include/linux/byteorder/generic.h

   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 */