Re: Martin's expression for the item size of XGetWindowProperty buffers
>>>> "SJT" == Stephen J Turnbull
<turnbull(a)sk.tsukuba.ac.jp> writes:
SJT> I'm taking this off -patches, as I don't intend to do anything about it
SJT> immediately; in fact, I intend to wait for a request from Vin to port
SJT> to 21.4. :-) Anybody who wants to write up a patch, feel free!
SJT> Martin Buchholz writes:
> The "expansion factor" seems to be
>
> format == 8 ? CHAR_BIT / format :
> format == 16 ? SHORT_BIT / format :
> format == 32 ? LONG_BIT / format
>
> which can mostly portably be simplified to
>
> format == 32 ? LONG_BIT / 32 : 1;
SJT> Thanks! But I don't see the advantage to configure detection of
SJT> CHAR_BIT and friends; just use sizeof(type)*8. And for modern
SJT> compilers, optimization should result in your "mostly portable"
SJT> simplified form, right? (Maybe it would be best to start with
SJT> "format == 32 ? ..." for slightly stupid compilers?) Not that it
SJT> matters; this is surely going to be swamped by network latency.
I was not thinking at all about optimization.
Sure, LONG_BIT is exactly the same as sizeof(long)*CHAR_BIT.
Is it slightly more readable? If yes, then we should use it.
I generally prefer to use standardized symbols like LONG_BIT
if they are even slightly more convenient or readable,
fixing configure for platforms where they are not (yet) available.
Martin
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