystem is provided by *block_dev*, which must + support the :ref:`extended interface <block-device-interface>`. + Objects created by this constructor can be mounted using :func:`mount`. + + See :ref:`filesystem` for more information. + + .. staticmethod:: mkfs(block_dev) + + Build a Lfs1 filesystem on *block_dev*. + +.. class:: VfsLfs2(block_dev) + + Create a filesystem object that uses the `littlefs v2 filesystem format`_. + Storage of the littlefs filesystem is provided by *block_dev*, which must + support the :ref:`extended interface <block-device-interface>`. + Objects created by this constructor can be mounted using :func:`mount`. + + See :ref:`filesystem` for more information. + + .. staticmethod:: mkfs(block_dev) + + Build a Lfs2 filesystem on *block_dev*. + +.. _littlefs v1 filesystem format: https://github.com/ARMmbed/littlefs/tree/v1 +.. _littlefs v2 filesystem format: https://github.com/ARMmbed/littlefs + Block devices ------------- @@ -187,9 +216,15 @@ implementation of this class will usually allow access to the memory-like functionality a piece of hardware (like flash memory). A block device can be used by a particular filesystem driver to store the data for its filesystem. +.. _block-device-interface: + +Simple and extended interface +............................. + There are two compatible signatures for the ``readblocks`` and ``writeblocks`` methods (see below), in order to support a variety of use cases. A given block -device may implement one form or the other, or both at the same time. +device may implement one form or the other, or both at the same time. The second +form (with the offset parameter) is referred to as the "extended interface". .. class:: AbstractBlockDev(...) @@ -247,64 +282,5 @@ device may implement one form or the other, or both at the same time. (*arg* is unused) - 6 -- erase a block, *arg* is the block number to erase -By way of example, the following class will implement a block device that stores -its data in RAM using a ``bytearray``:: - - class RAMBlockDev: - def __init__(self, block_size, num_blocks): - self.block_size = block_size - self.data = bytearray(block_size * num_blocks) - - def readblocks(self, block_num, buf): - for i in range(len(buf)): - buf[i] = self.data[block_num * self.block_size + i] - - def writeblocks(self, block_num, buf): - for i in range(len(buf)): - self.data[block_num * self.block_size + i] = buf[i] - - def ioctl(self, op, arg): - if op == 4: # get number of blocks - return len(self.data) // self.block_size - if op == 5: # get block size - return self.block_size - -It can be used as follows:: - - import uos - - bdev = RAMBlockDev(512, 50) - uos.VfsFat.mkfs(bdev) - vfs = uos.VfsFat(bdev) - uos.mount(vfs, '/ramdisk') - -An example of a block device that supports both signatures and behaviours of -the :meth:`readblocks` and :meth:`writeblocks` methods is:: - - class RAMBlockDev: - def __init__(self, block_size, num_blocks): - self.block_size = block_size - self.data = bytearray(block_size * num_blocks) - - def readblocks(self, block, buf, offset=0): - addr = block_num * self.block_size + offset - for i in range(len(buf)): - buf[i] = self.data[addr + i] - - def writeblocks(self, block_num, buf, offset=None): - if offset is None: - # do erase, then write - for i in range(len(buf) // self.block_size): - self.ioctl(6, block_num + i) - offset = 0 - addr = block_num * self.block_size + offset - for i in range(len(buf)): - self.data[addr + i] = buf[i] - - def ioctl(self, op, arg): - if op == 4: # block count - return len(self.data) // self.block_size - if op == 5: # block size - return self.block_size - if op == 6: # block erase - return 0 +See :ref:`filesystem` for example implementations of block devices using both +protocols. |