#if defined __GNUC__ && __GNUC__ >= 2
# define __bswap_16(x) \
(__extension__ \
- ({ register unsigned short int __v, __x = (x); \
+ ({ register unsigned short int __v, __x = (unsigned short int) (x); \
if (__builtin_constant_p (x)) \
__v = __bswap_constant_16 (__x); \
else \