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glibc  2.9
byteswap.h
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00001 /* Macros to swap the order of bytes in integer values.
00002    Copyright (C) 1997,1998,2000-2002,2005,2008 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public
00007    License as published by the Free Software Foundation; either
00008    version 2.1 of the License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; if not, write to the Free
00017    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00018    02111-1307 USA.  */
00019 
00020 #if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H
00021 # error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
00022 #endif
00023 
00024 #ifndef _BITS_BYTESWAP_H
00025 #define _BITS_BYTESWAP_H 1
00026 
00027 /* Swap bytes in 16 bit value.  */
00028 #define __bswap_constant_16(x) \
00029      ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
00030 
00031 #ifdef __GNUC__
00032 # define __bswap_16(x) \
00033     (__extension__                                                   \
00034      ({ unsigned short int __bsx = (x); __bswap_constant_16 (__bsx); }))
00035 #else
00036 static __inline unsigned short int
00037 __bswap_16 (unsigned short int __bsx)
00038 {
00039   return __bswap_constant_16 (__bsx);
00040 }
00041 #endif
00042 
00043 /* Swap bytes in 32 bit value.  */
00044 #define __bswap_constant_32(x) \
00045      ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >>  8) |           \
00046       (((x) & 0x0000ff00u) <<  8) | (((x) & 0x000000ffu) << 24))
00047 
00048 #ifdef __GNUC__
00049 # define __bswap_32(x) \
00050   (__extension__                                                     \
00051    ({ register unsigned int __bsx = (x); __bswap_constant_32 (__bsx); }))
00052 #else
00053 static __inline unsigned int
00054 __bswap_32 (unsigned int __bsx)
00055 {
00056   return __bswap_constant_32 (__bsx);
00057 }
00058 #endif
00059 
00060 #if defined __GNUC__ && __GNUC__ >= 2
00061 /* Swap bytes in 64 bit value.  */
00062 # define __bswap_constant_64(x) \
00063      ((((x) & 0xff00000000000000ull) >> 56)                                 \
00064       | (((x) & 0x00ff000000000000ull) >> 40)                               \
00065       | (((x) & 0x0000ff0000000000ull) >> 24)                               \
00066       | (((x) & 0x000000ff00000000ull) >> 8)                                \
00067       | (((x) & 0x00000000ff000000ull) << 8)                                \
00068       | (((x) & 0x0000000000ff0000ull) << 24)                               \
00069       | (((x) & 0x000000000000ff00ull) << 40)                               \
00070       | (((x) & 0x00000000000000ffull) << 56))
00071 
00072 # define __bswap_64(x) \
00073      (__extension__                                                  \
00074       ({ union { __extension__ unsigned long long int __ll;                 \
00075                unsigned int __l[2]; } __w, __r;                      \
00076          if (__builtin_constant_p (x))                                      \
00077           __r.__ll = __bswap_constant_64 (x);                               \
00078         else                                                         \
00079           {                                                          \
00080             __w.__ll = (x);                                          \
00081             __r.__l[0] = __bswap_32 (__w.__l[1]);                           \
00082             __r.__l[1] = __bswap_32 (__w.__l[0]);                           \
00083           }                                                          \
00084         __r.__ll; }))
00085 #endif
00086 
00087 #endif /* _BITS_BYTESWAP_H */