xref: /freebsd/sys/i386/include/endian.h (revision 3157ba21)
1 /*-
2  * Copyright (c) 1987, 1991 Regents of the University of California.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	@(#)endian.h	7.8 (Berkeley) 4/3/91
30  * $FreeBSD$
31  */
32 
33 #ifndef _MACHINE_ENDIAN_H_
34 #define	_MACHINE_ENDIAN_H_
35 
36 #include <sys/cdefs.h>
37 #include <sys/_types.h>
38 
39 #ifdef __cplusplus
40 extern "C" {
41 #endif
42 
43 /*
44  * Define the order of 32-bit words in 64-bit words.
45  */
46 #define	_QUAD_HIGHWORD 1
47 #define	_QUAD_LOWWORD 0
48 
49 /*
50  * Definitions for byte order, according to byte significance from low
51  * address to high.
52  */
53 #define	_LITTLE_ENDIAN	1234	/* LSB first: i386, vax */
54 #define	_BIG_ENDIAN	4321	/* MSB first: 68000, ibm, net */
55 #define	_PDP_ENDIAN	3412	/* LSB first in word, MSW first in long */
56 
57 #define	_BYTE_ORDER	_LITTLE_ENDIAN
58 
59 /*
60  * Deprecated variants that don't have enough underscores to be useful in more
61  * strict namespaces.
62  */
63 #if __BSD_VISIBLE
64 #define	LITTLE_ENDIAN	_LITTLE_ENDIAN
65 #define	BIG_ENDIAN	_BIG_ENDIAN
66 #define	PDP_ENDIAN	_PDP_ENDIAN
67 #define	BYTE_ORDER	_BYTE_ORDER
68 #endif
69 
70 #if defined(__GNUCLIKE_ASM) && defined(__GNUCLIKE_BUILTIN_CONSTANT_P)
71 
72 #define __byte_swap_int_var(x) \
73 __extension__ ({ register __uint32_t __X = (x); \
74    __asm ("bswap %0" : "+r" (__X)); \
75    __X; })
76 
77 #ifdef __OPTIMIZE__
78 
79 #define	__byte_swap_int_const(x) \
80 	((((x) & 0xff000000) >> 24) | \
81 	 (((x) & 0x00ff0000) >>  8) | \
82 	 (((x) & 0x0000ff00) <<  8) | \
83 	 (((x) & 0x000000ff) << 24))
84 #define	__byte_swap_int(x) (__builtin_constant_p(x) ? \
85 	__byte_swap_int_const(x) : __byte_swap_int_var(x))
86 
87 #else	/* __OPTIMIZE__ */
88 
89 #define	__byte_swap_int(x) __byte_swap_int_var(x)
90 
91 #endif	/* __OPTIMIZE__ */
92 
93 static __inline __uint64_t
94 __bswap64(__uint64_t _x)
95 {
96 
97 	return ((_x >> 56) | ((_x >> 40) & 0xff00) | ((_x >> 24) & 0xff0000) |
98 	    ((_x >> 8) & 0xff000000) | ((_x << 8) & ((__uint64_t)0xff << 32)) |
99 	    ((_x << 24) & ((__uint64_t)0xff << 40)) |
100 	    ((_x << 40) & ((__uint64_t)0xff << 48)) | ((_x << 56)));
101 }
102 
103 static __inline __uint32_t
104 __bswap32(__uint32_t _x)
105 {
106 
107 	return (__byte_swap_int(_x));
108 }
109 
110 static __inline __uint16_t
111 __bswap16(__uint16_t _x)
112 {
113 	return (_x << 8 | _x >> 8);
114 }
115 
116 #define	__htonl(x)	__bswap32(x)
117 #define	__htons(x)	__bswap16(x)
118 #define	__ntohl(x)	__bswap32(x)
119 #define	__ntohs(x)	__bswap16(x)
120 
121 #else /* !(__GNUCLIKE_ASM && __GNUCLIKE_BUILTIN_CONSTANT_P) */
122 
123 /*
124  * No optimizations are available for this compiler.  Fall back to
125  * non-optimized functions by defining the constant usually used to prevent
126  * redefinition.
127  */
128 #define	_BYTEORDER_FUNC_DEFINED
129 
130 #endif /* __GNUCLIKE_ASM && __GNUCLIKE_BUILTIN_CONSTANT_P */
131 
132 #ifdef __cplusplus
133 }
134 #endif
135 
136 #endif /* !_MACHINE_ENDIAN_H_ */
137