1/* Macros to swap the order of bytes in integer values.
2   Copyright (C) 1997, 1998, 2000, 2002, 2003 Free Software Foundation, Inc.
3   This file is part of the GNU C Library.
4
5   The GNU C Library is free software; you can redistribute it and/or
6   modify it under the terms of the GNU Lesser General Public
7   License as published by the Free Software Foundation; either
8   version 2.1 of the License, or (at your option) any later version.
9
10   The GNU C Library is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   Lesser General Public License for more details.
14
15   You should have received a copy of the GNU Lesser General Public
16   License along with the GNU C Library; if not, write to the Free
17   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18   02111-1307 USA.  */
19
20#if !defined _BYTESWAP_H && !defined _NETINET_IN_H
21# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
22#endif
23
24#ifndef _BITS_BYTESWAP_H
25#define _BITS_BYTESWAP_H 1
26
27#include <bits/wordsize.h>
28
29/* Swap bytes in 16 bit value.  */
30#define __bswap_constant_16(x) \
31     ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))
32
33#if defined __GNUC__ && __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
52
53/* Swap bytes in 32 bit value.  */
54#define __bswap_constant_32(x) \
55     ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |		      \
56      (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
57
58#if defined __GNUC__ && __GNUC__ >= 2
59# if __WORDSIZE == 64 || (defined __i486__ || defined __pentium__	      \
60			  || defined __pentiumpro__ || defined __pentium4__   \
61			  || defined __k8__ || defined __athlon__	      \
62			  || defined __k6__)
63/* To swap the bytes in a word the i486 processors and up provide the
64   `bswap' opcode.  On i386 we have to use three instructions.  */
65#  define __bswap_32(x) \
66     (__extension__							      \
67      ({ register unsigned int __v, __x = (x);				      \
68	 if (__builtin_constant_p (__x))				      \
69	   __v = __bswap_constant_32 (__x);				      \
70	 else								      \
71	   __asm__ ("bswap %0" : "=r" (__v) : "0" (__x));		      \
72	 __v; }))
73# else
74#  define __bswap_32(x)							      \
75     (__extension__							      \
76      ({ register unsigned int __v, __x = (x);				      \
77	 if (__builtin_constant_p (__x))				      \
78	   __v = __bswap_constant_32 (__x);				      \
79	 else								      \
80	   __asm__ ("rorw $8, %w0;"					      \
81		    "rorl $16, %0;"					      \
82		    "rorw $8, %w0"					      \
83		    : "=r" (__v)					      \
84		    : "0" (__x)						      \
85		    : "cc");						      \
86	 __v; }))
87# endif
88#else
89# define __bswap_32(x) \
90     (__extension__							      \
91      ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
92#endif
93
94
95#if defined __GNUC__ && __GNUC__ >= 2
96/* Swap bytes in 64 bit value.  */
97# define __bswap_constant_64(x) \
98     ((((x) & 0xff00000000000000ull) >> 56)				      \
99      | (((x) & 0x00ff000000000000ull) >> 40)				      \
100      | (((x) & 0x0000ff0000000000ull) >> 24)				      \
101      | (((x) & 0x000000ff00000000ull) >> 8)				      \
102      | (((x) & 0x00000000ff000000ull) << 8)				      \
103      | (((x) & 0x0000000000ff0000ull) << 24)				      \
104      | (((x) & 0x000000000000ff00ull) << 40)				      \
105      | (((x) & 0x00000000000000ffull) << 56))
106
107# if __WORDSIZE == 64
108#  define __bswap_64(x) \
109     (__extension__							      \
110      ({ register unsigned long __v, __x = (x);				      \
111	 if (__builtin_constant_p (__x))				      \
112	   __v = __bswap_constant_64 (__x);				      \
113	 else								      \
114	   __asm__ ("bswap %q0" : "=r" (__v) : "0" (__x));		      \
115	 __v; }))
116# else
117#  define __bswap_64(x) \
118     (__extension__                                                           \
119      ({ union { __extension__ unsigned long long int __ll;                   \
120                 unsigned int __l[2]; } __w, __r;                             \
121         if (__builtin_constant_p (x))                                        \
122           __r.__ll = __bswap_constant_64 (x);                                \
123         else                                                                 \
124           {                                                                  \
125             __w.__ll = (x);                                                  \
126             __r.__l[0] = __bswap_32 (__w.__l[1]);                            \
127             __r.__l[1] = __bswap_32 (__w.__l[0]);                            \
128           }                                                                  \
129         __r.__ll; }))
130# endif
131#endif
132
133#endif /* _BITS_BYTESWAP_H */
134