target/linux/generic-2.6/files/fs/yaffs2/yaffs_ecc.h

   1 /*
   2  * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
   3  *
   4  * Copyright (C) 2002-2007 Aleph One Ltd.
   5  *   for Toby Churchill Ltd and Brightstar Engineering
   6  *
   7  * Created by Charles Manning <charles@aleph1.co.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU Lesser General Public License version 2.1 as
  11  * published by the Free Software Foundation.
  12  *
  13  * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
  14  */
  15
  16  /*
  17   * This code implements the ECC algorithm used in SmartMedia.
  18   *
  19   * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
  20   * The two unused bit are set to 1.
  21   * The ECC can correct single bit errors in a 256-byte page of data. Thus, two such ECC
  22   * blocks are used on a 512-byte NAND page.
  23   *
  24   */
  25
  26 #ifndef __YAFFS_ECC_H__
  27 #define __YAFFS_ECC_H__
  28
  29 typedef struct {
  30         unsigned char colParity;
  31         unsigned lineParity;
  32         unsigned lineParityPrime;
  33 } yaffs_ECCOther;
  34
  35 void yaffs_ECCCalculate(const unsigned char *data, unsigned char *ecc);
  36 int yaffs_ECCCorrect(unsigned char *data, unsigned char *read_ecc,
  37                      const unsigned char *test_ecc);
  38
  39 void yaffs_ECCCalculateOther(const unsigned char *data, unsigned nBytes,
  40                              yaffs_ECCOther * ecc);
  41 int yaffs_ECCCorrectOther(unsigned char *data, unsigned nBytes,
  42                           yaffs_ECCOther * read_ecc,
  43                           const yaffs_ECCOther * test_ecc);
  44 #endif