Newlib, gcc, adding a file system

The arm-none-eabi GCC port and it's accompanying newlib (I got mine from 
Codesourcery but I suspect this applies to all) clearly has hooks in it 
to add a filesystem into an application.

I've Googled around and haven't found anything that seems to really be 
definitive -- Is there any really good documentation on how to do this, 
preferably from the point of view of the newlib developers?

TIA.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Tim Wescott <seemywebsite@myfooter.really> writes:
> I've Googled around and haven't found anything that seems to really be 
> definitive -- Is there any really good documentation on how to do this, 
> preferably from the point of view of the newlib developers?

In the source tree, look in libgloss/ (sibling to newlib/).  There are
various implementations of the I/O layer, from "nosys" which does
nothing, to simulator syscalls, to various os-specific layers.  The
libgloss library lets you provide low-level
open/read/write/close/exit/etc functions.  Newlib's I/O functions (like
stdio) are built on top of these.

Most ports just have a write() equivalent that's used for debug printfs,
and exit().

Tim Wescott <seemywebsite@myfooter.really> writes:

> The arm-none-eabi GCC port and it's accompanying newlib (I got mine from 
> Codesourcery but I suspect this applies to all) clearly has hooks in it 
> to add a filesystem into an application.
>
> I've Googled around and haven't found anything that seems to really be 
> definitive -- Is there any really good documentation on how to do this, 
> preferably from the point of view of the newlib developers?

I referred to this when I did it:

http://www.cs.ccu.edu.tw/~pahsiung/courses/ese/resources/newlib.pdf

(It is rather old now)

In general it is probably a useful approach for larger projects. But it
does bring in all of stdio, malloc and so forth. So it can severely
bloat the code if you don't really need it.




-- 

John Devereux

On Fri, 06 Nov 2015 11:32:53 +0000, John Devereux wrote:

> Tim Wescott <seemywebsite@myfooter.really> writes:
> 
>> The arm-none-eabi GCC port and it's accompanying newlib (I got mine
>> from Codesourcery but I suspect this applies to all) clearly has hooks
>> in it to add a filesystem into an application.
>>
>> I've Googled around and haven't found anything that seems to really be
>> definitive -- Is there any really good documentation on how to do this,
>> preferably from the point of view of the newlib developers?
> 
> I referred to this when I did it:
> 
> http://www.cs.ccu.edu.tw/~pahsiung/courses/ese/resources/newlib.pdf
> 
> (It is rather old now)
> 
> In general it is probably a useful approach for larger projects. But it
> does bring in all of stdio, malloc and so forth. So it can severely
> bloat the code if you don't really need it.

What I'm doing qualifies as a "larger project" in that regard.  I'm using 
some off-the-shelf software that's going to be happier with stdio and 
malloc -- I'm probably saving work by at least a factor of 3:1, while 
using more memory at a factor of 5:1 or so.  At the anticipated sales 
volume for the product, it's worth it.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Il giorno gioved� 5 novembre 2015 19:39:09 UTC+1, Tim Wescott ha scritto:
> The arm-none-eabi GCC port and it's accompanying newlib (I got mine from 
> Codesourcery but I suspect this applies to all) clearly has hooks in it 
> to add a filesystem into an application.
> 
> I've Googled around and haven't found anything that seems to really be 
> definitive -- Is there any really good documentation on how to do this, 
> preferably from the point of view of the newlib developers?
> 
> TIA.

http://www.cs.ccu.edu.tw/~pahsiung/courses/ese/resources/newlib.pdf
page 7

Said so:
for an application I used FatFS:
http://elm-chan.org/fsw/ff/00index_e.html
you just have to implement the low level calls, it's quite straightforward.

Hope this helps

Bye Jack

Jack <jack4747@gmail.com> writes:

> Il giorno gioved&igrave; 5 novembre 2015 19:39:09 UTC+1, Tim Wescott ha scritto:
>> The arm-none-eabi GCC port and it's accompanying newlib (I got mine from 
>> Codesourcery but I suspect this applies to all) clearly has hooks in it 
>> to add a filesystem into an application.
>> 
>> I've Googled around and haven't found anything that seems to really be 
>> definitive -- Is there any really good documentation on how to do this, 
>> preferably from the point of view of the newlib developers?
>> 
>> TIA.
>
> http://www.cs.ccu.edu.tw/~pahsiung/courses/ese/resources/newlib.pdf
> page 7
>
> Said so:
> for an application I used FatFS:
> http://elm-chan.org/fsw/ff/00index_e.html
> you just have to implement the low level calls, it's quite straightforward.

I've used that too, a really nice little system, very easy to
incorporate into a project.

-- 

John Devereux

On Wednesday, November 11, 2015 at 11:59:07 AM UTC-5, John Devereux wrote:
> Jack <jack4747@gmail.com> writes:
> 
> > Il giorno gioved&#4294967295; 5 novembre 2015 19:39:09 UTC+1, Tim Wescott ha scritto:
> >> The arm-none-eabi GCC port and it's accompanying newlib (I got mine from 
> >> Codesourcery but I suspect this applies to all) clearly has hooks in it 
> >> to add a filesystem into an application.
> >> 
> >> I've Googled around and haven't found anything that seems to really be 
> >> definitive -- Is there any really good documentation on how to do this, 
> >> preferably from the point of view of the newlib developers?
> >> 
> >> TIA.
> >
> > http://www.cs.ccu.edu.tw/~pahsiung/courses/ese/resources/newlib.pdf
> > page 7
> >
> > Said so:
> > for an application I used FatFS:
> > http://elm-chan.org/fsw/ff/00index_e.html
> > you just have to implement the low level calls, it's quite straightforward.
> 
> I've used that too, a really nice little system, very easy to
> incorporate into a project.
> 
> -- 
> 
> John Devereux

Yup, I've also used the above pair; only a tiny bit of work to integrate.