This presentation will discover how Ruby can be launched even on MCUs. It covers implementation of Ruby virtual machine, a timeline of porting experiences and some shiny demo with blinking LEDs - now in Ruby. Author - Mikhail Bortnyk, a senior developer, who has spoken with this presentation at RubyMeditation #9.

1. LAUNCHING RUBY IN 32
KILOBYTES
MIKHAIL BORTNYK

2. LAUNCHING RUBY IN 32 KILOBYTES
WHO AM I
▸ Mikhail Bortnyk, (not only) Ruby developer
▸ kottans.org co-founder
▸ github: @vessi
▸ twitter: @mikhailbortnyk

3. LAUNCHING RUBY IN 32 KILOBYTES
FOR WHY?
▸ because I can
▸ I love Ruby
▸ interested in IoT
▸ learn more about languages virtual machines
▸ learn more about optimisation
▸ get a touch with a real hardware
▸ I want to get fucking led blinking!

4. LAUNCHING RUBY IN 32 KILOBYTES
OPTIONS I KNEW BEFORE
▸ Ruby
▸ mRuby

5. LAUNCHING RUBY IN 32 KILOBYTES
RUBY
▸ Pros:
▸ full language stack
▸ very long story
▸ most of bugs cleared
▸ I have everyday work experience
▸ Cons:
▸ consumes too much memory (valgrind shows ~9Mb)
▸ too big
▸ platform-dependent
▸ bytecode is very experimental

6. LAUNCHING RUBY IN 32 KILOBYTES
MRUBY
▸ Pros:
▸ relatively smaller
▸ actively supported by @matz
▸ proved builds on bigger MCUs (Raspberry Pi and powerful ChipKIT boards)
▸ code can be compiled into byte code to reduce execution time
▸ Cons:
▸ still consumes too much memory (but only 4% from big Ruby, ~400kb)
▸ has complicated build system
▸ partially connected with filesystem so you can’t use FS-less configurations

7. LAUNCHING RUBY IN 32 KILOBYTES
LIMITATIONS
▸ Result build should:
▸ fit in 32K of RAM
▸ take less than 512K
▸ can operate without file system
▸ It will be good if result build can operate with target’s
hardware

8. LAUNCHING RUBY IN 32 KILOBYTES
FIRST TRY
▸ Author: Doug Bradbury
▸ Date: 19 Dec 2008
▸ Target board: Glomation GESBC-2440
▸ Target params: 400MHz ARM CPU, 128 MB SDRAM, 64
MB FLASH and Linux 2.6.18
▸ Ruby version: 1.8.6-p111

9. LAUNCHING RUBY IN 32 KILOBYTES
NEXT STEP (POSSIBLY NOT VERY ACCURATE)
▸ Author: kyab
▸ Date: 31 Dec 2012
▸ Target board: ChipKIT Max32
▸ Target params: PIC32MX795F512L 80MHz MCU, 128KB RAM, 512KB flash
▸ mRuby version: 1.0.0
▸ Caveats: lost Regexps, reduced heap 16 times (64 objects instead of 1024),
lost Time class, gems are disabled
▸ No REPL, only constant code evaluation
▸ requires MPIDE to cross-compile

10. AND I HAVE
FOUND
LAUNCHING RUBY IN 32 KILOBYTES

11. LAUNCHING RUBY IN 32 KILOBYTES
MRUBY/C PROTOTYPE
▸ Author: Shimane IT Open-Innovation Centre (in reality the
only developer is Kazuaki Tanaka)
▸ First presentation of idea: 11 Nov 2015, on slideshare
▸ I found this presentation and wrote email to achieve very
alpha version: 4 Mar 2016
▸ Project gone opensource: 17 Mar 2016

12. LAUNCHING RUBY IN 32 KILOBYTES
MRUBY/C DESCRIPTION
▸ Written in pure C, Makefiles are used to build
▸ Fits in 16K of memory
▸ Totally lost everything in stdlib, only Array, Float and Object
classes left
▸ More than 40% of VM instructions are not implemented yet
▸ Heap is statically linked (length is configurable in time of
compilation)

13. DEMO TIME
I AM GOING TO COMPILE RUBY AND BYTECODE,
FLASH BOARDS, BLINK LEDS AND LOOK PROUD
FOR NO REASON
LAUNCHING RUBY IN 32 KILOBYTES

14. LAUNCHING RUBY IN 32 KILOBYTES
WHAT HAVE I DID
▸ Added cross-compiling system (stolen idea from
micropython)
▸ Added simple HAL to avoid printf calls and remove libc
dependency (-10kb of flash size)
▸ Fixed lambda support (not totally)
▸ Added constants support

15. LAUNCHING RUBY IN 32 KILOBYTES
WHAT I AM PLANNING TO DO
▸ Add IREP subsequences support (IREP is byte code
sequence)
▸ Add runtime class declaration
▸ Move to dynamic memory management system
▸ Try to port lexer and compiler parts
▸ Try to implement REPL
▸ Try to implement network access (need ESP8266 board!)

16. LAUNCHING RUBY IN 32 KILOBYTES
THANKS SECTION
▸ To Mykhailo Odyniuk: this work would be totally
impossible without him. He provided me two
development boards I used in time of porting
▸ To Shimane ITOC and Kenji Sugihara personally for quick
replies and good presentation
▸ To Kazuaki Tanaka for the great work he did implementing
alpha and beta versions of mruby/c

17. LAUNCHING RUBY IN 32 KILOBYTES
KAZUAKI TANAKA
▸ The guy to say ‘Arigato!’
▸ @kaz0505 on Github
▸ Associate professor at Kyushu
Institute of Technology
▸ Profile on LinkedIn

18. QUESTIONS
AND ANSWERS
LAUNCHING RUBY IN 32 KILOBYTES