rfc3531-leftmost.py

#!/usr/bin/env python

def leftmost(bits):
    """
    Generate 2-tuples in (ordinal, value) sequence according to the
    order of the "leftmost" scheme specifed in
    
        https://tools.ietf.org/html/rfc3531#section-3.1
        
    for all numbers representable by `bits` bits.
    """
    fmt = '{{:0{bits}b}}'.format(bits=bits)
    for i, p in enumerate(range(2**bits)):
        yield int(''.join(reversed(fmt.format(p))), base=2), i
        
for o, v in sorted(leftmost(5)):
    print("allocate network {} to increment #{}".format(o, v))