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Since GCC 4.4, there have been __builtin_bswap32() and __builtin_bswap16() intrinsics. A __builtin_bswap16() came a little later (4.6 for PowerPC, 48 for other platforms). By using these instead of the inline assembler that most architectures have in their __arch_swabXX() macros, we let the compiler see what's actually happening. The resulting code should be at least as good, and much *better* in the cases where it can be combined with a nearby load or store, using a load-and-byteswap or store-and-byteswap instruction (e.g. lwbrx/stwbrx on PowerPC, movbe on Atom). When GCC is sufficiently recent *and* the architecture opts in to using the intrinsics by setting CONFIG_ARCH_USE_BUILTIN_BSWAP, they will be used in preference to the __arch_swabXX() macros. An architecture which does not set ARCH_USE_BUILTIN_BSWAP will continue to use its own hand-crafted macros. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Acked-by: H. Peter Anvin <hpa@linux.intel.com>
289 lines
6.4 KiB
C
289 lines
6.4 KiB
C
#ifndef _UAPI_LINUX_SWAB_H
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#define _UAPI_LINUX_SWAB_H
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#include <linux/types.h>
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#include <linux/compiler.h>
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#include <asm/swab.h>
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/*
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* casts are necessary for constants, because we never know how for sure
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* how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
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*/
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#define ___constant_swab16(x) ((__u16)( \
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(((__u16)(x) & (__u16)0x00ffU) << 8) | \
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(((__u16)(x) & (__u16)0xff00U) >> 8)))
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#define ___constant_swab32(x) ((__u32)( \
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(((__u32)(x) & (__u32)0x000000ffUL) << 24) | \
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(((__u32)(x) & (__u32)0x0000ff00UL) << 8) | \
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(((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | \
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(((__u32)(x) & (__u32)0xff000000UL) >> 24)))
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#define ___constant_swab64(x) ((__u64)( \
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(((__u64)(x) & (__u64)0x00000000000000ffULL) << 56) | \
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(((__u64)(x) & (__u64)0x000000000000ff00ULL) << 40) | \
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(((__u64)(x) & (__u64)0x0000000000ff0000ULL) << 24) | \
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(((__u64)(x) & (__u64)0x00000000ff000000ULL) << 8) | \
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(((__u64)(x) & (__u64)0x000000ff00000000ULL) >> 8) | \
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(((__u64)(x) & (__u64)0x0000ff0000000000ULL) >> 24) | \
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(((__u64)(x) & (__u64)0x00ff000000000000ULL) >> 40) | \
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(((__u64)(x) & (__u64)0xff00000000000000ULL) >> 56)))
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#define ___constant_swahw32(x) ((__u32)( \
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(((__u32)(x) & (__u32)0x0000ffffUL) << 16) | \
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(((__u32)(x) & (__u32)0xffff0000UL) >> 16)))
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#define ___constant_swahb32(x) ((__u32)( \
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(((__u32)(x) & (__u32)0x00ff00ffUL) << 8) | \
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(((__u32)(x) & (__u32)0xff00ff00UL) >> 8)))
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/*
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* Implement the following as inlines, but define the interface using
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* macros to allow constant folding when possible:
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* ___swab16, ___swab32, ___swab64, ___swahw32, ___swahb32
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*/
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static inline __attribute_const__ __u16 __fswab16(__u16 val)
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{
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#ifdef __HAVE_BUILTIN_BSWAP16__
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return __builtin_bswap16(val);
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#elif defined (__arch_swab16)
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return __arch_swab16(val);
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#else
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return ___constant_swab16(val);
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#endif
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}
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static inline __attribute_const__ __u32 __fswab32(__u32 val)
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{
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#ifdef __HAVE_BUILTIN_BSWAP32__
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return __builtin_bswap32(val);
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#elif defined(__arch_swab32)
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return __arch_swab32(val);
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#else
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return ___constant_swab32(val);
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#endif
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}
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static inline __attribute_const__ __u64 __fswab64(__u64 val)
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{
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#ifdef __HAVE_BUILTIN_BSWAP64__
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return __builtin_bswap64(val);
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#elif defined (__arch_swab64)
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return __arch_swab64(val);
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#elif defined(__SWAB_64_THRU_32__)
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__u32 h = val >> 32;
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__u32 l = val & ((1ULL << 32) - 1);
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return (((__u64)__fswab32(l)) << 32) | ((__u64)(__fswab32(h)));
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#else
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return ___constant_swab64(val);
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#endif
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}
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static inline __attribute_const__ __u32 __fswahw32(__u32 val)
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{
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#ifdef __arch_swahw32
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return __arch_swahw32(val);
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#else
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return ___constant_swahw32(val);
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#endif
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}
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static inline __attribute_const__ __u32 __fswahb32(__u32 val)
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{
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#ifdef __arch_swahb32
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return __arch_swahb32(val);
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#else
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return ___constant_swahb32(val);
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#endif
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}
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/**
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* __swab16 - return a byteswapped 16-bit value
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* @x: value to byteswap
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*/
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#define __swab16(x) \
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(__builtin_constant_p((__u16)(x)) ? \
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___constant_swab16(x) : \
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__fswab16(x))
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/**
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* __swab32 - return a byteswapped 32-bit value
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* @x: value to byteswap
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*/
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#define __swab32(x) \
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(__builtin_constant_p((__u32)(x)) ? \
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___constant_swab32(x) : \
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__fswab32(x))
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/**
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* __swab64 - return a byteswapped 64-bit value
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* @x: value to byteswap
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*/
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#define __swab64(x) \
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(__builtin_constant_p((__u64)(x)) ? \
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___constant_swab64(x) : \
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__fswab64(x))
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/**
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* __swahw32 - return a word-swapped 32-bit value
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* @x: value to wordswap
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*
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* __swahw32(0x12340000) is 0x00001234
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*/
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#define __swahw32(x) \
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(__builtin_constant_p((__u32)(x)) ? \
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___constant_swahw32(x) : \
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__fswahw32(x))
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/**
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* __swahb32 - return a high and low byte-swapped 32-bit value
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* @x: value to byteswap
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*
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* __swahb32(0x12345678) is 0x34127856
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*/
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#define __swahb32(x) \
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(__builtin_constant_p((__u32)(x)) ? \
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___constant_swahb32(x) : \
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__fswahb32(x))
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/**
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* __swab16p - return a byteswapped 16-bit value from a pointer
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* @p: pointer to a naturally-aligned 16-bit value
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*/
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static inline __u16 __swab16p(const __u16 *p)
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{
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#ifdef __arch_swab16p
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return __arch_swab16p(p);
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#else
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return __swab16(*p);
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#endif
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}
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/**
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* __swab32p - return a byteswapped 32-bit value from a pointer
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* @p: pointer to a naturally-aligned 32-bit value
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*/
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static inline __u32 __swab32p(const __u32 *p)
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{
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#ifdef __arch_swab32p
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return __arch_swab32p(p);
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#else
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return __swab32(*p);
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#endif
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}
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/**
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* __swab64p - return a byteswapped 64-bit value from a pointer
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* @p: pointer to a naturally-aligned 64-bit value
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*/
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static inline __u64 __swab64p(const __u64 *p)
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{
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#ifdef __arch_swab64p
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return __arch_swab64p(p);
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#else
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return __swab64(*p);
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#endif
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}
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/**
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* __swahw32p - return a wordswapped 32-bit value from a pointer
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* @p: pointer to a naturally-aligned 32-bit value
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*
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* See __swahw32() for details of wordswapping.
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*/
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static inline __u32 __swahw32p(const __u32 *p)
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{
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#ifdef __arch_swahw32p
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return __arch_swahw32p(p);
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#else
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return __swahw32(*p);
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#endif
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}
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/**
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* __swahb32p - return a high and low byteswapped 32-bit value from a pointer
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* @p: pointer to a naturally-aligned 32-bit value
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*
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* See __swahb32() for details of high/low byteswapping.
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*/
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static inline __u32 __swahb32p(const __u32 *p)
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{
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#ifdef __arch_swahb32p
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return __arch_swahb32p(p);
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#else
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return __swahb32(*p);
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#endif
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}
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/**
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* __swab16s - byteswap a 16-bit value in-place
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* @p: pointer to a naturally-aligned 16-bit value
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*/
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static inline void __swab16s(__u16 *p)
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{
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#ifdef __arch_swab16s
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__arch_swab16s(p);
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#else
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*p = __swab16p(p);
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#endif
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}
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/**
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* __swab32s - byteswap a 32-bit value in-place
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* @p: pointer to a naturally-aligned 32-bit value
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*/
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static inline void __swab32s(__u32 *p)
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{
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#ifdef __arch_swab32s
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__arch_swab32s(p);
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#else
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*p = __swab32p(p);
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#endif
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}
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/**
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* __swab64s - byteswap a 64-bit value in-place
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* @p: pointer to a naturally-aligned 64-bit value
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*/
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static inline void __swab64s(__u64 *p)
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{
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#ifdef __arch_swab64s
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__arch_swab64s(p);
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#else
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*p = __swab64p(p);
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#endif
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}
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/**
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* __swahw32s - wordswap a 32-bit value in-place
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* @p: pointer to a naturally-aligned 32-bit value
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*
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* See __swahw32() for details of wordswapping
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*/
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static inline void __swahw32s(__u32 *p)
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{
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#ifdef __arch_swahw32s
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__arch_swahw32s(p);
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#else
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*p = __swahw32p(p);
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#endif
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}
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/**
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* __swahb32s - high and low byteswap a 32-bit value in-place
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* @p: pointer to a naturally-aligned 32-bit value
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*
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* See __swahb32() for details of high and low byte swapping
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*/
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static inline void __swahb32s(__u32 *p)
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{
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#ifdef __arch_swahb32s
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__arch_swahb32s(p);
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#else
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*p = __swahb32p(p);
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#endif
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}
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#endif /* _UAPI_LINUX_SWAB_H */
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