where does "CARD18" come from?
Jamey Sharp
jamey at minilop.net
Sun May 19 23:02:51 PDT 2013
They're defined in the X11 core protocol specification:
http://www.x.org/releases/X11R7.7/doc/xproto/x11protocol.html#Common_Types
I believe "CARD" is short for "cardinal", as in "cardinal numbers".
Regarding X vs. Lisp: I've been told that the X design decision to make
XIDs 29 bits wide was because (at least some) Lisp implementations of
the day had 29-bit integers; the other bits in each word were used to
tag pointers vs. unboxed integers, I guess. So they're not so completely
unrelated as you might think.
Jamey
On Mon, May 20, 2013 at 07:12:44AM +0200, wempwer at gmail.com wrote:
> Hello,
>
> I was wondering where the names of various data types listed here may
> come from:
> http://www.x.org/wiki/XSessionManagementProtocol#Data_Types
>
> Most of them are clear, but these ones picked my interest:
>
> CARD8
> a one-byte unsigned integer
>
> CARD16
> a two-byte unsigned integer
>
> CARD32
> a four-byte unsigned integer
>
> Do you know what is the etymology of these type names? Do they mean
> "character...", but what does "d" stand for? In Lisp "car" is a
> function that returns the first element of the list but I think Xorg
> has nothing to do with Lisp.
>
> History is interesting ;)
> --
> <wempwer at gmail.com>
> _______________________________________________
> xorg-devel at lists.x.org: X.Org development
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