drivers/staging/vt6655/tether.c

   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 "tbit.h"
  38 #include "tcrc.h"
  39 #include "tether.h"
  40
  41 /*---------------------  Static Definitions -------------------------*/
  42
  43 /*---------------------  Static Classes  ----------------------------*/
  44
  45 /*---------------------  Static Variables  --------------------------*/
  46
  47 /*---------------------  Static Functions  --------------------------*/
  48
  49 /*---------------------  Export Variables  --------------------------*/
  50
  51
  52
  53 /*
  54  * Description: Caculate multicast hash value by CRC32
  55  *
  56  * Parameters:
  57  *  In:
  58  *              pbyMultiAddr    - Multicast Address
  59  *  Out:
  60  *      none
  61  *
  62  * Return Value: Hash value
  63  *
  64  */
  65 BYTE ETHbyGetHashIndexByCrc32 (PBYTE pbyMultiAddr)
  66 {
  67     int     ii;
  68     BYTE    byTmpHash;
  69     BYTE    byHash = 0;
  70
  71     // get the least 6-bits from CRC generator
  72     byTmpHash = (BYTE)(CRCdwCrc32(pbyMultiAddr, U_ETHER_ADDR_LEN,
  73             0xFFFFFFFFL) & 0x3F);
  74     // reverse most bit to least bit
  75     for (ii = 0; ii < (sizeof(byTmpHash) * 8); ii++) {
  76         byHash <<= 1;
  77         if (BITbIsBitOn(byTmpHash, 0x01))
  78             byHash |= 1;
  79         byTmpHash >>= 1;
  80     }
  81
  82     // adjust 6-bits to the right most
  83     return (byHash >> 2);
  84 }
  85
  86
  87 /*
  88  * Description: Check CRC value of the buffer if Ok or not
  89  *
  90  * Parameters:
  91  *  In:
  92  *              pbyBuffer           - pointer of buffer (normally is rx buffer)
  93  *              cbFrameLength   - length of buffer, including CRC portion
  94  *  Out:
  95  *      none
  96  *
  97  * Return Value: TRUE if ok; FALSE if error.
  98  *
  99  */
 100 BOOL ETHbIsBufferCrc32Ok (PBYTE pbyBuffer, UINT cbFrameLength)
 101 {
 102     DWORD dwCRC;
 103
 104     dwCRC = CRCdwGetCrc32(pbyBuffer, cbFrameLength - 4);
 105     if (cpu_to_le32(*((PDWORD)(pbyBuffer + cbFrameLength - 4))) != dwCRC) {
 106         return FALSE;
 107     }
 108     return TRUE;
 109 }
 110