Das deutsche Python-Forum

Code: Alles auswählen

buffer(struc)[:]

Code: Alles auswählen

buffer(struct)[0:len(raw)] = raw #geht nicht (python verabschiedet sich)

Code: Alles auswählen

class PTP_USB_Bulk_Params(ctypes.Structure):
    _fields_ = [
        ('param1', ctypes.c_uint),
        ('param2', ctypes.c_uint),
        ('param3', ctypes.c_uint),
        ('param4', ctypes.c_uint),
        ('param5', ctypes.c_uint),
               ]

PTP_USB_BULK_HS_MAX_PACKET_LEN = 4096
PTP_USB_BULK_HDR_LEN = (2*ctypes.sizeof(ctypes.c_uint)+2*ctypes.sizeof(ctypes.c_ushort))
PTP_USB_BULK_PAYLOAD_LEN = (PTP_USB_BULK_HS_MAX_PACKET_LEN-PTP_USB_BULK_HDR_LEN)
PTP_USB_BULK_REQ_LEN = (PTP_USB_BULK_HDR_LEN+5*ctypes.sizeof(ctypes.c_uint))

class PTP_USB_Bulk_Payload(ctypes.Union):
    _fields_ = [
        ('params', PTP_USB_Bulk_Params),
        ('data', ctypes.c_char*PTP_USB_BULK_PAYLOAD_LEN),
               ]

class PTP_USB_Bulk_Container(ctypes.Structure):
    _fields_ = [
        ('length', ctypes.c_uint),
        ('type', ctypes.c_ushort),
        ('code', ctypes.c_ushort),
        ('trans_id', ctypes.c_uint),
        ('payload', PTP_USB_Bulk_Payload)
               ]

Code: Alles auswählen

import ctypes

CharPtr = ctypes.POINTER(ctypes.c_char)
CharPtrPtr = ctypes.POINTER(CharPtr)
    
Py_ssize_t = ctypes.c_int
Py_ssize_t_Ptr = ctypes.POINTER(Py_ssize_t)
    
PyString_AsStringAndSize = ctypes.pythonapi.PyString_AsStringAndSize
PyString_AsStringAndSize.restype = ctypes.c_int
PyString_AsStringAndSize.argtypes = [ctypes.py_object, CharPtrPtr, Py_ssize_t_Ptr]

def from_string(s, c_obj):
    """Set contents of ctypes object c_obj to that of string s

    If the length of s is not the size of c_obj a SizeError
    exception is raised."""
    try:
        c_cp = CharPtr()
        c_sz = Py_ssize_t(0)
        PyString_AsStringAndSize(s, ctypes.byref(c_cp), ctypes.byref(c_sz))
        sz = c_sz.value
        if ctypes.sizeof(c_obj) != sz:
            raise "String and ctype object are different sizes [%d] [%d]"%(ctypes.sizeof(c_obj),sz)
        ctypes.memmove(ctypes.addressof(c_obj), c_cp, sz)
    finally:
        del c_cp  # Keep off traceback.