After some work with RTX-tiny, I have taken the following note: In RTX166-Tiny, the use of local (auto) variables is strongly impaired. RTX-Tiny shifts the contents of the stacks (user and system stack) at run-time. This can occur with any context-switch. This stack shift renders all pointers to variables on the user stack invalid. This concerns all pointers to variables declared within functions (without the declarator 'static') whether they were produced by the programmer or by the compiler. Only the use of the basic types char, int, bit and their unsigned variants is safe. The compiler adresses arrays and structures by pointers. Hence the use of those types is unsafe. The types long, float and doubles were not examined here. By switching off round-robin multitasking, the location of the context-switch is exactly specified. Within sequences with no context-switch, the use of 'unsafe' types is then permissible. My question to all who did use RTX-tiny: How did you get around this problems? Did I miss some important information?
I posted a similar question to keil support, and meanwhile I got this answer: -------------------------------------------- beim struct return werden Pointer benutzt. Wenn die struct lokal definiert ist gibt es die in \keil\c166\rtx_tiny\readme.txt beschriebenen Probleme. Loesung: definieren Sie die struct ausserhalb der Funktion, damit der struct return klappt. -------------------------------------------- This is indeed what I learnt by experience. Since I can't make use of static variables - my app concurrently runs several instances of the same function - I've had to find another solution. Now I have defined data channels (indeed static structures) for the return values of every instance. This of course works, but is not as friendly as with local structs.