Move tcpdump-3.9/ to tcpdump/. No need for a versioned dir.
[dragonfly.git] / contrib / tcpdump / extract.h
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1/*
2 * Copyright (c) 1992, 1993, 1994, 1995, 1996
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 * @(#) $Header: /tcpdump/master/tcpdump/extract.h,v 1.24 2005/01/15 02:06:50 guy Exp $ (LBL)
22 */
23
24/*
25 * Macros to extract possibly-unaligned big-endian integral values.
26 */
27#ifdef LBL_ALIGN
28/*
29 * The processor doesn't natively handle unaligned loads.
30 */
31#ifdef HAVE___ATTRIBUTE__
32/*
33 * We have __attribute__; we assume that means we have __attribute__((packed)).
34 * Declare packed structures containing a u_int16_t and a u_int32_t,
35 * cast the pointer to point to one of those, and fetch through it;
36 * the GCC manual doesn't appear to explicitly say that
37 * __attribute__((packed)) causes the compiler to generate unaligned-safe
38 * code, but it apppears to do so.
39 *
40 * We do this in case the compiler can generate, for this instruction set,
41 * better code to do an unaligned load and pass stuff to "ntohs()" or
42 * "ntohl()" than the code to fetch the bytes one at a time and
43 * assemble them. (That might not be the case on a little-endian platform,
44 * where "ntohs()" and "ntohl()" might not be done inline.)
45 */
46typedef struct {
47 u_int16_t val;
48} __attribute__((packed)) unaligned_u_int16_t;
49
50typedef struct {
51 u_int32_t val;
52} __attribute__((packed)) unaligned_u_int32_t;
53
54#define EXTRACT_16BITS(p) \
55 ((u_int16_t)ntohs(((const unaligned_u_int16_t *)(p))->val))
56#define EXTRACT_32BITS(p) \
57 ((u_int32_t)ntohl(((const unaligned_u_int32_t *)(p))->val))
58#define EXTRACT_64BITS(p) \
59 ((u_int64_t)(((u_int64_t)ntohl(((const unaligned_u_int32_t *)(p) + 0)->val)) << 32 | \
60 ((u_int64_t)ntohl(((const unaligned_u_int32_t *)(p) + 1)->val)) << 0))
61
62#else /* HAVE___ATTRIBUTE__ */
63/*
64 * We don't have __attribute__, so do unaligned loads of big-endian
65 * quantities the hard way - fetch the bytes one at a time and
66 * assemble them.
67 */
68#define EXTRACT_16BITS(p) \
69 ((u_int16_t)((u_int16_t)*((const u_int8_t *)(p) + 0) << 8 | \
70 (u_int16_t)*((const u_int8_t *)(p) + 1)))
71#define EXTRACT_32BITS(p) \
72 ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 0) << 24 | \
73 (u_int32_t)*((const u_int8_t *)(p) + 1) << 16 | \
74 (u_int32_t)*((const u_int8_t *)(p) + 2) << 8 | \
75 (u_int32_t)*((const u_int8_t *)(p) + 3)))
76#define EXTRACT_64BITS(p) \
77 ((u_int64_t)((u_int64_t)*((const u_int8_t *)(p) + 0) << 56 | \
78 (u_int64_t)*((const u_int8_t *)(p) + 1) << 48 | \
79 (u_int64_t)*((const u_int8_t *)(p) + 2) << 40 | \
80 (u_int64_t)*((const u_int8_t *)(p) + 3) << 32 | \
81 (u_int64_t)*((const u_int8_t *)(p) + 4) << 24 | \
82 (u_int64_t)*((const u_int8_t *)(p) + 5) << 16 | \
83 (u_int64_t)*((const u_int8_t *)(p) + 6) << 8 | \
84 (u_int64_t)*((const u_int8_t *)(p) + 7)))
85#endif /* HAVE___ATTRIBUTE__ */
86#else /* LBL_ALIGN */
87/*
88 * The processor natively handles unaligned loads, so we can just
89 * cast the pointer and fetch through it.
90 */
91#define EXTRACT_16BITS(p) \
92 ((u_int16_t)ntohs(*(const u_int16_t *)(p)))
93#define EXTRACT_32BITS(p) \
94 ((u_int32_t)ntohl(*(const u_int32_t *)(p)))
95#define EXTRACT_64BITS(p) \
96 ((u_int64_t)(((u_int64_t)ntohl(*((const u_int32_t *)(p) + 0))) << 32 | \
97 ((u_int64_t)ntohl(*((const u_int32_t *)(p) + 1))) << 0))
98#endif /* LBL_ALIGN */
99
100#define EXTRACT_24BITS(p) \
101 ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 0) << 16 | \
102 (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \
103 (u_int32_t)*((const u_int8_t *)(p) + 2)))
104
105/*
106 * Macros to extract possibly-unaligned little-endian integral values.
107 * XXX - do loads on little-endian machines that support unaligned loads?
108 */
109#define EXTRACT_LE_8BITS(p) (*(p))
110#define EXTRACT_LE_16BITS(p) \
111 ((u_int16_t)((u_int16_t)*((const u_int8_t *)(p) + 1) << 8 | \
112 (u_int16_t)*((const u_int8_t *)(p) + 0)))
113#define EXTRACT_LE_32BITS(p) \
114 ((u_int32_t)((u_int32_t)*((const u_int8_t *)(p) + 3) << 24 | \
115 (u_int32_t)*((const u_int8_t *)(p) + 2) << 16 | \
116 (u_int32_t)*((const u_int8_t *)(p) + 1) << 8 | \
117 (u_int32_t)*((const u_int8_t *)(p) + 0)))
118#define EXTRACT_LE_64BITS(p) \
119 ((u_int64_t)((u_int64_t)*((const u_int8_t *)(p) + 7) << 56 | \
120 (u_int64_t)*((const u_int8_t *)(p) + 6) << 48 | \
121 (u_int64_t)*((const u_int8_t *)(p) + 5) << 40 | \
122 (u_int64_t)*((const u_int8_t *)(p) + 4) << 32 | \
123 (u_int64_t)*((const u_int8_t *)(p) + 3) << 24 | \
124 (u_int64_t)*((const u_int8_t *)(p) + 2) << 16 | \
125 (u_int64_t)*((const u_int8_t *)(p) + 1) << 8 | \
126 (u_int64_t)*((const u_int8_t *)(p) + 0)))