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# the decoder works off a reader
# the encoder returns bytearray
def hex2bytes(h):
return bytearray(h.decode('hex'))
def bytes2hex(b):
if type(b) in (str, str):
return "".join([hex(ord(c))[2:].zfill(2) for c in b])
else:
return bytes2hex(b.decode())
# expects uvarint64 (no crazy big nums!)
def uvarint_size(i):
if i == 0:
return 0
for j in range(1, 8):
if i < 1 << j * 8:
return j
return 8
# expects i < 2**size
def encode_big_endian(i, size):
if size == 0:
return bytearray()
return encode_big_endian(i // 256, size - 1) + bytearray([i % 256])
def decode_big_endian(reader, size):
if size == 0:
return 0
firstByte = reader.read(1)[0]
return firstByte * (256 ** (size - 1)) + decode_big_endian(reader, size - 1)
# ints are max 16 bytes long
def encode_varint(i):
negate = False
if i < 0:
negate = True
i = -i
size = uvarint_size(i)
if size == 0:
return bytearray([0])
big_end = encode_big_endian(i, size)
if negate:
size += 0xF0
return bytearray([size]) + big_end
# returns the int and whats left of the byte array
def decode_varint(reader):
size = reader.read(1)[0]
if size == 0:
return 0
negate = True if size > int(0xF0) else False
if negate:
size = size - 0xF0
i = decode_big_endian(reader, size)
if negate:
i = i * (-1)
return i
def encode_string(s):
size = encode_varint(len(s))
return size + bytearray(s, 'utf8')
def decode_string(reader):
length = decode_varint(reader)
raw_data = reader.read(length)
return raw_data.decode()
def encode_list(s):
b = bytearray()
list(map(b.extend, list(map(encode, s))))
return encode_varint(len(s)) + b
def encode(s):
print('encoding', repr(s))
if s is None:
return bytearray()
if isinstance(s, int):
return encode_varint(s)
elif isinstance(s, str):
return encode_string(s)
elif isinstance(s, list):
return encode_list(s)
elif isinstance(s, bytearray):
return encode_string(s)
else:
print("UNSUPPORTED TYPE!", type(s), s)
if __name__ == '__main__':
ns = [100, 100, 1000, 256]
ss = [2, 5, 5, 2]
bs = list(map(encode_big_endian, ns, ss))
ds = list(map(decode_big_endian, bs, ss))
print(ns)
print([i[0] for i in ds])
ss = ["abc", "hi there jim", "ok now what"]
e = list(map(encode_string, ss))
d = list(map(decode_string, e))
print(ss)
print([i[0] for i in d])