How to run Objective-C on Bare-metal ARM

1. Embedded Objective-C
Shotaro “Fantom” Uchida

2. Who am I?
• I am Java Enthusiast so far...
– USB EHCI stack in Java
– TCP/IP in Java
– IEEE802.11 in Java
– ZigBee in Java
– OAuth 2.0 in Java
– XModem in Java
• I do everything (Hardware/Software) for Java
• 仕事下さい。よろしくお願いします。
But today...

3. Objective-C
#import "XYZPerson.h"
@implementation XYZPerson
- (void)sayHello {
NSLog(@"Hello, World!");
}
@end

4. Arduino

5. #import "XYZPerson.h"
@implementation XYZPerson
- (void)sayHello {
NSLog(@"Hello, World!");
}
@end
If I could...

6. Existing Solutions
Language
Bare-Metal C
Arduino Java-like
mbed C++
JavaME JavaME
Tessel JavaScript
Why not Objective-C ???

7. Is ObjC Proprietary?

8. How different?
Java
Java
C++ Runtime
JVM
C++
C Runtime
C
ObjC Runtime
Smalltalk-like
C++ Objective-C

9. 5 Reasons Why Objective-C is the
Best
• C++ sucks.
• You can use “Pure C” anytime anywhere.
• It also means that you can use assembly
anytime.
• Powerful object-oriented language, but still
faster than Java.
• And C++ sucks.

10. Disadvantages
• Large memory footprint
– Classes are loaded at init array calls.
– No “class-loader” system.
– Needs to manage all method symbols i.e.
selectors.
• Message lookup

11. “Big 3” ObjC Runtime
Compiler Modern-ObjC Cons
Apple Clang Yes iOS/OSX only
libobjc GCC, Clang No Out-dated
No “Foundation”
GNUStep GCC, Clang Yes (w/ Clang) Out-dated
Huge

12. Another newer runtime “ObjFW”
• Lightweight
– < 1MB
• Portable
– Multi-platform includes Apple devices
– Works with PSP, Wii, and NintendoDS !
• Modern-ObjC
• Clang supported
– -fobjc-runtime=objfw
– Don't stop the support of ObjFW!! Plz!!
• Github
– https://github.com/Midar/objfw

13. Requirements to run ObjFW
• Still, you need 1MB+ RAM
– External RAM, typically
– Bootloader
• 1MB+ Flash
• “Fast enough” processor

14. Silabs EFM32 Wonder Gecko
• Cortex-M4F@48MHz
• External Bus Interface
– Up to 4x256MB
– Support code execution via I/D bus
• Ultra low power
• SDK with big memory!
– 4MB PSRAM
– 16MB Nor Flash

15. It works!!
• Ubuntu 14.04
• Eclipse Kepler
– With debugging!!
• Clang/LLVM 3.5 (trunk)
– Some nice major updates for ARM ;)
• ObjFW 0.8-dev
• Need some workaround...
– Read my blog: http://xmaker.mx/archives/14

18. What's Next?
• Threading support
– CMSIS-RTOS (RTX)
– Free RTOS
• Socket support
– lwIP
• File support
• Hardware APIs

19. ObjC
Powered
ObjArduino
Relese Date: When It's Done