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batman-adv: Check type of x and y in seq_(before|after) 

seq_before and seq_after depend on the fact that both sequence numbers
have the same type and thus the same bitwidth. We can ensure that by
compile time checking using a compare between the pointer to the
temporary buffers which were created using the typeof of both
parameters. For example gcc would create a warning like
"warning: comparison of distinct pointer types lacks a cast".

Signed-off-by: Sven Eckelmann <sven@narfation.org>
This commit is contained in:
Sven Eckelmann 2011-05-19 21:43:08 +02:00
parent f5d33d3778
commit 0bb857511b
1 changed files with 5 additions and 2 deletions
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7
net/batman-adv/main.h
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@ -194,8 +194,11 @@ static inline int compare_eth(const void *data1, const void *data2)
* - before adding more than 127 to the starting value - it is a predecessor,
* - when adding 128 - it is neither a predecessor nor a successor,
* - after adding more than 127 to the starting value - it is a successor */
#define seq_before(x, y) ({typeof(x) _dummy = (x - y); \
_dummy > smallest_signed_int(_dummy); })
#define seq_before(x, y) ({typeof(x) _d1 = (x); \
typeof(y) _d2 = (y); \
typeof(x) _dummy = (_d1 - _d2); \
(void) (&_d1 == &_d2); \
_dummy > smallest_signed_int(_dummy); })
#define seq_after(x, y) seq_before(y, x)
#endif /* _NET_BATMAN_ADV_MAIN_H_ */