python保留64位中的最右边60位-类型错误

Question

I have 64 bits integer and I would like to keep right most 60 bits and discard most significant 4 bits. I am using python 3.5.4. Any advice on this problem?

My code is generating type error:

def remove_padding(num):
    num &= num >> 4
    return num

TypeError: unsupported operand type(s) for >>: 'float' and 'int'

Answer 1

If I understand you correctly, you want to keep the 60 least significant bits, right? By rightshifting you would keep the 60 most significant bits.

...6....'....5....'....4....'....3....'....2....'....1....'....0
DDDDKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK   Input
0000KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK   Output

D = Discard, K = Keep

In this case, you just need to And your input with hexadecimal 0FFFFFFFFFFFFFFF :

num &= 0x0FFFFFFFFFFFFFFF