README.md

Rust implementation of golang challenge #1.

A simple binary file format for a drum machine is given. The task is to reverse it and implement a decoder for it.

Example output

With the challenge came some examples how the lost executable's outputs looked like. In fixtures/ are all the example binaries given. And in src/tests.rs are the respective example outputs.

Saved with HW Version: 0.808-alpha
Tempo: 120
(0) kick	|x---|x---|x---|x---|
(1) snare	|----|x---|----|x---|
(2) clap	|----|x-x-|----|----|
(3) hh-open	|--x-|--x-|x-x-|--x-|
(4) hh-close	|x---|x---|----|x--x|
(5) cowbell	|----|----|--x-|----|

File format

There is no real specification. But this is my understanding based on looking at the provided example files and reading the challenge description.

A file starts with a header and is followed by multiple lines. All numbers are encoded with big endianness.

Header

Size	encoding	Description
6	ASCII	magic bytes "SPLICE"
8	u64	file size (bytes after this field are counted)
32	ASCII	version string (of the editor used to create the file?)
4	f32	tempo

Line

Size	Encoding	Description
1	u8	id
4	u32	length of the name field (n_l)
n	ASCII	name
16	bool[]	data (byte-wise when to hit: 0 for no, 1 for yes)

To-do

• write example CLI that pretty prints the fixture's contents
• create documentation / tutorial / walk through
  • describe implementation steps
  • maybe add something (tests!?) that allows for better/easier debugging
    • find out how to properly debug