Simple encode/decode utilties for single-bit error correcting Hamming codes
Tested on Python >=3.6 and requires C++ compilers supporting C++17 features.
Install using pip as follows:
$ python -m pip install hamming-codecIf you wish to use the hamming-codec encoding/decoding from within C++,
one needs to include the single header file
src/cpp/hamming_codec.h in their project.
There are a few ways to do this:
- Copy the file hamming_codec.h into your project's include path.
- Add
hamming-codecas a sub-module (or equivalent) and use CMake to expose theHAMMING_CODEC_INCLUDE_DIRSvariable by callingadd_subdirectory(/path/to/hamming_codec)to your project's CMakeLists.txt file. See src/cpp/examples/CMakeLists.txt for an example.
Following either approach, you should be able to add #include "hamming_codec.h" to your
source code.
After following the Python installation, a commandline utility
hamming will be available to you, which can be used for simple encoding and decoding
of data words. Use hamming --help to show the full set of options and commands.
You can use the hamming commandline utility to encode messages of specified length
(in number of bits) as follows:
$ hamming encode 0x1234 16
0x2a3a1 21Which shows that the 16-bit message 0x1234 is encoded as a 21-bit word 0x2a3a1.
You can use the hamming commandline utility to decode messages of specified length (in number of bits) as follows:
$ hamming decode 0x2a3a1 21
0x1234 16Which shows that the 21-bit encoded message 0x2a3a1 is decoded back into the 16-bit word 0x1234.
Once you have installed hamming-codec, you can import the hamming_codec
module and perform encoding/decoding like so:
>>> import hamming_codec
>>> encoded_message = hamming_codec.encode(0x4235, 16)
>>> print(encoded_message)
010001010001110101100
>>> hex(int(encoded_message,2))
'0x8a3ac'
>>> decoded_message = hamming_codec.decode(int(encoded_message,2), len(encoded_message))
>>> print(decoded_message)
0100001000110101
>>> hex(int(decoded_message,2))
'0x4235'Following the steps to add hamming-codec to your include path,
you can encode/decode messages as follows:
#include "hamming_codec.h"
...
uint32_t n_bits = 16;
uint32_t input_message = 0x4235;
std::string encoded_message = hamming_codec::encode(input_message, n_bits);
std::cout << "Encoded message: 0x" << std::hex << std::stoul(encoded_message, 0, 2) << std::endl; // prints "Encoded message: 0x8a3ac"
std::string decoded_message = hamming_codec::decode(std::stoul(encoded_message, 0, 2), encoded_message.length());
std::cout << "Decoded message: 0x" << std::hex << std::stoul(decoded_message, 0, 2) << std::endl; // prints "Decoded message: 0x4235"After following the steps to build the C++ library, you can run the C++ examples. For example,
$ ./build/bin/example_encode 0x4235 16
0x8a3ac 21The Hamming encoding algorithm used within hamming-codec allows for single-bit error corrections. That
is, during the decoding process, errors in which a single bit has been flipped in the encoded message
can both be detected and corrected.
For example, if we flip a single bit
in the encoded message from a previous section such that the 21-bit word 0x2a3a1 becomes 0x2a1a1,
you will get the same decoded message as before:
$ hamming encode 0x1234 16
0x2a3a1 21
$ hamming decode 0x2a3a1 21
0x1234 16
$ hamming decode 0x2a1a1 21 # flipped a bit
0x1234 16 # ...but decodes the same as before!Further information about the Hamming encoding algorithm employed within hamming-codec can be found in the following resources: