| Message ID | 1335360431-30027-4-git-send-email-ordex@autistici.org |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
> +/* Returns the biggest unsigned integer with the sizeof x */ > +#define biggest_unsigned_int(x) (~(x)0) Nope - biggest_unsigned_int(unsigned char) is probably 0xffffffff David -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> > +/* Returns the biggest unsigned integer with the sizeof x */ > > +#define biggest_unsigned_int(x) (~(x)0) > > Nope - biggest_unsigned_int(unsigned char) is probably 0xffffffff To correct myself, it is actually ((int)(-1)) (ie a signed value). David -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: "David Laight" <David.Laight@ACULAB.COM> Date: Wed, 25 Apr 2012 15:57:39 +0100 > >> > +/* Returns the biggest unsigned integer with the sizeof x */ >> > +#define biggest_unsigned_int(x) (~(x)0) >> >> Nope - biggest_unsigned_int(unsigned char) is probably 0xffffffff > > To correct myself, it is actually ((int)(-1)) (ie a signed value). In any event this is just a terrible macro, and too stupid to live. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Il 25.04.2012 20:09 David Miller ha scritto: > From: "David Laight" <David.Laight@ACULAB.COM> > Date: Wed, 25 Apr 2012 15:57:39 +0100 > >> >>> > +/* Returns the biggest unsigned integer with the sizeof x */ >>> > +#define biggest_unsigned_int(x) (~(x)0) >>> >>> Nope - biggest_unsigned_int(unsigned char) is probably 0xffffffff >> >> To correct myself, it is actually ((int)(-1)) (ie a signed value). > > In any event this is just a terrible macro, and too stupid to live. Hello David, ok. So the suggestion is to directly use the ~ operator in the code without creating a macro. If the rest of the patchset is ok, I will eliminate this macro and resend the pull request again. Cheers,
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h index a2b18d0..d9ef4ca 100644 --- a/net/batman-adv/main.h +++ b/net/batman-adv/main.h @@ -221,6 +221,9 @@ static inline bool has_timed_out(unsigned long timestamp, unsigned int timeout) /* Returns the smallest signed integer in two's complement with the sizeof x */ #define smallest_signed_int(x) (1u << (7u + 8u * (sizeof(x) - 1u))) +/* Returns the biggest unsigned integer with the sizeof x */ +#define biggest_unsigned_int(x) (~(x)0) + /* Checks if a sequence number x is a predecessor/successor of y. * they handle overflows/underflows and can correctly check for a * predecessor/successor unless the variable sequence number has grown by
in case of dynamic type variable, it could be needed to compute at compile time its maximal value. This macro helps in doing that for unsigned integer types Signed-off-by: Antonio Quartulli <ordex@autistici.org> --- net/batman-adv/main.h | 3 +++ 1 file changed, 3 insertions(+)