Addition of numbers via Bits object?

[5hayanB]

There is already the special method __add__() in the Bits class which is used to concatenate the bitstrings of its operands. But is there a way to do arithmetic addition of the values themselves that the Bits objects represent?

[scott-griffiths]

Hi. Yes you can modify an interpretation of a BitArray object to do what I think you're trying to do. Note that this doesn't work for a Bits class as that's immutable.

>>> a = BitArray(uint=5, length=10)
>>> a
BitArray('0b0000000101')
>>> a.u
5
>>> a.u += 11
>>> a.u
16
>>> a
BitArray('0b0000010000')

The line a.u += 11 gets the unsigned integer interpretation of the binary data, adds eleven to it, then resets the data with the new value (keeping the length the same).

Hope that helps.

[scott-griffiths]

Oh, and you can also do this with the Array class, which might be what you need:

>>> a = Array('u10', [1, 2, 3])
>>> a
Array('uint10', [1, 2, 3])
>>> a.tolist()
[1, 2, 3]
>>> a += 5
>>> a
Array('uint10', [6, 7, 8])
>>> a.tolist()
[6, 7, 8]
>>> a.tobytes()
b'\x01\x80p '

This is storing 3 unsigned integers in 30 bits of data and manipulating their values.