"""
Consistent Overhead Byte Stuffing (COBS)

This version is for Python 3.x.

----------------------------------------------------------------------------
Copyright (c) 2010 Craig McQueen

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
----------------------------------------------------------------------------

https://bitbucket.org/cmcqueen1975/cobs-python/wiki/Home
"""


class DecodeError(Exception):
    pass


def _get_buffer_view(in_bytes):
    mv = memoryview(in_bytes)
    if mv.ndim > 1 or mv.itemsize > 1:
        raise BufferError('object must be a single-dimension buffer of bytes.')
    return mv

def encode(in_bytes):
    """Encode a string using Consistent Overhead Byte Stuffing (COBS).

    Input is any byte string. Output is also a byte string.

    Encoding guarantees no zero bytes in the output. The output
    string will be expanded slightly, by a predictable amount.

    An empty string is encoded to '\\x01'"""
    if isinstance(in_bytes, str):
        raise TypeError('Unicode-objects must be encoded as bytes first')
    in_bytes_mv = _get_buffer_view(in_bytes)
    final_zero = True
    out_bytes = bytearray()
    idx = 0
    search_start_idx = 0
    for in_char in in_bytes_mv:
        if in_char == b'\x00':
            final_zero = True
            out_bytes.append(idx - search_start_idx + 1)
            out_bytes += in_bytes_mv[search_start_idx:idx]
            search_start_idx = idx + 1
        else:
            if idx - search_start_idx == 0xFD:
                final_zero = False
                out_bytes.append(0xFF)
                out_bytes += in_bytes_mv[search_start_idx:idx+1]
                search_start_idx = idx + 1
        idx += 1
    if idx != search_start_idx or final_zero:
        out_bytes.append(idx - search_start_idx + 1)
        out_bytes += in_bytes_mv[search_start_idx:idx]
    return bytes(out_bytes)


def decode(in_bytes):
    """Decode a string using Consistent Overhead Byte Stuffing (COBS).

    Input should be a byte string that has been COBS encoded. Output
    is also a byte string.

    A cobs.DecodeError exception will be raised if the encoded data
    is invalid."""
    if isinstance(in_bytes, str):
        raise TypeError('Unicode-objects are not supported; byte buffer objects only')
    in_bytes_mv = _get_buffer_view(in_bytes)
    out_bytes = bytearray()
    idx = 0

    if len(in_bytes_mv) > 0:
        while True:
            length = ord(in_bytes_mv[idx])
            if length == 0:
                raise DecodeError("zero byte found in input")
            idx += 1
            end = idx + length - 1
            copy_mv = in_bytes_mv[idx:end]
            if b'\x00' in copy_mv:
                raise DecodeError("zero byte found in input")
            out_bytes += copy_mv
            idx = end
            if idx > len(in_bytes_mv):
                raise DecodeError("not enough input bytes for length code")
            if idx < len(in_bytes_mv):
                if length < 0xFF:
                    out_bytes.append(0)
            else:
                break
    return bytes(out_bytes)

Add Python COBS encode and decode functions