WP 34S and 31S bugs and fixes

[Bit]

(01-12-2015 01:14 AM)Paul Dale Wrote:  

(01-12-2015 12:48 AM)Bit Wrote:  This wouldn't be difficult to change if that's desired, see the patch below. Solve and integrate could probably be adapted in a similar way. (STOS/RCLS aren't currently used by any XROM routines so it's safe to change their behavior when called from XROM.)

For consistency, f' and f" should also do the same and likely solve and integrate.

Should the stack or some portion of it be preserved when passed to the user's routine? What if that routine makes changes? Currently, A .. D aren't changed and aren't filled by these and the user can do what they want with them even if they are in the stack.


- Pauli

I think XEQUSR does currently fill the whole stack (including A .. D if using an 8-level stack) before executing the user's routine, but correct me if I'm wrong. do_usergsb() calls usergsb_common() before calling fill(), and usergsb_common() moves the program counter out of the XROM area.

Filling the stack is consistent with what some HP calculators do and IMO it's the right thing to do as the user's routine shouldn't assume anything about the stack other than it contains the input. Restoring the whole stack after the sum etc. functions return would make sense and if the user's routine needs additional storage, it should use registers that aren't part of the stack.