drivers/staging/vt6656/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 #if !defined(__DEVICE_H__)
  36 #include "device.h"
  37 #endif
  38 #if !defined(__TMACRO_H__)
  39 #include "tmacro.h"
  40 #endif
  41 #if !defined(__TBIT_H__)
  42 #include "tbit.h"
  43 #endif
  44 #if !defined(__TCRC_H__)
  45 #include "tcrc.h"
  46 #endif
  47 #if !defined(__TETHER_H__)
  48 #include "tether.h"
  49 #endif
  50
  51
  52
  53
  54 /*---------------------  Static Definitions -------------------------*/
  55
  56 /*---------------------  Static Classes  ----------------------------*/
  57
  58 /*---------------------  Static Variables  --------------------------*/
  59
  60 /*---------------------  Static Functions  --------------------------*/
  61
  62 /*---------------------  Export Variables  --------------------------*/
  63
  64
  65
  66 /*
  67  * Description: Caculate multicast hash value by CRC32
  68  *
  69  * Parameters:
  70  *  In:
  71  *              pbyMultiAddr    - Multicast Address
  72  *  Out:
  73  *      none
  74  *
  75  * Return Value: Hash value
  76  *
  77  */
  78 BYTE ETHbyGetHashIndexByCrc32 (PBYTE pbyMultiAddr)
  79 {
  80     int     ii;
  81     BYTE    byTmpHash;
  82     BYTE    byHash = 0;
  83
  84     // get the least 6-bits from CRC generator
  85     byTmpHash = (BYTE)(CRCdwCrc32(pbyMultiAddr, U_ETHER_ADDR_LEN,
  86             0xFFFFFFFFL) & 0x3F);
  87     // reverse most bit to least bit
  88     for (ii = 0; ii < (sizeof(byTmpHash) * 8); ii++) {
  89         byHash <<= 1;
  90         if (BITbIsBitOn(byTmpHash, 0x01))
  91             byHash |= 1;
  92         byTmpHash >>= 1;
  93     }
  94
  95     // adjust 6-bits to the right most
  96     return (byHash >> 2);
  97 }
  98
  99
 100 /*
 101  * Description: Check CRC value of the buffer if Ok or not
 102  *
 103  * Parameters:
 104  *  In:
 105  *              pbyBuffer           - pointer of buffer (normally is rx buffer)
 106  *              cbFrameLength   - length of buffer, including CRC portion
 107  *  Out:
 108  *      none
 109  *
 110  * Return Value: TRUE if ok; FALSE if error.
 111  *
 112  */
 113 BOOL ETHbIsBufferCrc32Ok (PBYTE pbyBuffer, UINT cbFrameLength)
 114 {
 115     DWORD dwCRC;
 116
 117     dwCRC = CRCdwGetCrc32(pbyBuffer, cbFrameLength - 4);
 118     if (cpu_to_le32(*((PDWORD)(pbyBuffer + cbFrameLength - 4))) != dwCRC) {
 119         return FALSE;
 120     }
 121     return TRUE;
 122 }
 123