source: SVN/rincon/u-boot/cpu/ixp/npe/IxEthDBLearning.c @ 55

Last change on this file since 55 was 55, checked in by Tim Harvey, 22 months ago

rincon: added latest u-boot source

restored form server backup

Signed-off-by: Tim Harvey <tharvey@…>

File size: 4.5 KB
Line 
1/**
2 * @file IxEthDBLearning.c
3 *
4 * @par
5 * IXP400 SW Release version 2.0
6 *
7 * -- Copyright Notice --
8 *
9 * @par
10 * Copyright 2001-2005, Intel Corporation.
11 * All rights reserved.
12 *
13 * @par
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 * 3. Neither the name of the Intel Corporation nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * @par
27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
28 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 *
39 * @par
40 * -- End of Copyright Notice --
41 */
42
43#include "IxEthDB_p.h"
44
45/**
46 * @brief hashes the mac address in a mac descriptor with a XOR function
47 *
48 * @param entry pointer to a mac descriptor to be hashed
49 *
50 * This function only extracts the mac address and employs ixEthDBKeyXORHash()
51 * to do the actual hashing.
52 * Used only to add a whole entry to a hash table, as opposed to searching which
53 * takes only a key and uses the key hashing directly.
54 *
55 * @see ixEthDBKeyXORHash()
56 *
57 * @return the hash value
58 *
59 * @internal
60 */
61UINT32 ixEthDBEntryXORHash(void *entry)
62{
63    MacDescriptor *descriptor = (MacDescriptor *) entry;
64
65    return ixEthDBKeyXORHash(descriptor->macAddress);
66}
67
68/**
69 * @brief hashes a mac address
70 *
71 * @param key pointer to a 6 byte structure (typically an IxEthDBMacAddr pointer)
72 * to be hashed
73 *
74 * Given a 6 bytes MAC address, the hash used is:
75 *
76 * hash(MAC[0:5]) = MAC[0:1] ^ MAC[2:3] ^ MAC[4:5]
77 *
78 * Used by the hash table to search and remove entries based
79 * solely on their keys (mac addresses).
80 *
81 * @return the hash value
82 *
83 * @internal
84 */
85UINT32 ixEthDBKeyXORHash(void *key)
86{
87    UINT32 hashValue;
88    UINT8 *value = (UINT8 *) key;
89   
90    hashValue  = (value[5] << 8) | value[4];
91    hashValue ^= (value[3] << 8) | value[2];
92    hashValue ^= (value[1] << 8) | value[0];
93
94    return hashValue;
95}
96
97/**
98 * @brief mac descriptor match function
99 *
100 * @param reference mac address (typically an IxEthDBMacAddr pointer) structure
101 * @param entry pointer to a mac descriptor whose key (mac address) is to be
102 * matched against the reference key
103 *
104 * Used by the hash table to retrieve entries. Hashing entries can produce
105 * collisions, i.e. descriptors with different mac addresses and the same
106 * hash value, where this function is used to differentiate entries.
107 *
108 * @retval TRUE if the entry matches the reference key (equal addresses)
109 * @retval FALSE if the entry does not match the reference key
110 *
111 * @internal
112 */
113BOOL ixEthDBAddressMatch(void *reference, void *entry)
114{
115    return (ixEthDBAddressCompare(reference, ((MacDescriptor *) entry)->macAddress) == 0);
116}
117
118/**
119 * @brief compares two mac addresses
120 *
121 * @param mac1 first mac address to compare
122 * @param mac2 second mac address to compare
123 *
124 * This comparison works in a similar way to strcmp, producing similar results.
125 * Used to insert values keyed on mac addresses into binary search trees.
126 *
127 * @retval -1 if mac1 < mac2
128 * @retval 0 if ma1 == mac2
129 * @retval 1 if mac1 > mac2
130 */
131UINT32 ixEthDBAddressCompare(UINT8 *mac1, UINT8 *mac2)
132{
133    UINT32 local_index;
134
135    for (local_index = 0 ; local_index < IX_IEEE803_MAC_ADDRESS_SIZE ; local_index++)
136    {
137        if (mac1[local_index] > mac2[local_index])
138        {
139            return 1;
140        }
141        else if (mac1[local_index] < mac2[local_index])
142        {
143            return -1;
144        }
145    }
146
147    return 0;
148}
149
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