X-Git-Url: http://www.aleph1.co.uk/gitweb/?p=yaffs2.git;a=blobdiff_plain;f=yaffs_ecc.c;h=d037e90a2472c39b032096dd344b5f0f86e9ce97;hp=59f3ed9cd118cffb98371b827605f282ac79b40a;hb=a48028210bd3547399ecaed7b0138d6c43a1f547;hpb=2bae4078dafc0765f55763413a53b4340986a6b7

diff --git a/yaffs_ecc.c b/yaffs_ecc.c
index 59f3ed9..d037e90 100644
--- a/yaffs_ecc.c
+++ b/yaffs_ecc.c
@@ -1,27 +1,25 @@
 /*
- * 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 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.
-  *
-  */
+/*
+ * 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'
@@ -31,7 +29,7 @@
  */
 
 const char *yaffs_ecc_c_version =
-    "$Id: yaffs_ecc.c,v 1.6 2005-08-11 02:51:49 charles Exp $";
+	"$Id: yaffs_ecc.c,v 1.11 2009-03-06 17:20:50 wookey Exp $";
 
 #include "yportenv.h"
 
@@ -111,12 +109,10 @@ void yaffs_ECCCalculate(const unsigned char *data, unsigned char *ecc)
 		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;
@@ -160,7 +156,7 @@ void yaffs_ECCCalculate(const unsigned char *data, unsigned char *ecc)
 	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;
@@ -191,7 +187,7 @@ int yaffs_ECCCorrect(unsigned char *data, unsigned char *read_ecc,
 		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;
@@ -230,8 +226,8 @@ int yaffs_ECCCorrect(unsigned char *data, unsigned char *read_ecc,
 		return 1; /* Corrected the error */
 	}
 
-	if ((yaffs_CountBits(d0) + 
-	     yaffs_CountBits(d1) + 
+	if ((yaffs_CountBits(d0) +
+	     yaffs_CountBits(d1) +
 	     yaffs_CountBits(d2)) ==  1) {
 		/* Reccoverable error in ecc */
 
@@ -241,7 +237,7 @@ int yaffs_ECCCorrect(unsigned char *data, unsigned char *read_ecc,
 
 		return 1; /* Corrected the error */
 	}
-	
+
 	/* Unrecoverable error */
 
 	return -1;
@@ -253,7 +249,7 @@ int yaffs_ECCCorrect(unsigned char *data, unsigned char *read_ecc,
  * ECCxxxOther does ECC calcs on arbitrary n bytes of data
  */
 void yaffs_ECCCalculateOther(const unsigned char *data, unsigned nBytes,
-			     yaffs_ECCOther * eccOther)
+				yaffs_ECCOther *eccOther)
 {
 	unsigned int i;
 
@@ -280,8 +276,8 @@ void yaffs_ECCCalculateOther(const unsigned char *data, unsigned nBytes,
 }
 
 int yaffs_ECCCorrectOther(unsigned char *data, unsigned nBytes,
-			  yaffs_ECCOther * read_ecc,
-			  const yaffs_ECCOther * test_ecc)
+			yaffs_ECCOther *read_ecc,
+			const yaffs_ECCOther *test_ecc)
 {
 	unsigned char cDelta;	/* column parity delta */
 	unsigned lDelta;	/* line parity delta */
@@ -295,8 +291,8 @@ int yaffs_ECCCorrectOther(unsigned char *data, unsigned nBytes,
 	if ((cDelta | lDelta | lDeltaPrime) == 0)
 		return 0; /* no error */
 
-	if (lDelta == ~lDeltaPrime && (((cDelta ^ (cDelta >> 1)) & 0x15) == 0x15))
-	{
+	if (lDelta == ~lDeltaPrime &&
+	    (((cDelta ^ (cDelta >> 1)) & 0x15) == 0x15)) {
 		/* Single bit (recoverable) error in data */
 
 		bit = 0;
@@ -308,13 +304,16 @@ int yaffs_ECCCorrectOther(unsigned char *data, unsigned nBytes,
 		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) {
+			yaffs_CountBits(cDelta)) == 1) {
 		/* Reccoverable error in ecc */
 
 		*read_ecc = *test_ecc;
@@ -324,6 +323,4 @@ int yaffs_ECCCorrectOther(unsigned char *data, unsigned nBytes,
 	/* Unrecoverable error */
 
 	return -1;
-
 }
-