1 /*
2 * Copyright (c) 2003 VIA Networking, Inc. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 *
19 * File: tether.c
20 *
21 * Purpose:
22 *
23 * Author: Tevin Chen
24 *
25 * Date: May 21, 1996
26 *
27 * Functions:
28 * ETHbyGetHashIndexByCrc32 - Calculate multicast hash value by CRC32
29 * ETHbIsBufferCrc32Ok - Check CRC value of the buffer if Ok or not
30 *
31 * Revision History:
32 *
33 */
34
35 #include "device.h"
36 #include "tmacro.h"
37 #include "tcrc.h"
38 #include "tether.h"
39
40 /*--------------------- Static Definitions -------------------------*/
41
42 /*--------------------- Static Classes ----------------------------*/
43
44 /*--------------------- Static Variables --------------------------*/
45
46 /*--------------------- Static Functions --------------------------*/
47
48 /*--------------------- Export Variables --------------------------*/
49
50 /*
51 * Description: Calculate multicast hash value by CRC32
52 *
53 * Parameters:
54 * In:
55 * pbyMultiAddr - Multicast Address
56 * Out:
57 * none
58 *
59 * Return Value: Hash value
60 *
61 */
ETHbyGetHashIndexByCrc32(unsigned char * pbyMultiAddr)62 unsigned char ETHbyGetHashIndexByCrc32(unsigned char *pbyMultiAddr)
63 {
64 int ii;
65 unsigned char byTmpHash;
66 unsigned char byHash = 0;
67
68 // get the least 6-bits from CRC generator
69 byTmpHash = (unsigned char)(CRCdwCrc32(pbyMultiAddr, ETH_ALEN,
70 0xFFFFFFFFL) & 0x3F);
71 // reverse most bit to least bit
72 for (ii = 0; ii < (sizeof(byTmpHash) * 8); ii++) {
73 byHash <<= 1;
74 if (byTmpHash & 0x01)
75 byHash |= 1;
76 byTmpHash >>= 1;
77 }
78
79 // adjust 6-bits to the right most
80 return byHash >> 2;
81 }
82
83 /*
84 * Description: Check CRC value of the buffer if Ok or not
85 *
86 * Parameters:
87 * In:
88 * pbyBuffer - pointer of buffer (normally is rx buffer)
89 * cbFrameLength - length of buffer, including CRC portion
90 * Out:
91 * none
92 *
93 * Return Value: true if ok; false if error.
94 *
95 */
ETHbIsBufferCrc32Ok(unsigned char * pbyBuffer,unsigned int cbFrameLength)96 bool ETHbIsBufferCrc32Ok(unsigned char *pbyBuffer, unsigned int cbFrameLength)
97 {
98 unsigned long dwCRC;
99
100 dwCRC = CRCdwGetCrc32(pbyBuffer, cbFrameLength - 4);
101 if (cpu_to_le32(*((unsigned long *)(pbyBuffer + cbFrameLength - 4))) != dwCRC)
102 return false;
103
104 return true;
105 }
106