Hello, I'm having trouble understanding the NOAREG, AREG & USING options. I'm also confused with R0-R7 & AR0-AR7. I've read the support files and manual but i'm still confused. May I know a) How is it that using NOAREGs will allow me to disregard register bank currently used when writing function? ( will the registers be automatically saved to stack? ) b) What is the difference with R0 and AR0? How does the USING option affect R0 & AR0? (for example if i put the option "USING 2", have then use R4, does this mean that it is the actually R20 ie in bank 2, whiel AR4 is not affected by the using function) c) How does USING help me to save stack space? Best Regards, AL
Hello, First of all I wanted to thank Cole for his excellent explanation. It clears a lot of the fog around this issue, and I think that this explanation should be entered into the manual ! I still have several questions regarding interrupt coding and relevant compiler directives: 1) Assuming the following code:
void UartIsr( void ) INTERRUPT(4) USING(2) { f1(); } #pragma NOAREGS void f1(void) { … … f2(); … … } #pragma AREGS void f2(void) { … … … }
And some more questions... Is it deafult compilation state to use AREG if no AREG/NOAREG pragma is written in the code ? Do I need to specify it in the beginning of main? If I specify any option (use AREG or NOAREG) at a specific place in the code, will this direction be relevant in all the following code (including called functions) untill a new direction will be issued ?
Please start a new thread for such generic questions.