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 - Caculate 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
 52/*
 53 * Description: Caculate multicast hash value by CRC32
 54 *
 55 * Parameters:
 56 *  In:
 57 *		pbyMultiAddr    - Multicast Address
 58 *  Out:
 59 *      none
 60 *
 61 * Return Value: Hash value
 62 *
 63 */
 64BYTE ETHbyGetHashIndexByCrc32(PBYTE pbyMultiAddr)
 65{
 66	int     ii;
 67	BYTE    byTmpHash;
 68	BYTE    byHash = 0;
 69
 70	/* get the least 6-bits from CRC generator */
 71	byTmpHash = (BYTE)(CRCdwCrc32(pbyMultiAddr, ETH_ALEN,
 72			0xFFFFFFFFL) & 0x3F);
 73	/* reverse most bit to least bit */
 74	for (ii = 0; ii < (sizeof(byTmpHash) * 8); ii++) {
 75		byHash <<= 1;
 76		if (byTmpHash & 0x01)
 77			byHash |= 1;
 78		byTmpHash >>= 1;
 79	}
 80
 81	/* adjust 6-bits to the right most */
 82	return byHash >> 2;
 83}
 84
 85
 86/*
 87 * Description: Check CRC value of the buffer if Ok or not
 88 *
 89 * Parameters:
 90 *  In:
 91 *		pbyBuffer	    - pointer of buffer (normally is rx buffer)
 92 *		cbFrameLength	- length of buffer, including CRC portion
 93 *  Out:
 94 *      none
 95 *
 96 * Return Value: TRUE if ok; FALSE if error.
 97 *
 98 */
 99BOOL ETHbIsBufferCrc32Ok(PBYTE pbyBuffer, unsigned int cbFrameLength)
100{
101	DWORD dwCRC;
102
103	dwCRC = CRCdwGetCrc32(pbyBuffer, cbFrameLength - 4);
104	if (cpu_to_le32(*((PDWORD)(pbyBuffer + cbFrameLength - 4))) != dwCRC)
105		return FALSE;
106	return TRUE;
107}
108