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"arr" : (uctypes.ARRAY | 0 , uctypes.UINT8 | 2 ),
I.e. value is a 2-tuple, first element of which is ARRAY flag OR-ed with offset, and second is
scalar element type OR-ed number of elements in array.
Arrays of Aggregate Types:
"arr2" : (uctypes.ARRAY | 0 , 2 , { "b" : uctypes.UINT8 | 0 }),
I.e. value is a 3-tuple, first element of which is ARRAY flag OR-ed with offset, second is a
number of elements in array, and third is descriptor of element type.
Pointer to a primitive type:
"ptr" : (uctypes.PTR | 0 , uctypes.UINT8),
I.e. value is a 2-tuple, first element of which is PTR flag OR-ed with offset, and second is
scalar element type.
Pointer to an aggregate type:
"ptr2" : (uctypes.PTR | 0 , { "b" : uctypes.UINT8 | 0 }),
I.e. value is a 2-tuple, first element of which is PTR flag OR-ed with offset, second is
descriptor of type pointed to.
Bitfields:
"bitf0" : uctypes.BFUINT16 | 0 | 0 << uctypes.BF_POS | 8 << uctypes.BF_LEN,
I.e. value is type of scalar value containing given bitfield (typenames are similar to scalar
types, but prefixes with "BF"), OR-ed with offset for scalar value containing the bitfield, and
further OR-ed with values for bit offset and bit length of the bitfield within scalar value,
shifted by BF_POS and BF_LEN positions, respectively. Bitfield position is counted from the
least significant bit, and is the number of right-most bit of a field (in other words, it’s a
number of bits a scalar needs to be shifted right to extra the bitfield).
In the example above, first
UINT16
value will be extracted at offset 0 (this detail may be
important when accessing hardware registers, where particular access size and alignment
are required), and then bitfield whose rightmost bit is least-significant bit of this
UINT16
, and
5.3.2 uctypes
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