/*
- * YAFFS: Yet another FFS. A NAND-flash specific file system.
+ * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
*
- * yaffs_ecc.c: ECC generation/correction algorithms.
- *
- * Copyright (C) 2002 Aleph One Ltd.
+ * 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 Lesser General Public License
- * version 2.1 as published by the Free Software Foundation.
+ * 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 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
+ * 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.
+/* 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 1.2 2005-03-16 04:00:36 charles Exp $";
+const char *yaffs_ecc_c_version =
+ "$Id: yaffs_ecc.c,v 1.11 2009-03-06 17:20:50 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,
+ 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++;
+ while (x) {
+ if (x & 1)
+ r++;
x >>= 1;
}
return r;
}
-static int yaffs_CountBits32(unsigned x)
+static int yaffs_CountBits32(unsigned x)
{
int r = 0;
- while(x)
- {
- if(x & 1) r++;
+ while (x) {
+ if (x & 1)
+ r++;
x >>= 1;
}
return r;
}
-
-void yaffs_ECCCalculate(const unsigned char *data,unsigned char *ecc)
+/* 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++)
- {
+
+ for (i = 0; i < 256; i++) {
b = column_parity_table[*data++];
col_parity ^= b;
- if(b & 0x01) // odd number of bits in the byte
- {
+ 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;
+ 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;
+ 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
+ /* Swap the bytes into the wrong order */
t = ecc[0];
ecc[0] = ecc[1];
ecc[1] = t;
-#endif
+#endif
}
-int yaffs_ECCCorrect(unsigned char *data, unsigned char *read_ecc, const unsigned char *test_ecc)
+
+/* 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
+ 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)
- {
- // no error
- return 0;
- }
-
- if( ((d0 ^ (d0 >> 1)) & 0x55) == 0x55 &&
+
+ 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
+ ((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
+ /* 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;
+
+ 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;
+
+ return 1; /* Corrected the error */
}
-
- if((yaffs_CountBits(d0)+yaffs_CountBits(d1)+yaffs_CountBits(d2)) == 1)
- {
- // Reccoverable error in ecc
-
+
+ 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;
+
+ return 1; /* Corrected the error */
}
-
- // Unrecoverable error
-
+
+ /* Unrecoverable error */
+
return -1;
-
}
-
-void yaffs_ECCCalculateOther(const unsigned char *data,unsigned nBytes, yaffs_ECCOther *eccOther)
+/*
+ * 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++)
- {
+
+ for (i = 0; i < nBytes; i++) {
b = column_parity_table[*data++];
col_parity ^= b;
- if(b & 0x01) // odd number of bits in the byte
- {
+ 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)
+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 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;
+ lDelta = read_ecc->lineParity ^ test_ecc->lineParity;
lDeltaPrime = read_ecc->lineParityPrime ^ test_ecc->lineParityPrime;
-
- if((cDelta | lDelta | lDeltaPrime) == 0)
- {
- // no error
- return 0;
- }
-
- if( lDelta == ~lDeltaPrime &&
- (((cDelta ^ (cDelta >> 1)) & 0x15) == 0x15)) // Not correct
- {
- // Single bit (recoverable) error in data
-#if 0
- unsigned byte;
- unsigned bit;
-#endif
+ if ((cDelta | lDelta | lDeltaPrime) == 0)
+ return 0; /* no error */
+
+ if (lDelta == ~lDeltaPrime &&
+ (((cDelta ^ (cDelta >> 1)) & 0x15) == 0x15)) {
+ /* Single bit (recoverable) error in data */
-#ifdef CONFIG_YAFFS_ECC_WRONG_ORDER
- // swap the bytes to correct for the wrong order
- unsigned char t;
-
-#if 0 // NCB
- t = d0;
- d0 = d1;
- d1 = t;
-#else
- t = cDelta;
- cDelta = lDelta;
- lDelta = t;
-#endif
-#endif
-
bit = 0;
- if(cDelta & 0x20) bit |= 0x04;
- if(cDelta & 0x08) bit |= 0x02;
- if(cDelta & 0x02) bit |= 0x01;
+ 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;
- }
-
- if((yaffs_CountBits32(lDelta) + yaffs_CountBits32(lDeltaPrime) + yaffs_CountBits(cDelta)) == 1)
- {
- // Reccoverable error in ecc
-
- *read_ecc = *test_ecc;
- return 1;
+
+ return 1; /* corrected */
}
-
- // Unrecoverable error
-
- return -1;
-
-}
+ 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;
+}
projects / yaffs2.git / blobdiff