A few years ago I created a bare metal demo on an ARM Cortex-M4 microcontroller entirely in D.  It was just a demonstration that one could do bare metal programming for microcontrollers in D without any dependencies on C or assembly.  It was also a proof of some ideas I had about leveraging compile-time features of D to generate highly-optimized code (both small and fast) for these resource constrained systems.  I hit a wall, however, with Issue 14758[0], and ultimately abandoned D for other alternatives.

Well, that issue was recently fixed in GDC [1].  In addition, he GDC developers did some work to reduce the number of phony stubs one had to add to the runtime to get a build [2], removed the "shared is volatile" hack, and implemented the `volatileLoad/Store` intrinsics so I no longer need to do volatile access in assembly.  So, I decided to give it another try, and updated that demo. You can see the results at https://github.com/JinShil/stm32f42_discovery_demo

A few observations:
* It is a better experience than it was a few years ago.  Fewer dirty hacks are required, and the resulting binary is small and fast.
* Everything is in D (inline assembly is D).  There's no need for any C or assembly startup code, and no need for silly things like -betterC (i.e. -worseD).  If you don't want the overhead from a feature of D, don't use it.
* Compile times are quite slow (about 1 minute to get a 3kB binary).  Some discussion about that is taking place on the GDC forum [4].
* -O2 and -O3 give me a broken binary, but -O0, -O1, and -Os work well.

I'm not sure where I'll go from here.  I'm interested in helping an amputee play the drums again, and building my own mechanical keyboard, so I probably won't be spending much more time on this LCD demo, except maybe to help compiler devs debug some issues.  However, I might spend some more time with D in the near future, and see how far I can take this.  I'm still not as excited as I once was, but it's nice to see these improvements.

Anyway, Well done, GDC!

Mike

[0] - TypeInfo causes excessive binary bloat - https://issues.dlang.org/show_bug.cgi?id=14758
[1] - Put the TypeInfo name field into a static var - https://github.com/D-Programming-GDC/GDC/pull/505
[2] - Refactor and reformat typeinfo.cc - https://github.com/D-Programming-GDC/GDC/pull/456
[3] - Slow compile-time discussion at GDC forum - http://forum.dlang.org/post/iqryqssxooypdnszmzmg@forum.dlang.org

Thanks for your work with bare metal MCUs! I am dreaming that someday I can program smart house IoT automation on D.

On Thursday, 20 July 2017 at 17:09:40 UTC, Mr.D wrote:
> Thanks for your work with bare metal MCUs! I am dreaming that someday I can program smart house IoT automation on D.

You already can; it just may not be the most professional experience.  If you have the hardware and the time, do it!

Mike

On Friday, 21 July 2017 at 00:27:09 UTC, Mike wrote:
> On Thursday, 20 July 2017 at 17:09:40 UTC, Mr.D wrote:
>> Thanks for your work with bare metal MCUs! I am dreaming that someday I can program smart house IoT automation on D.
>
> You already can; it just may not be the most professional experience.  If you have the hardware and the time, do it!
>
> Mike

Thanks for your work!!!!

On Thursday, 20 July 2017 at 12:23:31 UTC, Mike wrote:
> A few years ago I created a bare metal demo on an ARM Cortex-M4 microcontroller entirely in D.  It was just a demonstration that one could do bare metal programming for microcontrollers in D without any dependencies on C or assembly.  It was also a proof of some ideas I had about leveraging compile-time features of D to generate highly-optimized code (both small and fast) for these resource constrained systems.  I hit a wall, however, with Issue 14758[0], and ultimately abandoned D for other alternatives.

It has a lot of potential. I always hope that someone will start a 3d Printer firmware written in D for a 32bit microcontroller.

On Friday, 21 July 2017 at 00:27:09 UTC, Mike wrote:
> On Thursday, 20 July 2017 at 17:09:40 UTC, Mr.D wrote:
>> Thanks for your work with bare metal MCUs! I am dreaming that someday I can program smart house IoT automation on D.
>
> You already can; it just may not be the most professional experience.  If you have the hardware and the time, do it!
>
> Mike

I am stopped by the lack of a system library for work with GPIO, PWM etc specific MCU things.

On Friday, 21 July 2017 at 07:40:20 UTC, Andrea Fontana wrote:
> On Thursday, 20 July 2017 at 12:23:31 UTC, Mike wrote:
>> A few years ago I created a bare metal demo on an ARM Cortex-M4 microcontroller entirely in D.  It was just a demonstration that one could do bare metal programming for microcontrollers in D without any dependencies on C or assembly.  It was also a proof of some ideas I had about leveraging compile-time features of D to generate highly-optimized code (both small and fast) for these resource constrained systems.  I hit a wall, however, with Issue 14758[0], and ultimately abandoned D for other alternatives.
>
> It has a lot of potential. I always hope that someone will start a 3d Printer firmware written in D for a 32bit microcontroller.

Can't wait to see that day

On Thursday, 20 July 2017 at 12:23:31 UTC, Mike wrote:

> * -O2 and -O3 give me a broken binary, but -O0, -O1, and -Os work well.

Turned out to be a problem in my code, not with the compiler.  All optimiziation options work well.

Mike

Am 21.07.2017 um 09:40 schrieb Andrea Fontana:
> It has a lot of potential. I always hope that someone will start a 3d
> Printer firmware written in D for a 32bit microcontroller.

I've actually started to implement a GCode processor in D a while ago, because I was unsatisfied with the open source firmwares that exist. It's more tailored towards CNC routers, but since those are pretty similar that shouldn't be a big problem. The bad news is that I don't have time to work on it anymore and it was still at a relatively early stage.

On Thursday, 20 July 2017 at 12:23:31 UTC, Mike wrote:
> A few years ago I created a bare metal demo on an ARM Cortex-M4 microcontroller entirely in D.  It was just a demonstration that one could do bare metal programming for microcontrollers in D without any dependencies on C or assembly.  It was also a proof of some ideas I had about leveraging compile-time features of D to generate highly-optimized code (both small and fast) for these resource constrained systems.  I hit a wall, however, with Issue 14758[0], and ultimately abandoned D for other alternatives.
>
> Well, that issue was recently fixed in GDC [1].  In addition, he GDC developers did some work to reduce the number of phony stubs one had to add to the runtime to get a build [2], removed the "shared is volatile" hack, and implemented the `volatileLoad/Store` intrinsics so I no longer need to do volatile access in assembly.  So, I decided to give it another try, and updated that demo. You can see the results at https://github.com/JinShil/stm32f42_discovery_demo

Congratulations, Mike.

https://www.reddit.com/r/programming/comments/6pn31c/d_on_bare_metal_stm32f4_redux/

Could someone post to Hacker News?  I don't have enough rep for it to propagate.