[docs]def is_power_of_2(num):
"""
Returns whether num is a power of two or not
:param num: an integer positive number
:return: True if num is a power of 2, False otherwise
"""
return num != 0 and ((num & (num - 1)) == 0)
[docs]def next_power_of_2(x):
"""
Returns the first power of two >= x, so f(2) = 2, f(127) = 128, f(65530) = 65536
:param x:
:return:
"""
# NOTES for this black magic:
# * .bit_length returns the number of bits necessary to represent self in binary
# * x << y means 1 with the bits shifted to the left by y, which is the same as multiplying x by 2**y (but faster)
return 1 << (x - 1).bit_length()