Portable hash in Cython

portable_hash.pyx

from libc.stdint cimport int64_t
cdef tuple_hash(obj):
    cdef int64_t mul = 1000003, l = len(obj), value = 0x345678, v
    for i in obj:
        l -= 1
        v = portable_hash(i)
        if v == -1:
            return -1
        value = (value ^ v) * mul
        mul += <int64_t> (82520 + l * 2)
    value += 97531
    if value == -1:
        value = -2
    return value

cdef string_hash(obj):
    cdef char* s = obj
    cdef char c
    cdef int64_t l = len(obj), value
    if l == 0:
        return 0
    value = s[0] << 7
    for c in s:
        value = (1000003 * value) ^ c

    value ^= l
    if value == -1:
        value = -2
    return value

def portable_hash(obj):
    if obj is None:
        return 1315925605
    elif isinstance(obj, basestring):
        return string_hash(obj)
    elif isinstance(obj, tuple):
        return tuple_hash(obj)
    elif isinstance(obj, (int, long, float)):
        return hash(obj)
    else:
        raise TypeError('unhashable by portable_hash')