fdwalk should return 0 on an empty directory
[kopensolaris-gnu/glibc.git] / sysdeps / i386 / bits / byteswap.h
1 /* Macros to swap the order of bytes in integer values.
2    Copyright (C) 1997, 1998, 2000, 2002, 2003, 2006, 2007
3    Free Software Foundation, Inc.
4    This file is part of the GNU C Library.
5
6    The GNU C Library is free software; you can redistribute it and/or
7    modify it under the terms of the GNU Lesser General Public
8    License as published by the Free Software Foundation; either
9    version 2.1 of the License, or (at your option) any later version.
10
11    The GNU C Library is distributed in the hope that it will be useful,
12    but WITHOUT ANY WARRANTY; without even the implied warranty of
13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14    Lesser General Public License for more details.
15
16    You should have received a copy of the GNU Lesser General Public
17    License along with the GNU C Library; if not, write to the Free
18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19    02111-1307 USA.  */
20
21 #if !defined _BYTESWAP_H && !defined _NETINET_IN_H
22 # error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
23 #endif
24
25 #ifndef _BITS_BYTESWAP_H
26 #define _BITS_BYTESWAP_H 1
27
28 /* Swap bytes in 16 bit value.  */
29 #define __bswap_constant_16(x) \
30      ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
31
32 #ifdef __GNUC__
33 # if __GNUC__ >= 2
34 #  define __bswap_16(x) \
35      (__extension__                                                           \
36       ({ register unsigned short int __v, __x = (x);                          \
37          if (__builtin_constant_p (__x))                                      \
38            __v = __bswap_constant_16 (__x);                                   \
39          else                                                                 \
40            __asm__ ("rorw $8, %w0"                                            \
41                     : "=r" (__v)                                              \
42                     : "0" (__x)                                               \
43                     : "cc");                                                  \
44          __v; }))
45 # else
46 /* This is better than nothing.  */
47 #  define __bswap_16(x) \
48      (__extension__                                                           \
49       ({ register unsigned short int __x = (x); __bswap_constant_16 (__x); }))
50 # endif
51 #else
52 static __inline unsigned short int
53 __bswap_16 (unsigned short int __bsx)
54 {
55   return __bswap_constant_16 (__bsx);
56 }
57 #endif
58
59 /* Swap bytes in 32 bit value.  */
60 #define __bswap_constant_32(x) \
61      ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |               \
62       (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
63
64 #ifdef __GNUC__
65 # if __GNUC__ >= 2
66 /* To swap the bytes in a word the i486 processors and up provide the
67    `bswap' opcode.  On i386 we have to use three instructions.  */
68 #  if !defined __i486__ && !defined __pentium__ && !defined __pentiumpro__ \
69       && !defined __pentium4__ && !defined __k8__ && !defined __athlon__ \
70       && !defined __k6__ && !defined __nocona__ && !defined __core2__ \
71       && !defined __geode__ && !defined __amdfam10__
72 #   define __bswap_32(x)                                                      \
73      (__extension__                                                           \
74       ({ register unsigned int __v, __x = (x);                                \
75          if (__builtin_constant_p (__x))                                      \
76            __v = __bswap_constant_32 (__x);                                   \
77          else                                                                 \
78            __asm__ ("rorw $8, %w0;"                                           \
79                     "rorl $16, %0;"                                           \
80                     "rorw $8, %w0"                                            \
81                     : "=r" (__v)                                              \
82                     : "0" (__x)                                               \
83                     : "cc");                                                  \
84          __v; }))
85 #  else
86 #   define __bswap_32(x) \
87      (__extension__                                                           \
88       ({ register unsigned int __v, __x = (x);                                \
89          if (__builtin_constant_p (__x))                                      \
90            __v = __bswap_constant_32 (__x);                                   \
91          else                                                                 \
92            __asm__ ("bswap %0" : "=r" (__v) : "0" (__x));                     \
93          __v; }))
94 #  endif
95 # else
96 #  define __bswap_32(x) \
97      (__extension__                                                           \
98       ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
99 # endif
100 #else
101 static __inline unsigned int
102 __bswap_32 (unsigned int __bsx)
103 {
104   return __bswap_constant_32 (__bsx);
105 }
106 #endif
107
108
109 #if defined __GNUC__ && __GNUC__ >= 2
110 /* Swap bytes in 64 bit value.  */
111 #define __bswap_constant_64(x) \
112      ((((x) & 0xff00000000000000ull) >> 56)                                   \
113       | (((x) & 0x00ff000000000000ull) >> 40)                                 \
114       | (((x) & 0x0000ff0000000000ull) >> 24)                                 \
115       | (((x) & 0x000000ff00000000ull) >> 8)                                  \
116       | (((x) & 0x00000000ff000000ull) << 8)                                  \
117       | (((x) & 0x0000000000ff0000ull) << 24)                                 \
118       | (((x) & 0x000000000000ff00ull) << 40)                                 \
119       | (((x) & 0x00000000000000ffull) << 56))
120
121 # define __bswap_64(x) \
122      (__extension__                                                           \
123       ({ union { __extension__ unsigned long long int __ll;                   \
124                  unsigned long int __l[2]; } __w, __r;                        \
125          if (__builtin_constant_p (x))                                        \
126            __r.__ll = __bswap_constant_64 (x);                                \
127          else                                                                 \
128            {                                                                  \
129              __w.__ll = (x);                                                  \
130              __r.__l[0] = __bswap_32 (__w.__l[1]);                            \
131              __r.__l[1] = __bswap_32 (__w.__l[0]);                            \
132            }                                                                  \
133          __r.__ll; }))
134 #endif
135
136 #endif /* _BITS_BYTESWAP_H */