Coverage for nuts.utils : 89%

import os 

import quopri 

import six 

import quopri 

def ascii_bin(binstr): 

    return repr(quopri.encodestring(binstr)) 

def encode_version(version): 

    """ Takes a version like '1.0' or '2.1' and encodes it into a single byte. """ 

    major, minor = map(int, version.split(b'.')) 

    if not (0 < major < 16 and 0 <= minor < 16): 

        raise ValueError("Can't encode version %s, major or minor version outside range(0, 16)" % version) 

    return six.int2byte(major << 4 | minor) 

def decode_version(version): 

    """ Takes a byte version and decodes it into human-readable <major>.<minor> format. """ 

    if len(version) != 1: 

        raise ValueError("Can only decode a single byte!") 

    major = six.byte2int(version) >> 4 

    minor = six.byte2int(version) & 15 

    return ('%d.%d' % (major, minor)).encode('ascii') 

def rng(num_bytes): 

    """ Read `num_bytes` from the RNG. """ 

31    if os.path.exists('/dev/hwrng'): 

        with open('/dev/hwrng', 'r') as hwrng: 

            return hwrng.read(num_bytes) 

    else: 

        return os.urandom(8) 

def encode_varint(i): 

    """ Encode a positiv integer to a variable length byte string. """ 

40    if i < 0: 

        raise ArgumentError('Cannot encode negative numbers as varint!') 

    res = [six.int2byte(i % 128)] 

    while i > 127: 

        i >>= 7 

        res.append(six.int2byte((i % 128) | 128)) 

    return b''.join(reversed(res)) 

def decode_varint(s): 

    """ Decode a variable length byte string into a positive integer. 

    Note that input must be an array of ints (the way python 3 iterates over a byte string). 

    """ 

    res = 0 

    for exp, c in enumerate(reversed(s)): 

        res += (c & 127)<<(exp*7) 

    return res