| xj | b04a402 | 2021-11-25 15:01:52 +0800 | [diff] [blame] | 1 | /* |
| 2 | * YAFFS: Yet another Flash File System . A NAND-flash specific file system. |
| 3 | * |
| 4 | * Copyright (C) 2002-2018 Aleph One Ltd. |
| 5 | * |
| 6 | * Created by Charles Manning <charles@aleph1.co.uk> |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU Lesser General Public License version 2.1 as |
| 10 | * published by the Free Software Foundation. |
| 11 | * |
| 12 | * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL. |
| 13 | */ |
| 14 | |
| 15 | /* |
| 16 | * This code implements the ECC algorithm used in SmartMedia. |
| 17 | * |
| 18 | * The ECC comprises 22 bits of parity information and is stuffed into 3 bytes. |
| 19 | * The two unused bit are set to 1. |
| 20 | * The ECC can correct single bit errors in a 256-byte page of data. |
| 21 | * Thus, two such ECC blocks are used on a 512-byte NAND page. |
| 22 | * |
| 23 | */ |
| 24 | |
| 25 | #ifndef __YAFFS_ECC_H__ |
| 26 | #define __YAFFS_ECC_H__ |
| 27 | |
| 28 | struct yaffs_ecc_other { |
| 29 | unsigned char col_parity; |
| 30 | unsigned line_parity; |
| 31 | unsigned line_parity_prime; |
| 32 | }; |
| 33 | |
| 34 | void yaffs_ecc_calc(const unsigned char *data, unsigned char *ecc); |
| 35 | int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc, |
| 36 | const unsigned char *test_ecc); |
| 37 | |
| 38 | void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes, |
| 39 | struct yaffs_ecc_other *ecc); |
| 40 | int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes, |
| 41 | struct yaffs_ecc_other *read_ecc, |
| 42 | const struct yaffs_ecc_other *test_ecc); |
| 43 | #endif |