1 /* 2 * YAFFS: Yet another Flash File System . A NAND-flash specific file system. 3 * 4 * Copyright (C) 2002-2011 Aleph One Ltd. 5 * for Toby Churchill Ltd and Brightstar Engineering 6 * 7 * Created by Charles Manning <charles (at) 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. 22 * Thus, two such ECC blocks are used on a 512-byte NAND page. 23 * 24 */ 25 26 #ifndef __YAFFS_ECC_H__ 27 #define __YAFFS_ECC_H__ 28 29 struct yaffs_ecc_other { 30 unsigned char col_parity; 31 unsigned line_parity; 32 unsigned line_parity_prime; 33 }; 34 35 void yaffs_ecc_calc(const unsigned char *data, unsigned char *ecc); 36 int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc, 37 const unsigned char *test_ecc); 38 39 void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes, 40 struct yaffs_ecc_other *ecc); 41 int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes, 42 struct yaffs_ecc_other *read_ecc, 43 const struct yaffs_ecc_other *test_ecc); 44 #endif 45
