mirror of
git://projects.qi-hardware.com/openwrt-xburst.git
synced 2024-12-21 07:56:47 +02:00
c5552ad039
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@21952 3c298f89-4303-0410-b956-a3cf2f4a3e73
332 lines
7.6 KiB
C
332 lines
7.6 KiB
C
/*
|
|
* YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
|
|
*
|
|
* Copyright (C) 2002-2007 Aleph One Ltd.
|
|
* for Toby Churchill Ltd and Brightstar Engineering
|
|
*
|
|
* Created by Charles Manning <charles@aleph1.co.uk>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
/*
|
|
* This code implements the ECC algorithm used in SmartMedia.
|
|
*
|
|
* The ECC comprises 22 bits of parity information and is stuffed into 3 bytes.
|
|
* The two unused bit are set to 1.
|
|
* The ECC can correct single bit errors in a 256-byte page of data. Thus, two such ECC
|
|
* blocks are used on a 512-byte NAND page.
|
|
*
|
|
*/
|
|
|
|
/* Table generated by gen-ecc.c
|
|
* Using a table means we do not have to calculate p1..p4 and p1'..p4'
|
|
* for each byte of data. These are instead provided in a table in bits7..2.
|
|
* Bit 0 of each entry indicates whether the entry has an odd or even parity, and therefore
|
|
* this bytes influence on the line parity.
|
|
*/
|
|
|
|
const char *yaffs_ecc_c_version =
|
|
"$Id: yaffs_ecc.c,v 1.9 2007-02-14 01:09:06 wookey Exp $";
|
|
|
|
#include "yportenv.h"
|
|
|
|
#include "yaffs_ecc.h"
|
|
|
|
static const unsigned char column_parity_table[] = {
|
|
0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
|
|
0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
|
|
0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
|
|
0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
|
|
0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
|
|
0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
|
|
0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
|
|
0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
|
|
0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
|
|
0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
|
|
0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
|
|
0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
|
|
0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
|
|
0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
|
|
0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
|
|
0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
|
|
0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0,
|
|
0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
|
|
0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55,
|
|
0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
|
|
0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59,
|
|
0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
|
|
0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc,
|
|
0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
|
|
0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65,
|
|
0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
|
|
0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0,
|
|
0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
|
|
0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc,
|
|
0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
|
|
0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69,
|
|
0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
|
|
};
|
|
|
|
/* Count the bits in an unsigned char or a U32 */
|
|
|
|
static int yaffs_CountBits(unsigned char x)
|
|
{
|
|
int r = 0;
|
|
while (x) {
|
|
if (x & 1)
|
|
r++;
|
|
x >>= 1;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
static int yaffs_CountBits32(unsigned x)
|
|
{
|
|
int r = 0;
|
|
while (x) {
|
|
if (x & 1)
|
|
r++;
|
|
x >>= 1;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
/* Calculate the ECC for a 256-byte block of data */
|
|
void yaffs_ECCCalculate(const unsigned char *data, unsigned char *ecc)
|
|
{
|
|
unsigned int i;
|
|
|
|
unsigned char col_parity = 0;
|
|
unsigned char line_parity = 0;
|
|
unsigned char line_parity_prime = 0;
|
|
unsigned char t;
|
|
unsigned char b;
|
|
|
|
for (i = 0; i < 256; i++) {
|
|
b = column_parity_table[*data++];
|
|
col_parity ^= b;
|
|
|
|
if (b & 0x01) // odd number of bits in the byte
|
|
{
|
|
line_parity ^= i;
|
|
line_parity_prime ^= ~i;
|
|
}
|
|
|
|
}
|
|
|
|
ecc[2] = (~col_parity) | 0x03;
|
|
|
|
t = 0;
|
|
if (line_parity & 0x80)
|
|
t |= 0x80;
|
|
if (line_parity_prime & 0x80)
|
|
t |= 0x40;
|
|
if (line_parity & 0x40)
|
|
t |= 0x20;
|
|
if (line_parity_prime & 0x40)
|
|
t |= 0x10;
|
|
if (line_parity & 0x20)
|
|
t |= 0x08;
|
|
if (line_parity_prime & 0x20)
|
|
t |= 0x04;
|
|
if (line_parity & 0x10)
|
|
t |= 0x02;
|
|
if (line_parity_prime & 0x10)
|
|
t |= 0x01;
|
|
ecc[1] = ~t;
|
|
|
|
t = 0;
|
|
if (line_parity & 0x08)
|
|
t |= 0x80;
|
|
if (line_parity_prime & 0x08)
|
|
t |= 0x40;
|
|
if (line_parity & 0x04)
|
|
t |= 0x20;
|
|
if (line_parity_prime & 0x04)
|
|
t |= 0x10;
|
|
if (line_parity & 0x02)
|
|
t |= 0x08;
|
|
if (line_parity_prime & 0x02)
|
|
t |= 0x04;
|
|
if (line_parity & 0x01)
|
|
t |= 0x02;
|
|
if (line_parity_prime & 0x01)
|
|
t |= 0x01;
|
|
ecc[0] = ~t;
|
|
|
|
#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
|
|
// Swap the bytes into the wrong order
|
|
t = ecc[0];
|
|
ecc[0] = ecc[1];
|
|
ecc[1] = t;
|
|
#endif
|
|
}
|
|
|
|
|
|
/* Correct the ECC on a 256 byte block of data */
|
|
|
|
int yaffs_ECCCorrect(unsigned char *data, unsigned char *read_ecc,
|
|
const unsigned char *test_ecc)
|
|
{
|
|
unsigned char d0, d1, d2; /* deltas */
|
|
|
|
d0 = read_ecc[0] ^ test_ecc[0];
|
|
d1 = read_ecc[1] ^ test_ecc[1];
|
|
d2 = read_ecc[2] ^ test_ecc[2];
|
|
|
|
if ((d0 | d1 | d2) == 0)
|
|
return 0; /* no error */
|
|
|
|
if (((d0 ^ (d0 >> 1)) & 0x55) == 0x55 &&
|
|
((d1 ^ (d1 >> 1)) & 0x55) == 0x55 &&
|
|
((d2 ^ (d2 >> 1)) & 0x54) == 0x54) {
|
|
/* Single bit (recoverable) error in data */
|
|
|
|
unsigned byte;
|
|
unsigned bit;
|
|
|
|
#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
|
|
// swap the bytes to correct for the wrong order
|
|
unsigned char t;
|
|
|
|
t = d0;
|
|
d0 = d1;
|
|
d1 = t;
|
|
#endif
|
|
|
|
bit = byte = 0;
|
|
|
|
if (d1 & 0x80)
|
|
byte |= 0x80;
|
|
if (d1 & 0x20)
|
|
byte |= 0x40;
|
|
if (d1 & 0x08)
|
|
byte |= 0x20;
|
|
if (d1 & 0x02)
|
|
byte |= 0x10;
|
|
if (d0 & 0x80)
|
|
byte |= 0x08;
|
|
if (d0 & 0x20)
|
|
byte |= 0x04;
|
|
if (d0 & 0x08)
|
|
byte |= 0x02;
|
|
if (d0 & 0x02)
|
|
byte |= 0x01;
|
|
|
|
if (d2 & 0x80)
|
|
bit |= 0x04;
|
|
if (d2 & 0x20)
|
|
bit |= 0x02;
|
|
if (d2 & 0x08)
|
|
bit |= 0x01;
|
|
|
|
data[byte] ^= (1 << bit);
|
|
|
|
return 1; /* Corrected the error */
|
|
}
|
|
|
|
if ((yaffs_CountBits(d0) +
|
|
yaffs_CountBits(d1) +
|
|
yaffs_CountBits(d2)) == 1) {
|
|
/* Reccoverable error in ecc */
|
|
|
|
read_ecc[0] = test_ecc[0];
|
|
read_ecc[1] = test_ecc[1];
|
|
read_ecc[2] = test_ecc[2];
|
|
|
|
return 1; /* Corrected the error */
|
|
}
|
|
|
|
/* Unrecoverable error */
|
|
|
|
return -1;
|
|
|
|
}
|
|
|
|
|
|
/*
|
|
* ECCxxxOther does ECC calcs on arbitrary n bytes of data
|
|
*/
|
|
void yaffs_ECCCalculateOther(const unsigned char *data, unsigned nBytes,
|
|
yaffs_ECCOther * eccOther)
|
|
{
|
|
unsigned int i;
|
|
|
|
unsigned char col_parity = 0;
|
|
unsigned line_parity = 0;
|
|
unsigned line_parity_prime = 0;
|
|
unsigned char b;
|
|
|
|
for (i = 0; i < nBytes; i++) {
|
|
b = column_parity_table[*data++];
|
|
col_parity ^= b;
|
|
|
|
if (b & 0x01) {
|
|
/* odd number of bits in the byte */
|
|
line_parity ^= i;
|
|
line_parity_prime ^= ~i;
|
|
}
|
|
|
|
}
|
|
|
|
eccOther->colParity = (col_parity >> 2) & 0x3f;
|
|
eccOther->lineParity = line_parity;
|
|
eccOther->lineParityPrime = line_parity_prime;
|
|
}
|
|
|
|
int yaffs_ECCCorrectOther(unsigned char *data, unsigned nBytes,
|
|
yaffs_ECCOther * read_ecc,
|
|
const yaffs_ECCOther * test_ecc)
|
|
{
|
|
unsigned char cDelta; /* column parity delta */
|
|
unsigned lDelta; /* line parity delta */
|
|
unsigned lDeltaPrime; /* line parity delta */
|
|
unsigned bit;
|
|
|
|
cDelta = read_ecc->colParity ^ test_ecc->colParity;
|
|
lDelta = read_ecc->lineParity ^ test_ecc->lineParity;
|
|
lDeltaPrime = read_ecc->lineParityPrime ^ test_ecc->lineParityPrime;
|
|
|
|
if ((cDelta | lDelta | lDeltaPrime) == 0)
|
|
return 0; /* no error */
|
|
|
|
if (lDelta == ~lDeltaPrime &&
|
|
(((cDelta ^ (cDelta >> 1)) & 0x15) == 0x15))
|
|
{
|
|
/* Single bit (recoverable) error in data */
|
|
|
|
bit = 0;
|
|
|
|
if (cDelta & 0x20)
|
|
bit |= 0x04;
|
|
if (cDelta & 0x08)
|
|
bit |= 0x02;
|
|
if (cDelta & 0x02)
|
|
bit |= 0x01;
|
|
|
|
if(lDelta >= nBytes)
|
|
return -1;
|
|
|
|
data[lDelta] ^= (1 << bit);
|
|
|
|
return 1; /* corrected */
|
|
}
|
|
|
|
if ((yaffs_CountBits32(lDelta) + yaffs_CountBits32(lDeltaPrime) +
|
|
yaffs_CountBits(cDelta)) == 1) {
|
|
/* Reccoverable error in ecc */
|
|
|
|
*read_ecc = *test_ecc;
|
|
return 1; /* corrected */
|
|
}
|
|
|
|
/* Unrecoverable error */
|
|
|
|
return -1;
|
|
|
|
}
|
|
|