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  * Francois-Rene Rideau <fare@tunes.org> 19970707
   9  *    gathered all the good ideas from all asm-foo/byteorder.h into one file,
  10  *    cleaned them up.
  11  *    I hope it is compliant with non-GCC compilers.
  12  *    I decided to put __BYTEORDER_HAS_U64__ in byteorder.h,
  13  *    because I wasn't sure it would be ok to put it in types.h
  14  *    Upgraded it to 2.1.43
  15  * Francois-Rene Rideau <fare@tunes.org> 19971012
  16  *    Upgraded it to 2.1.57
  17  *    to please Linus T., replaced huge #ifdef's between little/big endian
  18  *    by nestedly #include'd files.
  19  * Francois-Rene Rideau <fare@tunes.org> 19971205
  20  *    Made it to 2.1.71; now a facelift:
  21  *    Put files under include/linux/byteorder/
  22  *    Split swab from generic support.
  23  *
  24  * TODO:
  25  *   = Regular kernel maintainers could also replace all these manual
  26  *    byteswap macros that remain, disseminated among drivers,
  27  *    after some grep or the sources...
  28  *   = Linus might want to rename all these macros and files to fit his taste,
  29  *    to fit his personal naming scheme.
  30  *   = it seems that a few drivers would also appreciate
  31  *    nybble swapping support...
  32  *   = every architecture could add their byteswap macro in asm/byteorder.h
  33  *    see how some architectures already do (i386, alpha, ppc, etc)
  34  *   = cpu_to_beXX and beXX_to_cpu might some day need to be well
  35  *    distinguished throughout the kernel. This is not the case currently,
  36  *    since little endian, big endian, and pdp endian machines needn't it.
  37  *    But this might be the case for, say, a port of Linux to 20/21 bit
  38  *    architectures (and F21 Linux addict around?).
  39  */
  40
  41 /*
  42  * The following macros are to be defined by <asm/byteorder.h>:
  43  *
  44  * Conversion of long and short int between network and host format
  45  *      ntohl(__u32 x)
  46  *      ntohs(__u16 x)
  47  *      htonl(__u32 x)
  48  *      htons(__u16 x)
  49  * It seems that some programs (which? where? or perhaps a standard? POSIX?)
  50  * might like the above to be functions, not macros (why?).
  51  * if that's true, then detect them, and take measures.
  52  * Anyway, the measure is: define only ___ntohl as a macro instead,
  53  * and in a separate file, have
  54  * unsigned long inline ntohl(x){return ___ntohl(x);}
  55  *
  56  * The same for constant arguments
  57  *      __constant_ntohl(__u32 x)
  58  *      __constant_ntohs(__u16 x)
  59  *      __constant_htonl(__u32 x)
  60  *      __constant_htons(__u16 x)
  61  *
  62  * Conversion of XX-bit integers (16- 32- or 64-)
  63  * between native CPU format and little/big endian format
  64  * 64-bit stuff only defined for proper architectures
  65  *      cpu_to_[bl]eXX(__uXX x)
  66  *      [bl]eXX_to_cpu(__uXX x)
  67  *
  68  * The same, but takes a pointer to the value to convert
  69  *      cpu_to_[bl]eXXp(__uXX x)
  70  *      [bl]eXX_to_cpup(__uXX x)
  71  *
  72  * The same, but change in situ
  73  *      cpu_to_[bl]eXXs(__uXX x)
  74  *      [bl]eXX_to_cpus(__uXX x)
  75  *
  76  * See asm-foo/byteorder.h for examples of how to provide
  77  * architecture-optimized versions
  78  *
  79  */
  80
  81
  82 #if defined(__KERNEL__)
  83 /*
  84  * inside the kernel, we can use nicknames;
  85  * outside of it, we must avoid POSIX namespace pollution...
  86  */
  87 #define cpu_to_le64 __cpu_to_le64
  88 #define le64_to_cpu __le64_to_cpu
  89 #define cpu_to_le32 __cpu_to_le32
  90 #define le32_to_cpu __le32_to_cpu
  91 #define cpu_to_le16 __cpu_to_le16
  92 #define le16_to_cpu __le16_to_cpu
  93 #define cpu_to_be64 __cpu_to_be64
  94 #define be64_to_cpu __be64_to_cpu
  95 #define cpu_to_be32 __cpu_to_be32
  96 #define be32_to_cpu __be32_to_cpu
  97 #define cpu_to_be16 __cpu_to_be16
  98 #define be16_to_cpu __be16_to_cpu
  99 #define cpu_to_le64p __cpu_to_le64p
 100 #define le64_to_cpup __le64_to_cpup
 101 #define cpu_to_le32p __cpu_to_le32p
 102 #define le32_to_cpup __le32_to_cpup
 103 #define cpu_to_le16p __cpu_to_le16p
 104 #define le16_to_cpup __le16_to_cpup
 105 #define cpu_to_be64p __cpu_to_be64p
 106 #define be64_to_cpup __be64_to_cpup
 107 #define cpu_to_be32p __cpu_to_be32p
 108 #define be32_to_cpup __be32_to_cpup
 109 #define cpu_to_be16p __cpu_to_be16p
 110 #define be16_to_cpup __be16_to_cpup
 111 #define cpu_to_le64s __cpu_to_le64s
 112 #define le64_to_cpus __le64_to_cpus
 113 #define cpu_to_le32s __cpu_to_le32s
 114 #define le32_to_cpus __le32_to_cpus
 115 #define cpu_to_le16s __cpu_to_le16s
 116 #define le16_to_cpus __le16_to_cpus
 117 #define cpu_to_be64s __cpu_to_be64s
 118 #define be64_to_cpus __be64_to_cpus
 119 #define cpu_to_be32s __cpu_to_be32s
 120 #define be32_to_cpus __be32_to_cpus
 121 #define cpu_to_be16s __cpu_to_be16s
 122 #define be16_to_cpus __be16_to_cpus
 123 #endif
 124
 125
 126 #if defined(__KERNEL__)
 127 /*
 128  * Handle ntohl and suches. These have various compatibility
 129  * issues - like we want to give the prototype even though we
 130  * also have a macro for them in case some strange program
 131  * wants to take the address of the thing or something..
 132  *
 133  * Note that these used to return a "long" in libc5, even though
 134  * long is often 64-bit these days.. Thus the casts.
 135  *
 136  * They have to be macros in order to do the constant folding
 137  * correctly - if the argument passed into a inline function
 138  * it is no longer constant according to gcc..
 139  */
 140
 141 #undef ntohl
 142 #undef ntohs
 143 #undef htonl
 144 #undef htons
 145
 146 /*
 147  * Do the prototypes. Somebody might want to take the
 148  * address or some such sick thing..
 149  */
 150 extern __u32                    ntohl(__be32);
 151 extern __be32                   htonl(__u32);
 152 extern __u16                    ntohs(__be16);
 153 extern __be16                   htons(__u16);
 154
 155 #if defined(__GNUC__) && (__GNUC__ >= 2) && defined(__OPTIMIZE__)
 156
 157 #define ___htonl(x) __cpu_to_be32(x)
 158 #define ___htons(x) __cpu_to_be16(x)
 159 #define ___ntohl(x) __be32_to_cpu(x)
 160 #define ___ntohs(x) __be16_to_cpu(x)
 161
 162 #define htonl(x) ___htonl(x)
 163 #define ntohl(x) ___ntohl(x)
 164 #define htons(x) ___htons(x)
 165 #define ntohs(x) ___ntohs(x)
 166
 167 #endif /* OPTIMIZE */
 168
 169 #endif /* KERNEL */
 170
 171
 172 #endif /* _LINUX_BYTEORDER_GENERIC_H */