X-Git-Url: http://www.aleph1.co.uk/gitweb/?p=yaffs2.git;a=blobdiff_plain;f=yaffs_ecc.c;h=9294107c150d261bbb6c90c8c78b6590ba4b97a4;hp=0ea0305e5ceb10025f9e4016c439930631ac9a79;hb=18a85b88ac3ad344bbc8f2530c84e2a621d901c4;hpb=3ecea787c3d99a5e13bf3b826dd3ad772fbad810

diff --git a/yaffs_ecc.c b/yaffs_ecc.c
index 0ea0305..9294107 100644
--- a/yaffs_ecc.c
+++ b/yaffs_ecc.c
@@ -1,7 +1,7 @@
 /*
  * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
  *
- * Copyright (C) 2002-2010 Aleph One Ltd.
+ * Copyright (C) 2002-2011 Aleph One Ltd.
  *   for Toby Churchill Ltd and Brightstar Engineering
  *
  * Created by Charles Manning <charles@aleph1.co.uk>
@@ -16,22 +16,22 @@
  *
  * 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.
+ * 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.
  *
  */
 
+#include "yportenv.h"
+
+#include "yaffs_ecc.h"
+
 /* 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.
+ * Bit 0 of each entry indicates whether the entry has an odd or even parity,
+ * and therefore this bytes influence on the line parity.
  */
 
-#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,
@@ -67,35 +67,11 @@ static const unsigned char column_parity_table[] = {
 	0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
 };
 
-/* Count the bits in an unsigned char or a U32 */
-
-static int yaffs_count_bits(unsigned char x)
-{
-	int r = 0;
-	while (x) {
-		if (x & 1)
-			r++;
-		x >>= 1;
-	}
-	return r;
-}
-
-static int yaffs_count_bits32(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_ecc_cacl(const unsigned char *data, unsigned char *ecc)
+void yaffs_ecc_calc(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;
@@ -152,12 +128,6 @@ void yaffs_ecc_cacl(const unsigned char *data, unsigned char *ecc)
 		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 */
@@ -182,15 +152,6 @@ int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
 		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)
@@ -222,8 +183,7 @@ int yaffs_ecc_correct(unsigned char *data, unsigned char *read_ecc,
 		return 1;	/* Corrected the error */
 	}
 
-	if ((yaffs_count_bits(d0) +
-	     yaffs_count_bits(d1) + yaffs_count_bits(d2)) == 1) {
+	if ((hweight8(d0) + hweight8(d1) + hweight8(d2)) == 1) {
 		/* Reccoverable error in ecc */
 
 		read_ecc[0] = test_ecc[0];
@@ -246,7 +206,6 @@ void yaffs_ecc_calc_other(const unsigned char *data, unsigned n_bytes,
 			  struct yaffs_ecc_other *ecc_other)
 {
 	unsigned int i;
-
 	unsigned char col_parity = 0;
 	unsigned line_parity = 0;
 	unsigned line_parity_prime = 0;
@@ -307,9 +266,9 @@ int yaffs_ecc_correct_other(unsigned char *data, unsigned n_bytes,
 		return 1;	/* corrected */
 	}
 
-	if ((yaffs_count_bits32(delta_line) +
-	     yaffs_count_bits32(delta_line_prime) +
-	     yaffs_count_bits(delta_col)) == 1) {
+	if ((hweight32(delta_line) +
+	     hweight32(delta_line_prime) +
+	     hweight8(delta_col)) == 1) {
 		/* Reccoverable error in ecc */
 
 		*read_ecc = *test_ecc;