appengine/third_party/python-libusb1/README.rst

Pure-python wrapper for libusb-1.0

Supports all transfer types, both in synchronous and asynchronous mode.

Home: http://github.com/vpelletier/python-libusb1

PyPI: http://pypi.python.org/pypi/libusb1

.. role:: c_code(code)
  :language: c

.. role:: python_code(code)
  :language: python

Dependencies
============

- CPython_ 2.7+ or 3.4+, pypy_ 2.0+. Older versions may work, but are not
  recommended as there is no automated regression testing set up for them.

- libusb-1.0_ or libusbx_

Supported OSes
==============

python-libusb1 can be expected to work on:

- GNU/Linux

- Windows [#]_ native dll or via Cygwin_

- OSX [#]_ via MacPorts_, Fink_ or Homebrew_

- FreeBSD (including Debian GNU/kFreeBSD)

- OpenBSD

.. [#] Beware of libusb-win32, which implements 0.1 API, not 1.0 .

.. [#] Beware of possible lack of select.poll if you want to use asynchronous
       API.

Installation
============

Releases from PyPI, with name *libusb1*. Installing from command line::

    $ pip libusb1

or::

    $ easy_install libusb1

Latest version from source tree::

    $ git clone https://github.com/vpelletier/python-libusb1.git
    $ cd python-libusb1
    $ python setup.py install

Usage
=====

Finding a device and gaining exclusive access:

.. code:: python

    import usb1
    with usb1.USBContext() as context:
        handle = context.openByVendorIDAndProductID(
            VENDOR_ID,
            PRODUCT_ID,
            skip_on_error=True,
        )
        if handle is None:
            # Device not present, or user is not allowed to access device.
        with handle.claimInterface(INTERFACE):
            # Do stuff with endpoints on claimed interface.

Synchronous I/O:

.. code:: python

    while True:
        data = handle.bulkRead(ENDPOINT, BUFFER_SIZE)
        # Process data...

Asynchronous I/O, with more error handling:

.. code:: python

    def processReceivedData(transfer):
        if transfer.getStatus() != usb1.TRANSFER_COMPLETED:
            # Transfer did not complete successfully, there is no data to read.
            # This example does not resubmit transfers on errors. You may want
            # to resubmit in some cases (timeout, ...).
            return
        data = handle.getBuffer()[:transfer.getActualLength()]
        # Process data...
        # Resubmit transfer once data is processed.
        transfer.submit()

    # Build a list of transfer objects and submit them to prime the pump.
    transfer_list = []
    for _ in xrange(TRANSFER_COUNT):
        transfer = handle.getTransfer()
        transfer.setBulk(
            usb1.ENDPOINT_IN | ENDPOINT,
            BUFFER_SIZE,
            callback=processReceivedData,
        )
        transfer.submit()
        transfer_list.append(transfer)
    # Loop as long as there is at least one submitted transfer.
    while any(x.isSubmitted() for x in reader_list):
        try:
            context.handleEvents()
        except usb1.USBErrorInterrupted:
            pass

For more, see the ``example`` directory.

Documentation
=============

python-libusb1 main documentation is accessible with python's standard
``pydoc`` command.

python-libusb1 follows libusb-1.0 documentation as closely as possible, without
taking decisions for you. Thanks to this, python-libusb1 does not need to
duplicate the nice existing `libusb1.0 documentation`_.

Some description is needed though on how to jump from libusb-1.0 documentation
to python-libusb1, and vice-versa:

``usb1`` module groups libusb-1.0 functions as class methods. The first
parameter (when it's a ``libusb_...`` pointer) defined the class the fonction
belongs to. For example:

- :c_code:`int libusb_init (libusb_context **context)` becomes USBContext class
  constructor, :python_code:`USBContext.__init__(self)`

- :c_code:`ssize_t libusb_get_device_list (libusb_context *ctx,
  libusb_device ***list)` becomes an USBContext method, returning a
  list of USBDevice instances, :python_code:`USBDevice.getDeviceList(self)`

- :c_code:`uint8_t libusb_get_bus_number (libusb_device *dev)` becomes an
  USBDevice method, :python_code:`USBDevice.getBusNumber(self)`

Error statuses are converted into :python_code:`usb1.USBError` exceptions, with
status as ``value`` instance property.

``usb1`` module also defines a few more functions and classes, which are
otherwise not so convenient to call from Python: the event handling API needed
by async API.

History
=======

0.0.1
-----

Initial release

0.1.1
-----

Massive rework of usb1.py, making it more python-ish and fixing some
memory leaks.

0.1.2
-----

Deprecate "transfer" constructor parameter to allow instance reuse.

0.1.3
-----

Some work on isochronous "in" transfers. They don't raise exceptions anymore,
but data validity and python-induced latency impact weren't properly checked.

0.2.0
-----

Fix asynchronous configuration transfers.

Stand-alone polling thread for multi-threaded apps.

More libusb methods exposed on objects, including ones not yet part of
released libusb versions (up to their commit 4630fc2).

2to3 friendly.

Drop deprecated USBDevice.reprConfigurations method.

0.2.1
-----

Add FreeBSD support.

0.2.2
-----

Add Cygwin support.

OpenBSD support checked (no change).

0.2.3
-----

Add fink and homebrew support on OSX.

Drop PATH_MAX definition.

Try harder when looking for libusb.

1.0.0
-----

Fix FreeBSD ABI compatibility.

Easier to list connected devices.

Easier to terminate all async transfers for clean exit.

Fix few segfault causes.

pypy support.

1.1.0
-----

Descriptor walk API documented.

Version and capability APIs exposed.

Some portability fixes (OSes, python versions).

Isochronous transfer refuses to round transfer size.

Better exception handling in enumeration.

Add examples.

Better documentation.

1.2.0
-----

Wrap hotplug API.

Wrap port number API.

Wrap kernel auto-detach API.

Drop wrapper for libusb_strerror, with compatibility place-holder.

Add a few new upstream enum values.

1.3.0
-----

**Backward-incompatible change**: Enum class now affects caller's local scope,
not its global scope. This should not be of much importance, as:

- This class is probably very little used outside libusb1.py

- This class is probably mostly used at module level, where locals == globals.

  It is possible to get former behaviour by providing the new ``scope_dict``
  parameter to ``Enum`` constructor::

    SOME_ENUM = libusb1.Enum({...}, scope_dict=globals())

Improve start-up time on CPython by not importing standard ``inspect`` module.

Fix some more USBTransfer memory leaks.

Add Transfer.iterISO for more efficient isochronous reception.

1.3.1
-----

Fixed USBContext.waitForEvent.

Fix typo in USBInterfaceSetting.getClassTuple method name. Backward
compatibility preserved.

Remove globals accesses from USBDeviceHandle destructor.

Assorted documentation improvements.

1.3.2
-----

Made USBDevice instances hashable.

Relaxed licensing by moving from GPL v2+ to LGPL v2.1+, for consistency with
libusb1.

1.4.0
-----

Reduce (remove ?) the need to import libusb1 module by exposing USBError and
constants in usb1 module.

Fix libusb1.LIBUSB_ENDPOINT_ENDPOINT_MASK and
libusb1.LIBUSB_ENDPOINT_DIR_MASK naming.

Fix pydoc appearance of several USBContext methods.

Define exception classes for each error values.

1.4.1
-----

Fix wheel generation (``python3 setup.py bdist_wheel``).

1.5.0
-----

controlWrite, bulkWrite and interruptWrite now reject (with TypeError) numeric
values for ``data`` parameter.

Fix libusb1.REQUEST_TYPE_* names (were TYPE_*). Preserve backward
compatibility.

Add USBContext.getDeviceIterator method.

Rename USBContext.exit as USBContext.close for consistency with other USB*
classes. Preserve backward compatibility.

Make USBDeviceHandle.claimInterface a context manager, for easier interface
releasing.

1.5.1
-----

Introduce USBPollerThread.stop .

Fix USBDeviceHandle.getSupportedLanguageList bug when running under python 3.
While fixing this bug it was realised that this method returned ctypes objects.
This was not intended, and it now returns regular integers.

.. _CPython: http://www.python.org/

.. _pypy: http://pypy.org/

.. _Cygwin: https://www.cygwin.com/

.. _MacPorts: https://www.macports.org/

.. _Fink: http://www.finkproject.org/

.. _Homebrew: http://brew.sh/

.. _libusb-1.0: http://www.libusb.org/wiki/libusb-1.0

.. _libusbx: http://libusb.info/

.. _libusb1.0 documentation: http://libusb.org/static/api-1.0/