def write_varint(outfile, value):
'''Writes a varint to a file.
@param outfile: the file-like object to write to. It should have a write()
method.
@returns the number of written bytes.
'''
# there is a big difference between 'write the value 0' (this case) and
# 'there is nothing left to write' (the false-case of the while loop)
if value == 0:
outfile.write(ZERO_BYTE)
return 1
written_bytes = 0
while value > 0:
to_write = value & 0x7f
value = value >> 7
if value > 0:
to_write |= 0x80
outfile.write(byte(to_write))
written_bytes += 1
return written_bytes
def write_varint(outfile, value):
'''Writes a varint to a file.
@param outfile: the file-like object to write to. It should have a write()
method.
@returns the number of written bytes.
'''
# there is a big difference between 'write the value 0' (this case) and
# 'there is nothing left to write' (the false-case of the while loop)
if value == 0:
outfile.write(ZERO_BYTE)
return 1
written_bytes = 0
while value > 0:
to_write = value & 0x7f
value = value >> 7
if value > 0:
to_write |= 0x80
outfile.write(byte(to_write))
written_bytes += 1
return written_bytes
def read_random_bits(nbits):
'''Reads 'nbits' random bits.
If nbits isn't a whole number of bytes, an extra byte will be appended with
only the lower bits set.
'''
nbytes, rbits = divmod(nbits, 8)
# Get the random bytes
randomdata = os.urandom(nbytes)
# Add the remaining random bits
if rbits > 0:
randomvalue = ord(os.urandom(1))
randomvalue >>= (8 - rbits)
randomdata = byte(randomvalue) + randomdata
return randomdata
def read_random_bits(nbits):
'''Reads 'nbits' random bits.
If nbits isn't a whole number of bytes, an extra byte will be appended with
only the lower bits set.
'''
nbytes, rbits = divmod(nbits, 8)
# Get the random bytes
randomdata = os.urandom(nbytes)
# Add the remaining random bits
if rbits > 0:
randomvalue = ord(os.urandom(1))
randomvalue >>= (8 - rbits)
randomdata = byte(randomvalue) + randomdata
return randomdata