linux/include/linux/byteorder/generic.h
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   1#ifndef _LINUX_BYTEORDER_GENERIC_H
   2#define _LINUX_BYTEORDER_GENERIC_H
   3
   4/*
   5 * linux/byteorder_generic.h
   6 * Generic Byte-reordering support
   7 *
   8 * The "... p" macros, like le64_to_cpup, can be used with pointers
   9 * to unaligned data, but there will be a performance penalty on 
  10 * some architectures.  Use get_unaligned for unaligned data.
  11 *
  12 * Francois-Rene Rideau <fare@tunes.org> 19970707
  13 *    gathered all the good ideas from all asm-foo/byteorder.h into one file,
  14 *    cleaned them up.
  15 *    I hope it is compliant with non-GCC compilers.
  16 *    I decided to put __BYTEORDER_HAS_U64__ in byteorder.h,
  17 *    because I wasn't sure it would be ok to put it in types.h
  18 *    Upgraded it to 2.1.43
  19 * Francois-Rene Rideau <fare@tunes.org> 19971012
  20 *    Upgraded it to 2.1.57
  21 *    to please Linus T., replaced huge #ifdef's between little/big endian
  22 *    by nestedly #include'd files.
  23 * Francois-Rene Rideau <fare@tunes.org> 19971205
  24 *    Made it to 2.1.71; now a facelift:
  25 *    Put files under include/linux/byteorder/
  26 *    Split swab from generic support.
  27 *
  28 * TODO:
  29 *   = Regular kernel maintainers could also replace all these manual
  30 *    byteswap macros that remain, disseminated among drivers,
  31 *    after some grep or the sources...
  32 *   = Linus might want to rename all these macros and files to fit his taste,
  33 *    to fit his personal naming scheme.
  34 *   = it seems that a few drivers would also appreciate
  35 *    nybble swapping support...
  36 *   = every architecture could add their byteswap macro in asm/byteorder.h
  37 *    see how some architectures already do (i386, alpha, ppc, etc)
  38 *   = cpu_to_beXX and beXX_to_cpu might some day need to be well
  39 *    distinguished throughout the kernel. This is not the case currently,
  40 *    since little endian, big endian, and pdp endian machines needn't it.
  41 *    But this might be the case for, say, a port of Linux to 20/21 bit
  42 *    architectures (and F21 Linux addict around?).
  43 */
  44
  45/*
  46 * The following macros are to be defined by <asm/byteorder.h>:
  47 *
  48 * Conversion of long and short int between network and host format
  49 *      ntohl(__u32 x)
  50 *      ntohs(__u16 x)
  51 *      htonl(__u32 x)
  52 *      htons(__u16 x)
  53 * It seems that some programs (which? where? or perhaps a standard? POSIX?)
  54 * might like the above to be functions, not macros (why?).
  55 * if that's true, then detect them, and take measures.
  56 * Anyway, the measure is: define only ___ntohl as a macro instead,
  57 * and in a separate file, have
  58 * unsigned long inline ntohl(x){return ___ntohl(x);}
  59 *
  60 * The same for constant arguments
  61 *      __constant_ntohl(__u32 x)
  62 *      __constant_ntohs(__u16 x)
  63 *      __constant_htonl(__u32 x)
  64 *      __constant_htons(__u16 x)
  65 *
  66 * Conversion of XX-bit integers (16- 32- or 64-)
  67 * between native CPU format and little/big endian format
  68 * 64-bit stuff only defined for proper architectures
  69 *      cpu_to_[bl]eXX(__uXX x)
  70 *      [bl]eXX_to_cpu(__uXX x)
  71 *
  72 * The same, but takes a pointer to the value to convert
  73 *      cpu_to_[bl]eXXp(__uXX x)
  74 *      [bl]eXX_to_cpup(__uXX x)
  75 *
  76 * The same, but change in situ
  77 *      cpu_to_[bl]eXXs(__uXX x)
  78 *      [bl]eXX_to_cpus(__uXX x)
  79 *
  80 * See asm-foo/byteorder.h for examples of how to provide
  81 * architecture-optimized versions
  82 *
  83 */
  84
  85
  86#if defined(__KERNEL__)
  87/*
  88 * inside the kernel, we can use nicknames;
  89 * outside of it, we must avoid POSIX namespace pollution...
  90 */
  91#define cpu_to_le64 __cpu_to_le64
  92#define le64_to_cpu __le64_to_cpu
  93#define cpu_to_le32 __cpu_to_le32
  94#define le32_to_cpu __le32_to_cpu
  95#define cpu_to_le16 __cpu_to_le16
  96#define le16_to_cpu __le16_to_cpu
  97#define cpu_to_be64 __cpu_to_be64
  98#define be64_to_cpu __be64_to_cpu
  99#define cpu_to_be32 __cpu_to_be32
 100#define be32_to_cpu __be32_to_cpu
 101#define cpu_to_be16 __cpu_to_be16
 102#define be16_to_cpu __be16_to_cpu
 103#define cpu_to_le64p __cpu_to_le64p
 104#define le64_to_cpup __le64_to_cpup
 105#define cpu_to_le32p __cpu_to_le32p
 106#define le32_to_cpup __le32_to_cpup
 107#define cpu_to_le16p __cpu_to_le16p
 108#define le16_to_cpup __le16_to_cpup
 109#define cpu_to_be64p __cpu_to_be64p
 110#define be64_to_cpup __be64_to_cpup
 111#define cpu_to_be32p __cpu_to_be32p
 112#define be32_to_cpup __be32_to_cpup
 113#define cpu_to_be16p __cpu_to_be16p
 114#define be16_to_cpup __be16_to_cpup
 115#define cpu_to_le64s __cpu_to_le64s
 116#define le64_to_cpus __le64_to_cpus
 117#define cpu_to_le32s __cpu_to_le32s
 118#define le32_to_cpus __le32_to_cpus
 119#define cpu_to_le16s __cpu_to_le16s
 120#define le16_to_cpus __le16_to_cpus
 121#define cpu_to_be64s __cpu_to_be64s
 122#define be64_to_cpus __be64_to_cpus
 123#define cpu_to_be32s __cpu_to_be32s
 124#define be32_to_cpus __be32_to_cpus
 125#define cpu_to_be16s __cpu_to_be16s
 126#define be16_to_cpus __be16_to_cpus
 127
 128/*
 129 * They have to be macros in order to do the constant folding
 130 * correctly - if the argument passed into a inline function
 131 * it is no longer constant according to gcc..
 132 */
 133
 134#undef ntohl
 135#undef ntohs
 136#undef htonl
 137#undef htons
 138
 139#define ___htonl(x) __cpu_to_be32(x)
 140#define ___htons(x) __cpu_to_be16(x)
 141#define ___ntohl(x) __be32_to_cpu(x)
 142#define ___ntohs(x) __be16_to_cpu(x)
 143
 144#define htonl(x) ___htonl(x)
 145#define ntohl(x) ___ntohl(x)
 146#define htons(x) ___htons(x)
 147#define ntohs(x) ___ntohs(x)
 148
 149#endif /* KERNEL */
 150
 151#endif /* _LINUX_BYTEORDER_GENERIC_H */
 152