On Fri, 14 Jan 2011, Garrett Cooper wrote:
On Fri, Jan 14, 2011 at 6:42 PM, Bruce Evans <b...@optusnet.com.au> wrote:
On Fri, 14 Jan 2011 m...@freebsd.org wrote:
On Thu, Jan 13, 2011 at 10:50 PM, Bruce Evans <b...@optusnet.com.au>
wrote:
On Thu, 13 Jan 2011 m...@freebsd.org wrote:
There appear to be 330 uses of SYSCTL and QUAD on the same line in
CURRENT. ?This seems reasonable to change them to S64, U64 and X64 so
they correctly reflect the size they operate upon.
What do y'all think?
Now I suggest delaying this until they can be renamed to a type- generic
SYSCTL_INT() (would probably need to be spelled differently, SYSCTL_I()
say, even if SYSCTL_INT() was changed at the same time).
I'm torn on this one. ?The compiler knows the type (unless, for
SYSCTL_INT, NULL/0 is used, but that is also a compile-time check),
but to interpret it requires the use of __builtin_foo which is a gcc
extension and not part of standard C.
Philosophically, while I like this kind of letting the compiler do the
work, if you want C++ you know where to find it.
Oops. ?I think sizeof() and issigned() can be used to determine the type
well enough in functions and initialized data (do a fuller type check if
the compiler supports it), but I don't know how to do this in static
sysctl declarations (since sizeof() can't be used in cpp expressions).
Why not just create some dumb testcases that can be run at build
time to determine that for you?
Well, how? You are given SYSCTL_I(&var, ...) and have to convert this
to what is now in SYSCTL_INT(), using only the type of var, in hundreds
or thousands of files. I don't even know how to do this with a test
case for each file, short of parsing all the files. Oops, I do know
how to translate from sizeof(var) to CTLTYPE_INT or CTLTYPE_UINT.
That's just (sizeof(var) == sizeof(int) ? CTLTYPE_INT : ...). The
signness is harder (might need gnu typeof(), but not the recent type
checking attributes). This won't convert from SYSCTL_I() existing
SYSCTL_INT() (the switch on the size would have to be in an ifdef for
that, but sizeof() doesn't work in ifdefs), but it works for generating
CTLTYPE_* internally SYSCTL_I(). The difficulty is converting from a
bare variable `var' to an integer representing the signedness of its
type, without using an unportability like typeof(). With typeof(), this
is:
/* Only works for arithmetic types: */
#define isinteger(var) ((typeof(var))0.1 == 0)
#define issigned(var) ((typeof(var))-1 < 0)
...
Bruce_______________________________________________
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