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wimax_bits.h
1/* wimax_bits.h
2 * WiMax MAC Management UL-MAP Message decoder
3 *
4 * Copyright (c) 2007 by Intel Corporation.
5 *
6 * Author: Mike Harvey <michael.harvey@intel.com>
7 *
8 * Wireshark - Network traffic analyzer
9 * By Gerald Combs <gerald@wireshark.org>
10 * Copyright 1999 Gerald Combs
11 *
12 * SPDX-License-Identifier: GPL-2.0-or-later
13 */
14
15#ifndef __wimax_bits_h__
16#define __wimax_bits_h__
17
18#include <wsutil/pint.h>
19
20/********************************************************************
21 * Functions for working with nibbles and bits
22 */
23
24/* SWAR functions */
25#define _BITS(n,hi,lo) (((n)>>(lo))&((1<<(((hi)-(lo))+1))-1))
26#define _ADD_SWAP(x,y) { (x) = (x) + (y); (y) = (x) - (y); (x) = (x) - (y); }
27#define _XOR_SWAP(x,y) { (x) ^= (y); (y) ^= (x); (x) ^= (y); }
28#define _SWAP(x,y) do { int t = (x); (x) = (y); (y) = t; } while(0)
29
30
31/********************************************************************
32 * Functions for working with nibbles
33 *
34 */
35
36#define NIBBLE_MASK 0x0F
37#define BYTE_MASK 0xFF
38
39/* extract the nibble at the given nibble address 'n' of tvbuff_t 't' */
40#define TVB_NIB_NIBBLE(n,t) \
41 (((n) & 1) \
42 ? tvb_get_uint8((t), (n)/2) & NIBBLE_MASK \
43 : (tvb_get_uint8((t), (n)/2) >> 4) & NIBBLE_MASK)
44
45/* extract the byte at the given nibble address 'n' of tvbuff_t 't' */
46#define TVB_NIB_BYTE(n,t) \
47 (n) & 1 \
48 ? (tvb_get_ntohs((t), (n)/2) >> 4) & BYTE_MASK \
49 : tvb_get_uint8((t), (n)/2)
50
51/* extract 12 bits at the given nibble address */
52#define TVB_NIB_BITS12(n,t) \
53 (TVB_NIB_NIBBLE(n+2,t) | (TVB_NIB_BYTE(n,t) << 4))
54
55/* extract the word at the given nibble address 'n' of tvbuff_t 't' */
56#define TVB_NIB_WORD(n,t) \
57 (n) & 1 \
58 ? (int)((tvb_get_ntohl((t), (n)/2) >> 12) & 0x0000FFFF) \
59 : tvb_get_ntohs((t), (n)/2)
60
61/* extract the word at the given nibble address 'n' of tvbuff_t 't' */
62#define TVB_NIB_LONG(n,t) \
63 (n) & 1 \
64 ? (tvb_get_ntohl((t), (n)/2) << 4) | ((tvb_get_uint8((t), (n)/2 + 4) >> 4) & NIBBLE_MASK) \
65 : tvb_get_ntohl((t), (n)/2)
66
67/* Only currently used with nib == 1 or 2 */
68#define TVB_NIB_NIBS(nib, t, num) \
69 ((num) == 1 ? TVB_NIB_NIBBLE(nib,t) : \
70 ((num) == 2 ? TVB_NIB_BYTE(nib,t) : \
71 ((num) == 3 ? TVB_NIB_BITS12(nib,t) : \
72 ((num) == 4 ? TVB_NIB_WORD(nib,t) : \
73 0))))
74
75/* to highlight nibfields correctly in wireshark
76 * AddItem(..., WSADDR(buf,bit), WSLEN(bit), ...) */
77
78/* determine starting byte to highlight a series of nibbles */
79#define NIB_ADDR(nib) ((nib)/2)
80/* determine number of bytes to highlight a series of nibbles */
81#define NIB_LEN(nib,len) ((1 + ((nib) &1) + (len))/2)
82
83#define NIBHI(nib,len) NIB_ADDR(nib),NIB_LEN(nib,len)
84
85/********************************************************************
86 * bitfield functions - for extracting bitfields from a buffer
87 *
88 * TODO: 64 bit functions use two 32-bit values;
89 * would be better to use 32+8 bits to avoid overrunning buffers
90 *
91 */
92
93/* find the byte-address for the bitfield */
94#define ADDR(bit) ((bit) / 8)
95#define ADDR16(bit) ((bit) / 8)
96#define ADDR32(bit) ((bit) / 8)
97
98/* find the offset (from the MSB) to the start of the bitfield */
99#define OFFSET(bit) ((bit) % 8)
100#define OFFSET16(bit) ((bit) % 8)
101#define OFFSET32(bit) ((bit) % 8)
102
103/* find the number of bits to shift right (SHIFT64 is upper dword) */
104#define SHIFT(bit,num) ( 8 - ((bit)%8) - (num))
105#define SHIFT16(bit,num) (16 - ((bit)%8) - (num))
106#define SHIFT32(bit,num) (32 - ((bit)%8) - (num))
107#define SHIFT64a(bit,num) (num - (32 - OFFSET32(bit)))
108#define SHIFT64b(bit,num) (32 - ((num) - (32 - OFFSET32(bit))))
109
110/* create a mask to mask off the bitfield */
111#define MASK8(num) (0xFF >> (8 - (num)))
112#define MASK16(num) (0xFFFF >> (16 - (num)))
113#define MASK32(num) (0xFFFFFFFF >> (32 - (num)))
114#define MASK64a(bit) (MASK32(32 - OFFSET32(bit)))
115#define MASK64b(bit,num) (MASK32(num - (32 - OFFSET32(bit))))
116
117/* note that if you have a bitfield of length 2 or more, it may cross a
118 * byte boundary so you should use TVB_BIT_BITS16 */
119
120/* extract a single bit
121 * bit ... bit address
122 * tvb ... tvbuff_t
123 */
124#define TVB_BIT_BIT(bit, tvb) \
125 (( tvb_get_uint8(tvb, ADDR(bit)) >> SHIFT(bit,1) ) & 0x1)
126
127/* extract bitfield up to 9 bits
128 * bit ... bit address
129 * tvb ... tvbuff_t
130 * num ... length of bitfield
131 */
132#define TVB_BIT_BITS16(bit, tvb, num) \
133 (( tvb_get_ntohs(tvb, ADDR16(bit)) >> SHIFT16(bit,num) ) & MASK16(num))
134
135/* extract bitfield up to 24 bits
136 * bit ... bit address
137 * tvb ... tvbuff_t
138 * num ... length of bitfield
139 */
140
141#define TVB_BIT_BITS32(bit, tvb, num) \
142 ((tvb_get_ntohl(tvb, ADDR32(bit)) >> SHIFT32(bit,num) ) & MASK32(num))
143
144/* bitfield up to 32 bits */
145#define TVB_BIT_BITS64a(bit, tvb, num) \
146 ((tvb_get_ntohl(tvb, ADDR32(bit)) & MASK64a(bit)) << SHIFT64a(bit,num))
147
148#define TVB_BIT_BITS64b(bit, tvb, num) \
149 ((tvb_get_ntohl(tvb, ADDR32(bit)+4) >> SHIFT64b(bit,num) ) & MASK64b(bit,num))
150
151#define TVB_BIT_BITS64(bit, tvb, num) \
152 ( (OFFSET32(bit)+(num)) <= 32 \
153 ? TVB_BIT_BITS32(bit,tvb,num) \
154 : TVB_BIT_BITS64a(bit,tvb,num) \
155 | TVB_BIT_BITS64b(bit,tvb,num) )
156
157#define TVB_BIT_BITS(bit, tvb, num) \
158 ((num) == 1 ? (int)TVB_BIT_BIT(bit,tvb) : \
159 ((num) <= 9 ? (int)TVB_BIT_BITS16(bit,tvb,num) : \
160 ((num) <= 24 ? (int)TVB_BIT_BITS32(bit,tvb,num) : \
161 ((num) <= 32 ? (int)TVB_BIT_BITS64(bit,tvb,num) : \
162 (int)0 ))))
163
164/* to highlight bitfields correctly in wireshark
165 * AddItem(..., WSADDR(buf,bit), WSLEN(bit), ...) */
166
167/* determine starting byte to highlight a series of nibbles */
168#define BIT_ADDR(bit) (ADDR(bit))
169/* determine number of bytes to highlight */
170#define BIT_LEN(bit,len) (1 + ((OFFSET(bit) + len - 1) / 8))
171
172#define BITHI(bit,len) BIT_ADDR(bit),BIT_LEN(bit,len)
173
174/********************************************************************
175 * padding functions - return number of nibbles/bits needed to
176 * pad to a byte boundary */
177
178#define BIT_PADDING(bit, bits) ((bit) % (bits)) ? ((bits) - ((bit) % (bits))) : 0
179#define NIB_PADDING(nib) ((nib) & 0x1)
180
181/********************************************************************
182 * conversion functions - between bytes, nibbles, and bits */
183
184#define BYTE_TO_BIT(n) ((n) * 8)
185#define BYTE_TO_NIB(n) ((n) * 2)
186
187#define BIT_TO_BYTE(n) ((n) / 8)
188#define BIT_TO_NIB(n) ((n) / 4)
189
190#define NIB_TO_BYTE(n) ((n) / 2)
191#define NIB_TO_BIT(n) ((n) * 4)
192
193#endif
194
pint.h