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Current Path : /lib/python3.6/site-packages/pyasn1/compat/ |
Current File : //lib/python3.6/site-packages/pyasn1/compat/integer.py |
# # This file is part of pyasn1 software. # # Copyright (c) 2005-2017, Ilya Etingof <etingof@gmail.com> # License: http://pyasn1.sf.net/license.html # import sys try: import platform implementation = platform.python_implementation() except (ImportError, AttributeError): implementation = 'CPython' from pyasn1.compat.octets import oct2int, null, ensureString if sys.version_info[0:2] < (3, 2) or implementation != 'CPython': from binascii import a2b_hex, b2a_hex if sys.version_info[0] > 2: long = int def from_bytes(octets, signed=False): if not octets: return 0 value = long(b2a_hex(ensureString(octets)), 16) if signed and oct2int(octets[0]) & 0x80: return value - (1 << len(octets) * 8) return value def to_bytes(value, signed=False, length=0): if value < 0: if signed: bits = bitLength(value) # two's complement form maxValue = 1 << bits valueToEncode = (value + maxValue) % maxValue else: raise OverflowError('can\'t convert negative int to unsigned') elif value == 0 and length == 0: return null else: bits = 0 valueToEncode = value hexValue = hex(valueToEncode)[2:] if hexValue.endswith('L'): hexValue = hexValue[:-1] if len(hexValue) & 1: hexValue = '0' + hexValue # padding may be needed for two's complement encoding if value != valueToEncode or length: hexLength = len(hexValue) * 4 padLength = max(length, bits) if padLength > hexLength: hexValue = '00' * ((padLength - hexLength - 1) // 8 + 1) + hexValue elif length and hexLength - length > 7: raise OverflowError('int too big to convert') firstOctet = int(hexValue[:2], 16) if signed: if firstOctet & 0x80: if value >= 0: hexValue = '00' + hexValue elif value < 0: hexValue = 'ff' + hexValue octets_value = a2b_hex(hexValue) return octets_value def bitLength(number): # bits in unsigned number hexValue = hex(abs(number)) bits = len(hexValue) - 2 if hexValue.endswith('L'): bits -= 1 if bits & 1: bits += 1 bits *= 4 # TODO: strip lhs zeros return bits else: def from_bytes(octets, signed=False): return int.from_bytes(bytes(octets), 'big', signed=signed) def to_bytes(value, signed=False, length=0): length = max(value.bit_length(), length) if signed and length % 8 == 0: length += 1 return value.to_bytes(length // 8 + (length % 8 and 1 or 0), 'big', signed=signed) def bitLength(number): return int(number).bit_length()