bitfield.py: a python tool which helps thinking in binary:

In [4]: bitfield((1 << 2 | 0x70 | 1<<16-1, 16))
Out[4]:

           12          08          04          00
 1  0  0  0  0  0  0  0  0  1  1  1  0  1  0  0

it's already 2-3 yrs old so may need some improvement.