東京Ruby会議の資料

1. mruby/c
Kazuaki Tanaka
Kyushu Institute of Technology

2. 自己紹介
• 九州工業大学 Kyutech, Fukuoka
• Lectures
– Programming
– Algorithms and data structures
– Database
– Robot sensor processing

3. Joint research project
• Digital signage devices

4. mruby
軽量Ruby
• Ruby for embedded systems
– Small, Lightweight
– Portable
– Configurable
• METI project work

5. mruby
Lightweight
• < 400KB
• One chip microprocessor
ARM Coretex-M4 168MHz
1MB SRAM, 1MB Flash
enzi mruby board,
http://enzi.cc/

6. mruby
Portable
• Executing mruby bytecode using mruby VM
Source
Code
program.rb
Byte
Code
program.mrb
mrbc
Device A
Execute
mruby VM
Device B
Execute
mruby VM
PC
Execute
mruby VM

7. mruby
Configurable
• mrbgems
– VM configuration
• Add one line in build_config.rb
conf.gem :github => 'iij/mruby-socket’
http://mruby.org/libraries/

8. mruby/c project
• mruby for more smaller device
• Concurrent mruby execution without OS
• “/c” stands for compact and concurrent
ARM Coretex-M3 80MHz
64KB SRAM, 256KB Flash
PSoC5LP,
http://cypress.com/

9. Demo
mruby/c
PSoC5LP
ARM Coretex-M3 80MHz
64KB SRAM, 256KB Flash

10. Details
mruby/c
• GC
• Concurrency
• Boot

11. GC
mruby/c
No GC

12. How it works?
• Small mruby/c program only supported
• When a program ended, memory initialized
• How to support long term execution?
– Use concurrency

13. Concurrency
mruby/c
• mruby/c is for Non-OS environment
• But expect multiple programs execution
VM dispatches
mruby programs

14. Concurrency
mruby/c
OP_LOAD
OP_ADDI
OP_JMP
・
・
OP_LOADI
OP_SEND
OP_LOAD
・
・
mruby VM
One Instruction
One Instruction
Execute
Program A
Program B
Reg.
Stack
Program A
work
Reg.
Stack
Program B
work
Symbol
Class
Method
Global
Shared

15. Demo
mruby/c, concurrency
i = 100
while i<200 do
puts i
i = i + 1
end
i = 1000
while i<1100 do
puts i
i = i + 1
end

16. Demo
mruby/c, concurrency
$lock = true
i = 1
while i<10 do
puts i
i = i + 1
end
$lock = false
while $lock do
end
i = 100
while i<110 do
puts i
i = i + 1
end
Using spinlock without mutual exclusion >_<

17. Boot
• Boot process =
+ Initialize VM work
+ Create classes
+ Register all the methods to classes
1. Create entry point to a method
2. Get symbol of a method
3. Add a element to hash table
for all methods

18. Boot
mruby/c
• Simple Registration, using linked list.
[s]
Loop count

19. GET mruby and mruby/c
• mruby
• mruby/c
https://github.com/mrubyc/mrubyc
https://github.com/mruby/mruby
http://forum.mruby.org/
http://www.s-itoc.jp/activity/research/mruby/

21. 良いことづくめ？
• mruby/cは，多くの制約があります
– クラス，メソッド不足
– Fixnum だけ，だからあふれます
– Arrayは線形リスト，だから…
– メソッドは線形リストで管理，だから…
– メモリは静的に確保します
まだまだ開発途上です
ご協力ください！