arraytime.py

import array
import timeit
import numpy
import sys

mask = [0x71, 0x45, 0x54, 0x82]
mask_str = ''.join(chr(m) for m in mask)


def time_numpy(data):
    plen = len(data)
    b = c = ''

    if plen >= 4:
        dtype=numpy.dtype('<u4')
        if sys.byteorder == 'big':
            dtype = dtype.newbyteorder('>')

        mask = numpy.fromstring(mask_str, dtype)
        data = numpy.frombuffer(data, dtype, count=int(plen / 4))
        b = numpy.bitwise_xor(data, mask).tostring()

    if plen % 4:
        dtype = numpy.dtype('B')
        if sys.byteorder == 'big':
            dtype = dtype.newbyteorder('>')

        mask = numpy.fromstring(mask_str, dtype, count=(plen % 4))
        data = numpy.frombuffer(buf, dtype,
                                offset=plen - (plen % 4), count=(plen % 4))
        c = numpy.bitwise_xor(data, mask).tostring()

    return b + c


def time_array(data):
    a = array.array('B')
    a.fromstring(data)

    for i in range(len(data)):
        a[i] ^= mask[i % 4]

    return a.tostring()


def time_bytearray(data):
    a = bytearray(data)

    for i in range(len(a)):
        a[i] ^= mask[i % 4]

    return a.decode('latin-1')


def wrapper(func, *args, **kwargs):
    def wrapped():
        return func(*args, **kwargs)

    return wrapped


if __name__ == '__main__':
    with open('/dev/urandom', 'r') as f:
        data = f.read(4096 * 16)

    for func in (time_array, time_bytearray, time_numpy):
        print timeit.timeit(wrapper(func, data), number=1000)


# Results: 
# 13.1004390717
# 11.6302118301
# 0.0161831378937