In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Zoot wrote:

On my ISR-based SX projects, I generally use a NOPRESERVE for the ISR and assembly.

However, I have one project where I want to use the param registers in both the ISR and the mainline program.

In looking over generated source code in SX/B, I noticed a few things that I need clarification on:

- it appears that only PARAM1 - PARAM4 are preserved in the INTPARAMFSR registers; PARAM5 (aka __PARAMCNT) does NOT appear to be preserved. Since it seems to be common practice in SX/B to use __PARAMCNT, it would seem that if an interrupt occurs during the first few lines of something like the following, then you could be trouble. Or am I missing something? I generally use ASM and do not use the param registers in my ISRs, but still...

[code]
SomeSub:
   IF __PARAMCNT = 1 THEN
     tmpW1 = __PARAM1 ' if interrupt occurs here, and paramcnt is used by SX/B operations in the ISR, then it could get mucked up
   ELSEIF __PARAMCNT = 2 THEN
     tmpW1 = __PARAMW12
   ENDIF
[/code]

- since PARAMS are "preserved" in the __INTPARAMFSR registers during an interrupt, IF I AM DECLARING NOPRESERVE, it looks like I could claim back these registers for my own purposes? It appears (in my generated .src output anyway) that __INTPARAMFSR is declared and the var space is assigned whether or not is used?

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