Is this link register masking needed?

I see some instructions like this :-

bic link, link, # &fc000003

and this

bic R0, link, # &fc000003

Is this mask likely to be related to 26 bit mode and no longer necessary now ?

That’s clearing the flag bits (the fc) and the mode bits (the 3) to extract the value of PC from the link register with combined PC and PSR.

So, yes, it’s a 26 bit thing.

May still be required if the code is to run in 26bit as well as 32bit modes?!

Thanks much appreciated.

@Martin far better to get rid of that entirely and make it 26/32 neutral rather than preserving any 26 bit only constructs.

Indeed – that is why I said ‘may’. Obviously better to avoid it.

I think it depends what the context is, why extracting PC is happening here. Maybe something like:

TEQ   R0, R0
TEQ   PC, PC
MOVEQ R0, LR             ; 32 bit
BICNE R0, LR, #&FC000003 ; 26 bit

(I’m in bed and half asleep, so I hope I have the EQ and NE the right way around)

There are some insightful points in the discussion I find very helpful. I will try/test some options.

For the curious: just attempting a spot of rennovation to a FORTH.

This has its own built in assembler PASM.
https://github.com/alban-read/forth/blob/master/PASM

Used a lot in FORTH kernel and everywhere else..
https://github.com/alban-read/forth/blob/master/FKERNEL