ecc-sw.c File Reference

#include "nand.h"
#include "ecc-sw.h"

Functions
int	ecc_compare_block_256b (unsigned long *ecc1, unsigned long *ecc2, unsigned char *data, unsigned long *error_offset, unsigned char *corrected_value)
	Compare two ECCs for a 256 byte block. More...
void	ecc_make_block_256b (unsigned long *ecc, unsigned char *data)
	Generate ECC for a 256 byte block. More...

Variables
static const unsigned char	ecc_parity_table []
	Pre-calculated parity table. More...

int ecc_compare_block_256b	(	unsigned long *	ecc1,
		unsigned long *	ecc2,
		unsigned char *	data,
		unsigned long *	error_offset,
		unsigned char *	corrected_value
	)

Compare two ECCs for a 256 byte block.

This function will compare two 3 byte ECC for a 256 byte data block. If an error is found the compare function will provide a fix if a single one bit error is found. Multiple errors are not possible to fix.

Parameters

ecc1	Pointer to a variable for ECC value to compare against ecc2.
ecc2	Pointer to a variable for ECC value to compare against ecc1.
data	Pointer to a 256 byte large buffer used when calculating the ecc1 and ecc2 ECC values.
error_offset	Pointer to a variable to store the byte offset of a detected single bit error.
corrected_value	Pointer to a variable to store the corrected byte if a single bit error was detected.

Returns

0 on success, an error number otherwise.

References i.

void ecc_make_block_256b	(	unsigned long *	ecc,
		unsigned char *	data
	)

Generate ECC for a 256 byte block.

This function will generate a 3 byte ECC for a 256 byte data block.

Parameters

ecc	Pointer to a variable to store the calculated ECC.
data	Pointer to a 256 byte large buffer to calculate the ECC value of.

References data, ecc_parity_table, i, and NAND_ECC_CHUNK_SIZE.

const unsigned char ecc_parity_table[]

static

Initial value:

= {
    0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f,
    0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, 0x65, 0x30, 0x33, 0x66,
    0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33,
    0x30, 0x65, 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c,
    0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, 0x03, 0x56,
    0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a,
    0x00, 0x55, 0x56, 0x03, 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65,
    0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69,
    0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03,
    0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, 0x0f, 0x5a, 0x59, 0x0c,
    0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59,
    0x5a, 0x0f, 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30,
    0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, 0x6a, 0x3f,
    0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33,
    0x69, 0x3c, 0x3f, 0x6a, 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03,
    0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f,
    0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03,
    0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, 0x69, 0x3c, 0x3f, 0x6a,
    0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f,
    0x3c, 0x69, 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59,
    0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, 0x66, 0x33,
    0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f,
    0x65, 0x30, 0x33, 0x66, 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69,
    0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65,
    0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f,
    0x0c, 0x59, 0x03, 0x56, 0x55, 0x00,
}

Pre-calculated parity table.

This table is a pre-calculation of the 256 possible parities used when calculating ECC. Each value in this table represents a 6-bit value of the column parity and a 1-bit value of the row parity.

Storage form: null [7], row parity [6], column parity [5:0]

Referenced by ecc_make_block_256b().