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 */
 62unsigned 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 */
 96bool 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}