___constant_swab16
#define __constant_cpu_to_le16(x) ((__force __le16)___constant_swab16((x)))
#define __constant_le16_to_cpu(x) ___constant_swab16((__force __u16)(__le16)(x))
#define __constant_htons(x) ((__force __be16)___constant_swab16((x)))
#define __constant_ntohs(x) ___constant_swab16((__force __be16)(x))
#define __constant_cpu_to_be16(x) ((__force __be16)___constant_swab16((x)))
#define __constant_be16_to_cpu(x) ___constant_swab16((__force __u16)(__be16)(x))
___constant_swab16(x) : \
return ___constant_swab16(val);