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