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length is 8 bits, will be extracted - effectively, this will access least-significant byte of
UINT16
.
Note that bitfield operations are independent of target byte endianness, in particular,
example above will access least-significant byte of
UINT16
in both little- and big-endian
structures. But it depends on the least significant bit being numbered 0. Some targets may
use different numbering in their native ABI, but
uctypes
always uses normalised numbering
described above.
Module Contents
class uctypes.struct(addr, descriptor, layout_type=NATIVE)
Instantiate a "foreign data structure" object based on structure address in memory,
descriptor (encoded as a dictionary), and layout type (see below).
uctypes.LITTLE_ENDIAN
Layout type for a little-endian packed structure. (Packed means that every field occupies
exactly as many bytes as defined in the descriptor, i.e. the alignment is 1).
uctypes.BIG_ENDIAN
Layout type for a big-endian packed structure.
uctypes.NATIVE
Layout type for a native structure - with data endianness and alignment conforming to the
ABI of the system on which MicroPython runs.
uctypes.sizeof(struct)
Return size of data structure in bytes. Argument can be either structure class or specific
instantiated structure object (or its aggregate field).
uctypes.addressof(obj)
Return address of an object. Argument should be bytes,
bytearray
or other object
supporting buffer protocol (and address of this buffer is what actually returned).
uctypes.bytes_at(addr, size)
Capture memory at the given address and size as bytes object. As bytes object is
immutable, memory is actually duplicated and copied into bytes object, so if memory
contents change later, created object retains original value.
5.3.2 uctypes
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