e0487992ce
This patch comments the fact that although passing le64_to_cpup et al. is within the intended use of the byteorder macros, using get_unaligned is the recommended way to go. Signed-off-by: Ed L. Cashin <ecashin@coraid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
176 lines
5.7 KiB
C
176 lines
5.7 KiB
C
#ifndef _LINUX_BYTEORDER_GENERIC_H
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#define _LINUX_BYTEORDER_GENERIC_H
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/*
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* linux/byteorder_generic.h
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* Generic Byte-reordering support
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*
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* The "... p" macros, like le64_to_cpup, can be used with pointers
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* to unaligned data, but there will be a performance penalty on
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* some architectures. Use get_unaligned for unaligned data.
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*
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* Francois-Rene Rideau <fare@tunes.org> 19970707
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* gathered all the good ideas from all asm-foo/byteorder.h into one file,
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* cleaned them up.
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* I hope it is compliant with non-GCC compilers.
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* I decided to put __BYTEORDER_HAS_U64__ in byteorder.h,
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* because I wasn't sure it would be ok to put it in types.h
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* Upgraded it to 2.1.43
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* Francois-Rene Rideau <fare@tunes.org> 19971012
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* Upgraded it to 2.1.57
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* to please Linus T., replaced huge #ifdef's between little/big endian
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* by nestedly #include'd files.
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* Francois-Rene Rideau <fare@tunes.org> 19971205
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* Made it to 2.1.71; now a facelift:
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* Put files under include/linux/byteorder/
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* Split swab from generic support.
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*
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* TODO:
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* = Regular kernel maintainers could also replace all these manual
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* byteswap macros that remain, disseminated among drivers,
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* after some grep or the sources...
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* = Linus might want to rename all these macros and files to fit his taste,
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* to fit his personal naming scheme.
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* = it seems that a few drivers would also appreciate
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* nybble swapping support...
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* = every architecture could add their byteswap macro in asm/byteorder.h
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* see how some architectures already do (i386, alpha, ppc, etc)
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* = cpu_to_beXX and beXX_to_cpu might some day need to be well
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* distinguished throughout the kernel. This is not the case currently,
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* since little endian, big endian, and pdp endian machines needn't it.
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* But this might be the case for, say, a port of Linux to 20/21 bit
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* architectures (and F21 Linux addict around?).
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*/
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/*
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* The following macros are to be defined by <asm/byteorder.h>:
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*
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* Conversion of long and short int between network and host format
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* ntohl(__u32 x)
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* ntohs(__u16 x)
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* htonl(__u32 x)
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* htons(__u16 x)
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* It seems that some programs (which? where? or perhaps a standard? POSIX?)
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* might like the above to be functions, not macros (why?).
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* if that's true, then detect them, and take measures.
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* Anyway, the measure is: define only ___ntohl as a macro instead,
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* and in a separate file, have
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* unsigned long inline ntohl(x){return ___ntohl(x);}
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*
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* The same for constant arguments
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* __constant_ntohl(__u32 x)
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* __constant_ntohs(__u16 x)
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* __constant_htonl(__u32 x)
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* __constant_htons(__u16 x)
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*
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* Conversion of XX-bit integers (16- 32- or 64-)
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* between native CPU format and little/big endian format
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* 64-bit stuff only defined for proper architectures
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* cpu_to_[bl]eXX(__uXX x)
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* [bl]eXX_to_cpu(__uXX x)
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*
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* The same, but takes a pointer to the value to convert
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* cpu_to_[bl]eXXp(__uXX x)
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* [bl]eXX_to_cpup(__uXX x)
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*
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* The same, but change in situ
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* cpu_to_[bl]eXXs(__uXX x)
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* [bl]eXX_to_cpus(__uXX x)
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*
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* See asm-foo/byteorder.h for examples of how to provide
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* architecture-optimized versions
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*
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*/
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#if defined(__KERNEL__)
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/*
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* inside the kernel, we can use nicknames;
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* outside of it, we must avoid POSIX namespace pollution...
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*/
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#define cpu_to_le64 __cpu_to_le64
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#define le64_to_cpu __le64_to_cpu
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#define cpu_to_le32 __cpu_to_le32
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#define le32_to_cpu __le32_to_cpu
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#define cpu_to_le16 __cpu_to_le16
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#define le16_to_cpu __le16_to_cpu
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#define cpu_to_be64 __cpu_to_be64
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#define be64_to_cpu __be64_to_cpu
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#define cpu_to_be32 __cpu_to_be32
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#define be32_to_cpu __be32_to_cpu
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#define cpu_to_be16 __cpu_to_be16
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#define be16_to_cpu __be16_to_cpu
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#define cpu_to_le64p __cpu_to_le64p
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#define le64_to_cpup __le64_to_cpup
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#define cpu_to_le32p __cpu_to_le32p
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#define le32_to_cpup __le32_to_cpup
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#define cpu_to_le16p __cpu_to_le16p
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#define le16_to_cpup __le16_to_cpup
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#define cpu_to_be64p __cpu_to_be64p
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#define be64_to_cpup __be64_to_cpup
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#define cpu_to_be32p __cpu_to_be32p
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#define be32_to_cpup __be32_to_cpup
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#define cpu_to_be16p __cpu_to_be16p
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#define be16_to_cpup __be16_to_cpup
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#define cpu_to_le64s __cpu_to_le64s
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#define le64_to_cpus __le64_to_cpus
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#define cpu_to_le32s __cpu_to_le32s
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#define le32_to_cpus __le32_to_cpus
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#define cpu_to_le16s __cpu_to_le16s
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#define le16_to_cpus __le16_to_cpus
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#define cpu_to_be64s __cpu_to_be64s
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#define be64_to_cpus __be64_to_cpus
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#define cpu_to_be32s __cpu_to_be32s
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#define be32_to_cpus __be32_to_cpus
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#define cpu_to_be16s __cpu_to_be16s
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#define be16_to_cpus __be16_to_cpus
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#endif
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#if defined(__KERNEL__)
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/*
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* Handle ntohl and suches. These have various compatibility
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* issues - like we want to give the prototype even though we
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* also have a macro for them in case some strange program
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* wants to take the address of the thing or something..
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*
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* Note that these used to return a "long" in libc5, even though
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* long is often 64-bit these days.. Thus the casts.
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*
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* They have to be macros in order to do the constant folding
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* correctly - if the argument passed into a inline function
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* it is no longer constant according to gcc..
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*/
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#undef ntohl
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#undef ntohs
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#undef htonl
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#undef htons
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/*
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* Do the prototypes. Somebody might want to take the
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* address or some such sick thing..
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*/
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extern __u32 ntohl(__be32);
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extern __be32 htonl(__u32);
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extern __u16 ntohs(__be16);
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extern __be16 htons(__u16);
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#if defined(__GNUC__) && (__GNUC__ >= 2) && defined(__OPTIMIZE__)
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#define ___htonl(x) __cpu_to_be32(x)
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#define ___htons(x) __cpu_to_be16(x)
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#define ___ntohl(x) __be32_to_cpu(x)
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#define ___ntohs(x) __be16_to_cpu(x)
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#define htonl(x) ___htonl(x)
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#define ntohl(x) ___ntohl(x)
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#define htons(x) ___htons(x)
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#define ntohs(x) ___ntohs(x)
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#endif /* OPTIMIZE */
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#endif /* KERNEL */
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#endif /* _LINUX_BYTEORDER_GENERIC_H */
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