Lpc2000

Greetings,
Im currently creating application with GCC 4.0.2 and i'd like to use 
THUMB code in IRQ (of course called from ARM ISR). My testing code 
is very simple - UART ISR setting volatile int and main() checking 
it and perfrorming sw LED blinking. When I translate all in ARM it 
does exactly what it should do. But when one of routines called from 
ISR is in THUMB it behaves quite strange: ISR takes much longer time 
(LED flashing is significantly slower) and after sending two 
characters with short time space, core generates data abort 
exception and freezes. But when i remove int checking from main(), 
data abort exception is not generated but code is still 
significantly slowed down by ISR. To me it seems like some problem 
with stack caused by differences between IRQ and system run mode of 
ARM7TDMI core, but im really not sure and i have neither debugging 
hw nor any idea how to solve it...

Thank's for any responses
Jan Svab
http://schvab.no-ip.com/