(...) Right. The calling conventions of the H8 say that r0-r3 are scratch registers (aka caller saves). However, interrupt handlers must preserve ALL of the registers. So the rcx_interrupt attribute makes that happen. (...) The compiler will only (...) (25 years ago, 31-Jan-00, to lugnet.robotics.rcx.legos)
(...) Well, i got the definitive answer from Markus 8-). It was in german, so i'll try to translate it: the effect of __attribute__ ((rcx_interrrupt)) depends on the calling context: - in leaf functions (that do not call other functions), it makes (...) (25 years ago, 1-Feb-00, to lugnet.robotics.rcx.legos)