On 2013-01-07 12:22 AM, Xiaofan Chen wrote:
>> Why not use xc32 itself? It is now available under Windows, Linux
>> and Mac OS X. Okay, the optimization is not as good as
>> the full version after the evaluation time out, but the basic
>> gcc optimization will still be there.

I am using clang and LLVM at the moment. I really like the concept
behind LLVM. Clang reads standard C code, then outputs LLVM bytecode,
which is then optimized. LLVM is dynamically retargetable, so it is
simple to output mips32r2 assembler code.

This is where GNU binutils comes in. `as` compiles the mips32r2 code
into object files which are then linked by `ld`.

The last piece of the puzzle is to try and get `as` or `ld` to put
static config data at the specified address in the linker script.

I'm sure it can be done, but I just don't know how. I don't know where
and how to specify the static data so that it can be placed at the
proper address in the hex image.

>> If not, what about build xc32 (or C32) compiler by yourself using
>> the source codes?
>> Eg:
>> http://www.microchip.com/forums/m692454.aspx
>> http://www.microchip.com/forums/m579695.aspx
>> http://www.microchip.com/forums/m460901.aspx
>>
>> Technically you may still not able to use Microchip header files
>> and library files, but you can install xc32 under Linux and
>> the use those files.

I have considered it, but I really like LLVM and only one last, tiny
thing needs to be done to provide a completely free toolchain. I don't
want to have to rely on Microchip to provide optimization when LLVM's
bytecode optimizer is quite good already and only improving.

There are plenty of small C libraries for embedded use already so the
libraries aren't a big deal.

The headers are merely definitions of addresses and names which can be
reordered, changed up a bit by an automatic script and labelled as GNU
GPL. No big deal. The entirety of the data is in the datasheet anyway,
so you can't really stick a license on that anyway.

> So a fully open source toolchain will be to use xc32 open
> source toolchain and then ported another library (eg:
> newlib or uclibc or things like that) to the open source
> toolchain. I doubt that there will be many audiences
> now that xc32 works under Linux and Mac OS X,
> albeit will less optimization. But even if you build
> another library, the optimization may not be good
> as the xc32 libraries (some of them are from proprietary
> sources -- eg: MIPS).
>=20
> Ref: http://www.microchip.com/forums/tm.aspx?&m=3D364626
>=20

--=20
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