def _int2bytes(number, block_size=None):
r"""Converts a number to a string of bytes.
Usage::
>>> _int2bytes(123456789)
'\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789))
123456789
>>> _int2bytes(123456789, 6)
'\x00\x00\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789, 128))
123456789
>>> _int2bytes(123456789, 3)
Traceback (most recent call last):
...
OverflowError: Needed 4 bytes for number, but block size is 3
@param number: the number to convert
@param block_size: the number of bytes to output. If the number encoded to
bytes is less than this, the block will be zero-padded. When not given,
the returned block is not padded.
@throws OverflowError when block_size is given and the number takes up more
bytes than fit into the block.
"""
# Type checking
if not is_integer(number):
raise TypeError("You must pass an integer for 'number', not %s" % number.__class__)
if number < 0:
raise ValueError("Negative numbers cannot be used: %i" % number)
# Do some bounds checking
if number == 0:
needed_bytes = 1
raw_bytes = [ZERO_BYTE]
else:
needed_bytes = common.byte_size(number)
raw_bytes = []
# You cannot compare None > 0 in Python 3x. It will fail with a TypeError.
if block_size and block_size > 0:
if needed_bytes > block_size:
raise OverflowError("Needed %i bytes for number, but block size " "is %i" % (needed_bytes, block_size))
# Convert the number to bytes.
while number > 0:
raw_bytes.insert(0, byte(number & 0xFF))
number >>= 8
# Pad with zeroes to fill the block
if block_size and block_size > 0:
padding = (block_size - needed_bytes) * ZERO_BYTE
else:
padding = EMPTY_BYTE
return padding + EMPTY_BYTE.join(raw_bytes)
def _int2bytes(number, block_size=None):
if not is_integer(number):
raise TypeError("You must pass an integer for 'number', not %s" %
number.__class__)
if number < 0:
raise ValueError('Negative numbers cannot be used: %i' % number)
if number == 0:
needed_bytes = 1
raw_bytes = [ZERO_BYTE]
else:
needed_bytes = common.byte_size(number)
raw_bytes = []
if block_size and block_size > 0:
if needed_bytes > block_size:
raise OverflowError(
'Needed %i bytes for number, but block size is %i' %
(needed_bytes, block_size))
while number > 0:
raw_bytes.insert(0, byte(number & 255))
number >>= 8
if block_size and block_size > 0:
padding = (block_size - needed_bytes) * ZERO_BYTE
else:
padding = EMPTY_BYTE
return padding + EMPTY_BYTE.join(raw_bytes)
def _int2bytes(number, block_size=None):
r"""Converts a number to a string of bytes.
Usage::
>>> _int2bytes(123456789)
b'\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789))
123456789
>>> _int2bytes(123456789, 6)
b'\x00\x00\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789, 128))
123456789
>>> _int2bytes(123456789, 3)
Traceback (most recent call last):
...
OverflowError: Needed 4 bytes for number, but block size is 3
@param number: the number to convert
@param block_size: the number of bytes to output. If the number encoded to
bytes is less than this, the block will be zero-padded. When not given,
the returned block is not padded.
@throws OverflowError when block_size is given and the number takes up more
bytes than fit into the block.
"""
# Type checking
if not is_integer(number):
raise TypeError("You must pass an integer for 'number', not %s" %
number.__class__)
if number < 0:
raise ValueError('Negative numbers cannot be used: %i' % number)
# Do some bounds checking
if number == 0:
needed_bytes = 1
raw_bytes = [b'\x00']
else:
needed_bytes = common.byte_size(number)
raw_bytes = []
# You cannot compare None > 0 in Python 3x. It will fail with a TypeError.
if block_size and block_size > 0:
if needed_bytes > block_size:
raise OverflowError('Needed %i bytes for number, but block size '
'is %i' % (needed_bytes, block_size))
# Convert the number to bytes.
while number > 0:
raw_bytes.insert(0, byte(number & 0xFF))
number >>= 8
# Pad with zeroes to fill the block
if block_size and block_size > 0:
padding = (block_size - needed_bytes) * b'\x00'
else:
padding = b''
return padding + b''.join(raw_bytes)
def _int2bytes(number, block_size=None):
r"""Converts a number to a string of bytes.
Usage::
>>> _int2bytes(123456789)
'\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789))
123456789
>>> _int2bytes(123456789, 6)
'\x00\x00\x07[\xcd\x15'
>>> bytes2int(_int2bytes(123456789, 128))
123456789
>>> _int2bytes(123456789, 3)
Traceback (most recent call last):
...
OverflowError: Needed 4 bytes for number, but block size is 3
@param number: the number to convert
@param block_size: the number of bytes to output. If the number encoded to
bytes is less than this, the block will be zero-padded. When not given,
the returned block is not padded.
@throws OverflowError when block_size is given and the number takes up more
bytes than fit into the block.
"""
if not is_integer(number):
raise TypeError("You must pass an integer for 'number', not %s" %
number.__class__)
if number < 0:
raise ValueError('Negative numbers cannot be used: %i' % number)
if number == 0:
needed_bytes = 1
raw_bytes = [ZERO_BYTE]
else:
needed_bytes = common.byte_size(number)
raw_bytes = []
if block_size and block_size > 0:
if needed_bytes > block_size:
raise OverflowError(
'Needed %i bytes for number, but block size is %i' %
(needed_bytes, block_size))
while number > 0:
raw_bytes.insert(0, byte(number & 255))
number >>= 8
if block_size and block_size > 0:
padding = (block_size - needed_bytes) * ZERO_BYTE
else:
padding = EMPTY_BYTE
return padding + EMPTY_BYTE.join(raw_bytes)
def bit_size(num):
"""
Number of bits needed to represent a integer excluding any prefix
0 bits.
Usage::
>>> bit_size(1023)
10
>>> bit_size(1024)
11
>>> bit_size(1025)
11
:param num:
Integer value. If num is 0, returns 0. Only the absolute value of the
number is considered. Therefore, signed integers will be abs(num)
before the number's bit length is determined.
:returns:
Returns the number of bits in the integer.
"""
if num == 0:
return 0
if num < 0:
num = abs(num)
if not is_integer(num):
raise TypeError('not integer')
try:
return bit_length(num)
except AttributeError:
raise TypeError('bit_size(num) only supports integers, not %r' %
type(num))
def assert_int(var, name):
if is_integer(var):
return
raise TypeError('%s should be an integer, not %s' % (name, var.__class__))
def assert_int(var, name):
if is_integer(var):
return
raise TypeError('%s should be an integer, not %s' % (name, var.__class__))