Feature or enhancement

Currently, the internal representation of bitfields inctypes is a bit-packed number containing the size and offset. This is rather cumbersome to deal with. (As far as I can tell, the reason is that getters/setters take a single argument. But, these are internal so the signature can be changed.)

My plan is to break the CField size/offset information out into more wordy but explicit fields:

• byte_size &byte_offset, which describe the byte-aligned field within a struct. (This has the same size as the underlying type, and must be fully contained in the struct & readable/writable.)
• bit_size &bit_offset, which identify the bits within that chunk

Also, I intend to add corresponding attributes an the Python level, and expose_CField publicly asctypes.CField, mainly for typing purposes. At this point I don't plan to make the type instantiable.

Something like:

>>>classColor(Structure):...     _fields_= (...         ('red', c_uint8),...         ('green', c_uint8),...         ('blue', c_uint8),...         ('intense', c_bool,1),...         ('blinking', c_bool,1),...    )...>>> Color.red<ctypes.CField 'red' type=c_ubyte, ofs=0, size=1>>>> Color.green.type<class 'ctypes.c_ubyte'>>>> Color.blue.byte_offset2>>> Color.intense<ctypes.CField 'intense' type=c_bool, ofs=3, bit_size=1, bit_offset=0>>>> Color.blinking.bit_offset1

Linked PRs

• gh-128715: Expose ctypes.CField, with info attributes #128950
• gh-128715: CTypeField: Put intness, signedness and pointerness in flags #138541