swab.h

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#ifndef _UAPI_LINUX_SWAB_H
#define _UAPI_LINUX_SWAB_H

#include <linux/types.h>
#include <linux/compiler.h>
#include <asm/swab.h>

/*
 * casts are necessary for constants, because we never know how for sure
 * how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
 */
#define ___constant_swab16(x) ((__u16)(             \
    (((__u16)(x) & (__u16)0x00ffU) << 8) |          \
    (((__u16)(x) & (__u16)0xff00U) >> 8)))

#define ___constant_swab32(x) ((__u32)(             \
    (((__u32)(x) & (__u32)0x000000ffUL) << 24) |        \
    (((__u32)(x) & (__u32)0x0000ff00UL) <<  8) |        \
    (((__u32)(x) & (__u32)0x00ff0000UL) >>  8) |        \
    (((__u32)(x) & (__u32)0xff000000UL) >> 24)))

#define ___constant_swab64(x) ((__u64)(             \
    (((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) |   \
    (((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) |   \
    (((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) |   \
    (((__u64)(x) & (__u64)0x00000000ff000000ULL) <<  8) |   \
    (((__u64)(x) & (__u64)0x000000ff00000000ULL) >>  8) |   \
    (((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) |   \
    (((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) |   \
    (((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56)))

#define ___constant_swahw32(x) ((__u32)(            \
    (((__u32)(x) & (__u32)0x0000ffffUL) << 16) |        \
    (((__u32)(x) & (__u32)0xffff0000UL) >> 16)))

#define ___constant_swahb32(x) ((__u32)(            \
    (((__u32)(x) & (__u32)0x00ff00ffUL) << 8) |     \
    (((__u32)(x) & (__u32)0xff00ff00UL) >> 8)))

/*
 * Implement the following as inlines, but define the interface using
 * macros to allow constant folding when possible:
 * ___swab16, ___swab32, ___swab64, ___swahw32, ___swahb32
 */

static inline __attribute_const__ __u16 __fswab16(__u16 val)
{
#ifdef __arch_swab16
    return __arch_swab16(val);
#else
    return ___constant_swab16(val);
#endif
}

static inline __attribute_const__ __u32 __fswab32(__u32 val)
{
#ifdef __arch_swab32
    return __arch_swab32(val);
#else
    return ___constant_swab32(val);
#endif
}

static inline __attribute_const__ __u64 __fswab64(__u64 val)
{
#ifdef __arch_swab64
    return __arch_swab64(val);
#elif defined(__SWAB_64_THRU_32__)
    __u32 h = val >> 32;
    __u32 l = val & ((1ULL << 32) - 1);
    return (((__u64)__fswab32(l)) << 32) | ((__u64)(__fswab32(h)));
#else
    return ___constant_swab64(val);
#endif
}

static inline __attribute_const__ __u32 __fswahw32(__u32 val)
{
#ifdef __arch_swahw32
    return __arch_swahw32(val);
#else
    return ___constant_swahw32(val);
#endif
}

static inline __attribute_const__ __u32 __fswahb32(__u32 val)
{
#ifdef __arch_swahb32
    return __arch_swahb32(val);
#else
    return ___constant_swahb32(val);
#endif
}

#define __swab16(x)             \
    (__builtin_constant_p((__u16)(x)) ? \
    ___constant_swab16(x) :         \
    __fswab16(x))

#define __swab32(x)             \
    (__builtin_constant_p((__u32)(x)) ? \
    ___constant_swab32(x) :         \
    __fswab32(x))

#define __swab64(x)             \
    (__builtin_constant_p((__u64)(x)) ? \
    ___constant_swab64(x) :         \
    __fswab64(x))

#define __swahw32(x)                \
    (__builtin_constant_p((__u32)(x)) ? \
    ___constant_swahw32(x) :        \
    __fswahw32(x))

#define __swahb32(x)                \
    (__builtin_constant_p((__u32)(x)) ? \
    ___constant_swahb32(x) :        \
    __fswahb32(x))

static inline __u16 __swab16p(const __u16 *p)
{
#ifdef __arch_swab16p
    return __arch_swab16p(p);
#else
    return __swab16(*p);
#endif
}

static inline __u32 __swab32p(const __u32 *p)
{
#ifdef __arch_swab32p
    return __arch_swab32p(p);
#else
    return __swab32(*p);
#endif
}

static inline __u64 __swab64p(const __u64 *p)
{
#ifdef __arch_swab64p
    return __arch_swab64p(p);
#else
    return __swab64(*p);
#endif
}

static inline __u32 __swahw32p(const __u32 *p)
{
#ifdef __arch_swahw32p
    return __arch_swahw32p(p);
#else
    return __swahw32(*p);
#endif
}

static inline __u32 __swahb32p(const __u32 *p)
{
#ifdef __arch_swahb32p
    return __arch_swahb32p(p);
#else
    return __swahb32(*p);
#endif
}

static inline void __swab16s(__u16 *p)
{
#ifdef __arch_swab16s
    __arch_swab16s(p);
#else
    *p = __swab16p(p);
#endif
}
static inline void __swab32s(__u32 *p)
{
#ifdef __arch_swab32s
    __arch_swab32s(p);
#else
    *p = __swab32p(p);
#endif
}

static inline void __swab64s(__u64 *p)
{
#ifdef __arch_swab64s
    __arch_swab64s(p);
#else
    *p = __swab64p(p);
#endif
}

static inline void __swahw32s(__u32 *p)
{
#ifdef __arch_swahw32s
    __arch_swahw32s(p);
#else
    *p = __swahw32p(p);
#endif
}

static inline void __swahb32s(__u32 *p)
{
#ifdef __arch_swahb32s
    __arch_swahb32s(p);
#else
    *p = __swahb32p(p);
#endif
}


#endif /* _UAPI_LINUX_SWAB_H */