Modifying ARM syscalls.c for terminal I/O

Paul Griffin
Tue Feb 4 15:11:00 GMT 2003

Hi all,

i'm using gcc3.1.2 built for an arm-elf target running on a i686-pc-cygwin 
host. At present all I/O is achieved using my own arm assembly routines that 
make use of the on chip uart. I would now like to be able to use printf!! I 
do not have the use of Angel or Demon i/o services.

So far i've gathered that i need to modify libc/sys/arm/syscalls.c in order 
to achieve this. The approach i'm taking at the moment is to replace the 
function _swiwrite() with a function that would wrap my own assembly 
routine. The assembly routine simply bit bangs individual characters down 
the serial port.

My question is are my modifcations in the correct area? would anyone have 
any alternative suggestions to this "wrapper" approach???

Any suggestions or advice would be very much appreciated!


The new MSN 8: advanced junk mail protection and 2 months FREE*

More information about the Newlib mailing list