Messages in this thread | | | Subject | Re: [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers | From | Johannes Berg <> | Date | Wed, 24 Nov 2021 15:07:47 +0100 |
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On Wed, 2021-11-24 at 05:59 -0800, Jakub Kicinski wrote: > > FWIW I never found the be/le versions useful. Most of the time the data > comes from bus accessors which swap or is unaligned so you have to do > be/le_get_unaligned, which swaps. Plus if you access/set multiple > fields you'd swap them one by one which seems wasteful.
Oh, we use them all the time in wifi!
I'm not sure I'm too concerned about wasteful - actually in wifi most of the time it's little endian to start with, which matches the CPU for all practical uses of wifi (**), and often we just access one field or so. And anyway if we extract more than a single bit we need to swap anyway, and I hope if it's just a single bit the compiler will optimize since the one side is a constant? But whatever ...
(**) I had a fight with big-endian ARM a few years ago just to get wifi tested on big-endian ...
> Right now it seems the uppercase macros are more prevalent. >
Not in my world ;-)
$ git grep FIELD_GET -- ... | wc -l 20 $ git grep le32_get_bits -- ... | wc -l 44 $ git grep le16_get_bits -- ... | wc -l 12 $ git grep u8_get_bits -- ... | wc -l 17
:-)
johannes
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