binmark is a markup language and tool for describing binary files, that is easier to read and write than a continuous stream of hexadecimal characters.

This implementation is a C/C++ library and command line tool.

The following characters are supported:

Given the following sample input file, which is reasonably easy read:

30             # Packet Type 3: Publish
.17            # Remaining length (17 bytes)
0004           # Topic name length
"test"         # Topic name
"hello world"  # Payload

The default is to output as a binary stream - visualised here using the hexdump command:

./binmark -b tests/mqtt_publish.bm | hexdump -C
00000000  30 11 00 04 74 65 73 74  68 65 6c 6c 6f 20 77 6f  |0...testhello wo|
00000010  72 6c 64                                          |rld|
00000013

It is also possible to output as C data structure:

./binmark -c tests/mqtt_publish.bm
uint8_t buffer[] = {
    0x30, 0x11, 0x00, 0x04, 0x74, 0x65, 0x73, 0x74, 
    0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x77, 0x6f, 
    0x72, 0x6c, 0x64
};

Or as a stream of hexadecimal text:

./binmark -x tests/mqtt_publish.bm
301100047465737468656c6c6f20776f726c64

I created binmark after my test cases, when writing test cases for my Arduino IPv6 Library, EtherSia, started resulting in long strings of hexadecimal characters in my code. I decided that these would be better in seperate external files and realised that I had the freedom to decide on the file format, to make them easier to read and write.

A long stream of hexadecimal is difficult to both read and write - particularly picking out the different fields and sections. By adding some whitespace, punctuation and comments, it is much easier.

Possible uses:

• Describing expected data for automated tests
• Creating new file formats before tools to generate them exist
• Documenting a data structure in a human readable way
• Alternative to a using a hex editor

This was my thought process while designing binmark:

• Readable and concise to write for humans
• Simple for a machine to parse and convert
• Streamable - don't require input to be loaded into a buffer more parsing
• ASCII input - try and avoid potential weird character-set problems
• Not so complex that there wouldn't be other implementations in other languages

• JavaScript: https://github.com/njh/binmark-js

binmark is licensed under the terms of the MIT license. See the file LICENSE for details.

binmark was originally written in 2016 with the name hext. It was renamed in 2023 to have a more unique name that wasn't being used by other projects.

• Author: Nicholas J Humfrey
• Twitter: @njh