Re: [avr-libc-dev] <ot> porting a generic libc to an arbitrary uC

[Steve Franks]

All,

Just to close out this thread, I've discovered the process is very
similar, just completely undocumented (someone needs to beat someone
over the head with doxygen, or even put a comment in the stdio.h file,
something! anything!).

If you ever find yourself in this situation:

* google WinARM (even for unix users - you are stealing code, not installing it)
* download WinARM and unzip it somewhere
* search the <unzip>/examples directory for syscalls.c and serial.c
* modify them for your processor/pcb
* compile/link with them
* note that "iprintf()" on ARM is the rough equivalent of specifying
one of the watered-down vsprintf's in your makefile for AVR.
* note that if you find "rprintf()" in the code you are looking at,
move on to another example - rprintf appears to be the defacto
standard on ARM for anyone who wants to write a 'fake' printf function
with no stdio.h or libc.a linkage.
* beware that the syscalls.c file has a comment mentionins that it was
adapted from Keil's gcc toolset, and so may have unpleasant copyright
strings attached, even though none are mentioned specifically - I am
looking into it myself.

That's what I've found.  Hope it helps someone else.  Note that gnuarm
also requires a crt0.S file and .ld scripts in addition to a makefile
to generate a usable .hex.  You might steal those from WinARM while
you are at it.  Note they usually need customized as well - no nice
coordinated efforts like avr-libc to make everything work "out of the
box".

Steve