embedded D?

[Chad J]

kenny wrote:
> quick background... I wanted to do some fast network socket stuff using libowfat... so I converted the h file and stuff... good stuff, then I remembered it was linked against dietlibc, not glibc. So, instead of converting to Tango (which is what I should have done), I added the necessary symbols to dietlibc for the GC to work, and converted phobos over.
> 
> I now have a bunch of code that I don't know what to do with... (I ended up converting/linking libowfat against glibc).
> 
> Would anyone be interested in an embedded D project? I would obviously maintain it and develop it, if there was interest. I have D phobos linked against dietlibc already. Once the gc is separate, I think I can get D producing 32K executables, dynamically linked against dietlibc + phobos or tango (leaning more toward tango).
> 
> At the moment, phobos + dietlibc only accounts for about 300KB extra, so it would actually be a very small installation (less than 1MB) compared to the monstrosity of glibc. dietlibc is a bit slower in a few functions though. One of the most often complaints I hear about D is it's executable size (because of statically linking phobos). Perhaps this can help
> 
> L3 phobos # dmd -gc -c test.d && gcc -static -nostdlib -L /usr/diet/lib-i386/ /usr/diet/lib-i386/start.o -o test test.o dmain2.o libphobos2.a -lpthread -D__dietlibc__ /usr/diet/lib-i386/libc.a -lgcc -lm -lowfat /usr/diet/lib-i386/libc.a
> L3 phobos # ldd test
>         not a dynamic executable
> L3 phobos # ls -l test
> -rwxr-xr-x 1 root root 390302 Aug 20 18:40 test
> L3 phobos # strip test
> L3 phobos # ls -l test
> -rwxr-xr-x 1 root root 279296 Aug 20 18:41 test
> 
> Ideas? Opinions? I know I wasted my time, but I want to make something useful out of it :) This would also allow D (assuming gdc support) to create small executables for ARM, alpha, sparc, s390, ppc, and mips.

No you didn't waste your time, you learned :)

Anyhow, while I do like the idea of small executable size, it is really 
not the thing stopping D from going embedded.  Yeah having a 300 kB exe 
would suck on a smartphone/pda, but it would still WORK and people tend 
to have 1-4 GB data cards jammed into such devices anyways.

It would be sweet to have small executable size though.  The demoscene 
might appreciate it.  It would also be NICE for smartphone type platforms.

I think what you are talking about is a D framework.  Have the GC and a 
whole load of library functions as a shared resource, outside of the 
executable.  Tango probably would be a prime candidate for such a thing. 
    Then executables merely consist of a bunch of some minimal code with 
calls to the framework, and maybe some runtime type info which is unique 
to the program and useful for the GC to avoid memory leaks.

<ramble>
Oh, I almost forgot to describe what IS stopping D from going on a 
smartphone.  So far I have managed to get gdc to target arm-wince-pe, 
basically an ARM processor with the WinCE OS.  Someone else managed to 
get gdc to target a Nokia device, which (correct me if I'm wrong) was a 
ARM processor with Symbian OS.

#1)  I'm the guy working on arm-wince-pe, and I'm not really working on 
it.  I'm a student with not enough time to do this kind of stuff, and I 
have other projects I'd rather work on.

#2)  While gdc on arm-wince-pe works for most of D, it is missing some 
important stuff like rectangular arrays and variadic functions.  Details 
are in the attachment "limitations.d".  This kind of stuff rests in the 
guts of GDC and GCC, and I have no idea how to fix these things.  I did 
try to debug and stacktrace, but all I ended up with was some very low 
level GCC code (probably in codegen) that I did not understand at all.

#3)  arm-wince-pe-gdc currently relies on newlib, thus incurring some 
licensing issues.  None of this would stop you from writing a commercial 
application in D on an ARM smartphone, but you'd have to pay attention 
to the licenses and give the appropriate credits/disclaimers/etc.  The 
less dedicated D programmers would probably not be pleased by this.

#4)  Haven't heard from the Nokia guys in a while.  I wonder if that 
option is ever going to become a default part of GDC.

There are other little issues with arm-wince-gdc, like the lack of 
Tango.  That simply needs some work to fix.  It isn't helped by the fact 
that GDC only builds gphobos by default.  I had plenty of pain trying to 
modify GDC's build scripts for gphobos to get it /just/ right, and I am 
not looking forward to repeating that with Tango, as much as I do love 
Tango.  Tango itself looks very portable.

For other reference, Manfred Hansen was nice enough to host the 
arm-wince-pe-gdc compiler on his website.  (Thank you Manfred)
http://www.steinmole.de/d/arm-wince-pe-gdc.tar.bz2
It includes binaries, source, and some documentation.

There was also some discussion on D.gnu from about a year ago involving 
the arm-wince-pe-gdc compiler.
</ramble>
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