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What is the L bit in the WAITX instruction and why can't I find it anywhere? — Parallax Forums

What is the L bit in the WAITX instruction and why can't I find it anywhere?

Peter JakackiPeter Jakacki Posts: 10,193
in Propeller 2
I must confess to having some brain fog today but nonetheless I usually tend to muddle through it. Not so today as I was playing with some simple assembler words in TAQOZ and performing an automatic AUGD without having to use ## etc. But looking at the bit fields for the WAITX instruction I can't for the life of me think what that does again and neither can I find it explained anywhere in the documentation and of course forum searching is useless too.

This is your chance to say to me "it's simple!" :) (which I'm sure it is).

Comments

  • Peter JakackiPeter Jakacki Posts: 10,193
    Struggling a bit more through that brain fog it seems like it must be the immediate field for the destination but still, the information about that is nowhere to be found.
  • ersmithersmith Posts: 6,053
    If I remember correctly, "L" is the name for the immediate bit when it applies to the destination field (which for some instructions, like waitx, is the only field). Some instructions only allow immediates on the source field (so they have only an I bit). Some instructions allow immediates on both source and destination (so they have both L and I bits).
  • evanhevanh Posts: 15,915
    I'd concur on meaning of L
    I don't think any of the bit-field letters are labelled. Everyone just sort of gets the idea as they go.
  • Peter JakackiPeter Jakacki Posts: 10,193
    evanh wrote: »
    I'd concur on meaning of L
    I don't think any of the bit-field letters are labelled. Everyone just sort of gets the idea as they go.

    Yeah, when I looked at the REP instruction I saw the I and L and thought it must be the immediate bit for the destination. Still though, it is not explained anywhere so I guess it should be noted in the first row of the instruction encoding column of the spreadsheet.
  • SeairthSeairth Posts: 2,474
    edited 2019-01-14 12:23
    That's correct. It's documented in cell E1 of the instruction spreadsheet.

    https://docs.google.com/spreadsheets/d/1usUcCCQVp3liAqENX9rvX-XVqJomMREhKYExM_taG0A/view

    Edit: I should have read the rest of the thread before responding. @"Peter Jakacki", the copy I linked has exactly what you suggest (and I thought it's been there quite a while). Which spreadsheet are you referring to?
  • Peter JakackiPeter Jakacki Posts: 10,193
    @Seairth - not so much fog now and I see it clearly enough :)

    BTW - same spreadsheet but I was over in D1.
  • Cluso99Cluso99 Posts: 18,069
    Yes, L is for #D (immediate D).
    It was probably discussed eons ago, but lost in the wash.
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