2010/9/10 Gao Hong <[email protected]>:
> I'm glad you reply so quickly,thanks for you advise.
> The prototype is already setup in the function _setup_prototypes
> like this:
>>
>> # int libusb_get_string_descriptor_ascii(libusb_device_handle *dev,
>>
>> # uint8_t desc_index,
>>
>> # unsigned char *data,
>>
>> # int length)
>>
>> lib.libusb_get_string_descriptor_ascii.argtypes = [
>>
>> _libusb_device_handle,
>>
>> c_uint8,
>>
>> POINTER(c_ubyte),
>>
>> c_int
>>
>> ]
>
> So,this is not the point where the error leads to.
> Frankly speaking,I knew nothing about the ctypes,and almost forget
> everything about the the C/C++ programming,the low level debug or C
> programming is too hard for me....
> Here is my script:
>>
>> import usb.core
>
> def InterfaceFilter(dev,ItfClass = 8):
>
> """"""
>
> try:
>
> for cfg in dev:
>
> try:
>
> inners = usb.util.find_descriptor(cfg,find_all = True)
>
> for inner in inners:
>
> if type(inner) == usb.core.Interface:
>
> print 'dev:%s:%s' % (dev,inner.bInterfaceClass)
>
> return inner.bInterfaceClass == ItfClass
>
> except:
>
> False
>
> except:
>
> False
>
> usb_devs = usb.core.find(find_all = True,custom_match = InterfaceFilter)
>
> print usb_devs
>
> for dev in usb_devs:
>
> print dev
>
> print 'Vendor:',dev.idVendor
>
> print 'Product:',dev.idProduct
Ah, now I see what's the problem, internally PyUSB manages device
opening automatically. Try a call to set_configuration at
this point of the code:
dev.set_configuration()
Only to force device opening...
>
> print
> 'Manufacturer:',dev._ctx.backend.get_string_descriptor_ascii(dev._ctx.handle,dev.iManufacturer)
>
> This is the funcition I added to the libusb10.py Class _LibUSB:
>>
>> @methodtrace(_logger)
>>
>>
>> #----------------------------------------------------------------------
>>
>> def get_string_descriptor_ascii(self,dev_handle,desc_index):
>>
>> """Added by GaoHong"""
>>
>> buffer = array.array('B','\x00' * 255)
>>
>> address, length = buffer.buffer_info()
>>
>>
>> _check(_lib.libusb_get_string_descriptor_ascii(dev_handle,desc_index,cast(address,
>> POINTER(c_ubyte)),length))
>>
>> return data
>
> I really not know what to do....
> P.S the code of :
>>
>> def getStringDescriptor(device, index):
>>
>> """
>>
>> """
>>
>> response = device.ctrl_transfer(usb.util.ENDPOINT_IN,
>>
>> usb.legacy.REQ_GET_DESCRIPTOR,
>>
>> (usb.util.DESC_TYPE_STRING << 8) |
>> index,
>>
>> 0, # language id
>>
>> 255) # length
>>
>> # TODO: Refer to 'libusb_get_string_descriptor_ascii' for error
>> handling
>>
>>
>>
>> return response[2:].tostring().decode('utf-16')
>
> Doesn't work on windows7 ,libusb windows backend, raise not implemtented
> error,I don't know why/
> 2010/9/10 Wander Lairson <[email protected]>
>>
>> > Hello wander.lairson:
>> > First of all,thanks for your contribution for
>> > the opensource community
>> > and the work for libusb, I appricate it very much.
>> > Currently I want to fetch the serial number of the massive storage
>> > device,which need the string descriptor. Unfortunately,the python
>> > interface
>> > hasn't wrapped the API yet. I tried to implement it myself and copy some
>> > of
>> > the __read function code. Like this:
>> >>
>> >> def get_string_descriptor_ascii(self,dev_handle,desc_index):
>> >>
>> >> """Added by GaoHong"""
>> >>
>> >> buffer = array.array('B','\x00' * 255)
>> >>
>> >> address, length = buffer.buffer_info()
>> >>
>> >>
>> >>
>> >> _check(_lib.libusb_get_string_descriptor_ascii(dev_handle,desc_index,cast(address,
>> >> POINTER(c_ubyte)),length))
>>
>> I am not sure if it is the problem (because I don't know how ctypes
>> pushes arguments in the stack), but if you haven't supplied the
>> function prototype, desc_index will be treated as an integer instead
>> of a 8 bits variable (as in the libusb_get_string_descriptor_ascii
>> interface). You might try this to see if it is a problem:
>>
>>
>> _check(_lib.libusb_get_string_descriptor_ascii(dev_handle,c_uint8(desc_index),cast(address,POINTER(c_ubyte)),length))
>>
>> If not, I am affraid you will have to play with WinDBG to see what's
>> going on. Also, try to write a little C program that call
>> libusb_get_string_descriptor_ascii. I may cut off the possiblity of a
>> bug in libusb.
>>
>> PS: I could debug it for you, but currently I do have no free time for
>> it, I am really sorry.
>>
>> >>
>> >> return data
>> >
>> > but the result always raise WindowsError: exception: access violation
>> > reading 0x00000010
>> > File "E:\my_doc\My Dev\python\GWP 0902\usb_finder.py", line 60, in
>> > <module>
>> > print
>> >
>> > 'Manufacturer:',back.get_string_descriptor_ascii(dev._ctx.handle,dev.iManufacturer)
>> > File "D:\Python26\Lib\site-packages\usb\_debug.py", line 53, in do_trace
>> > return f(*args, **named_args)
>> > File "D:\Python26\Lib\site-packages\usb\backend\libusb10.py", line 593,
>> > in
>> > get_string_descriptor_ascii
>> >
>> > _check(_lib.libusb_get_string_descriptor_ascii(dev_handle,desc_index,cast(address,
>> > POINTER(c_ubyte)),length-1))
>> > I don't know why,the only difference from __read function:
>> >>
>> >> def __read(self, fn, dev_handle, ep, intf, size, timeout):
>> >>
>> >> buffer = array.array('B', '\x00' * size)
>> >>
>> >> address, length = buffer.buffer_info()
>> >>
>> >> transferred = c_int()
>> >>
>> >> _check(fn(dev_handle,
>> >>
>> >> ep,
>> >>
>> >> cast(address, POINTER(c_ubyte)),
>> >>
>> >> length,
>> >>
>> >> byref(transferred),
>> >>
>> >> timeout))
>> >>
>> >> return buffer[:transferred.value]
>> >
>> > is the called function.
>> > Can you tell me why? Thank you very much.
>> > --
>> > It's a long journey to go! :-)
>> > Legend since 1985...
>> >
>>
>>
>>
>> --
>> Best Regards,
>> Wander Lairson Costa
>
>
>
> --
> It's a long journey to go! :-)
> Legend since 1985...
>
--
Best Regards,
Wander Lairson Costa
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