nSDL 1.1.1 Anniversary Edition—The Ultimate TI-Nspire Graphics Library!

[Lionel Debroux]

You should switch to GCC 4.6.2, lkj: all "x.y.0" releases of GCC contain quite a few significant bugs
(though the last major disaster "x.y.0" release was GCC 4.0.0, i.e. years ago)

[lkj]

I never saw any bug, but I switched as you suggested.
I thought updating would be as complicated as setting up the ndless-SDK, but it was very easy

[hoffa]

Could somebody quickly check my code, it doesn't seem to print the value of f. Either I'm using nl_relocdata wrong, or then I'm too tired and am missing something silly.

http://pastebin.com/N2iiUhd1

That's more or less how SDL behaves at one point, and it's reallocating the function pointer that causes issues. The strings print out fine, calling the function doesn't work though.

EDIT: I've tried everything I can think of. Am I really missing something here or is there no way to use nl_relocdata on a pointer to a function? (I doubt it, even in the wiki it is mentioned)

[ExtendeD]

Things are getting complicated in your case, nl_relocdata was introduced to handle simpel cases, sorry about that.

I unfortunately cannot test them on this computer, but here are a few corrections:

- nl_relocdata((unsigned int *)bootstrap, sizeof(bootstrap) / sizeof(bootstrap[0]));: I'm not sure relocating NULL is a good idea. Use nl_relocdata((unsigned int *)bootstrap, 1); instead.
- nl_relocdata((unsigned int *)bootstrap[0]->fp, sizeof(void *));: Use nl_relocdata((unsigned int *)bootstrap[0]->fp, 1);

But anyway I'm not sure this will fix your error, I'll look further into this as soon as possible.

[hoffa]

Thanks, but it unfortunately did not fix it. What exactly does size refer to--what size does it refer to (in bytes I presume)? I'll experiment around a bit, but if there is no solution yet I will kindly wait for any future developments.

EDIT:
What do you mean relocating NULL? bootstrap is not NULL, nor is the quotient equal to zero.

[ExtendeD]

But bootstrap contains a NULL value, I'm not sure I'm skipping NULL values.

nl_relocdata relocates an array of pointers (it should work as well on entire structures containing only pointers). The second parameter corresponds to the number of pointers to relocate.

[alberthrocks]

Hmm... how hard will it be to write a BLFT loader? It seems that this project (and possibly many others) might need one.
It has code relocation and is much smaller than the ELF loader.

(If it isn't too hard, I might attempt to write one Seems that one would need to know ARM ASM to do it... which I don't know)

[ExtendeD]

Lionel Debroux has just started a port of the Linux implementation, he will post more about it.

[Lionel Debroux]

I have indeed started looking at what pieces need to be changed for porting Linux's bFLT loader (fs/binfmt_flat.c + include/linux/flat.h + arch/arm/include/asm/flat.h) to non-Linux OS running on the Nspire. And a quick examination (<1h) shows dozens of places that need to be adjusted; it's not necessarily very hard to do so, for the most part, it's just that someone needs to spend time doing it, and I don't have time to undertake such a task alone - for a start, not this evening.

ExtendeD has suggested looking at QEMU's loader (linux-user/flatload.c), which looks slightly more portable than Linux's loader. It remains quite tied to Linux/QEMU internals, and may or may not be a better starting point than Linux's loader: unlike Linux's loader, QEMU's loader's support for compressed binaries and for libraries is explicitly disabled - and we clearly want both, probably with a higher priority on libraries. Support for compressed bFLT binaries wouldn't cost much space in the loader, since we can (well, "ought to be able to") rely on the zlib functions embedded in the OS.

Seems that one would need to know ARM ASM to do it

I doubt that it's necessary: AFAICT, the bFLT loaders in Linux and QEMU are plain C


EDIT: here's the current state of the stuff. As you can see, I haven't changed the code yet, and won't do tonight. The tarball is made of five files:
* binfmt_flat_mod.c is Linux's bFLT loader, annotated with a bunch of TODOs on parts that we need to remove or port;
* binflt_flat.diff is the diff against the pristine file;
* the two headers are include/linux/flat.h and arch/arm/include/asm/flat.h;
* flatload.c is QEMU's bFLT loader.

[ExtendeD]

Could somebody quickly check my code, it doesn't seem to print the value of f. Either I'm using nl_relocdata wrong, or then I'm too tired and am missing something silly.

http://pastebin.com/N2iiUhd1

That's more or less how SDL behaves at one point, and it's reallocating the function pointer that causes issues. The strings print out fine, calling the function doesn't work though.

EDIT: I've tried everything I can think of. Am I really missing something here or is there no way to use nl_relocdata on a pointer to a function? (I doubt it, even in the wiki it is mentioned)

Here it is fixed: http://pastebin.com/ELBkWJMt

[hoffa]

Oh wow, thanks. I'm quite surprised as I tried the same code as you except without the &-operator; I thought prefixing a function name with the ampersand was optional, both should return the address of the said function AFAIK.

EDIT:
This is great news as I'm now able to initialize the barebone video driver:

[ExtendeD]

Good

Here the address of the field that contains the function pointer is expected, so the & is required.

[ExtendeD]

Good

Here the address of the field that contains the function pointer is expected, so the & is required.

[Jim Bauwens]

Nice to see the progress!

[DJ Omnimaga]

Good to hear hoffa. Hopefully this gets finished eventually.