/* * Pre-calculated 256-way 1 byte column parity */static const u_char nand_ecc_precalc_table[] = {	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};/* * Creates non-inverted ECC code from line parity */static void nand_trans_result(u_char reg2, u_char reg3,	u_char *ecc_code){	u_char a, b, i, tmp1, tmp2;		/* Initialize variables */	a = b = 0x80;	tmp1 = tmp2 = 0;		/* Calculate first ECC byte */	for (i = 0; i < 4; i++) {		if (reg3 & a)		/* LP15,13,11,9 --> ecc_code[0] */			tmp1 |= b;		b >>= 1;		if (reg2 & a)		/* LP14,12,10,8 --> ecc_code[0] */			tmp1 |= b;		b >>= 1;		a >>= 1;	}		/* Calculate second ECC byte */	b = 0x80;	for (i = 0; i < 4; i++) {		if (reg3 & a)		/* LP7,5,3,1 --> ecc_code[1] */			tmp2 |= b;		b >>= 1;		if (reg2 & a)		/* LP6,4,2,0 --> ecc_code[1] */			tmp2 |= b;		b >>= 1;		a >>= 1;	}		/* Store two of the ECC bytes */	ecc_code[0] = tmp1;	ecc_code[1] = tmp2;}/* * Calculate 3 byte ECC code for 256 byte block */void nand_calculate_ecc (const u_char *dat, u_char *ecc_code){	u_char idx, reg1, reg2, reg3;	int j;		/* Initialize variables */	reg1 = reg2 = reg3 = 0;	ecc_code[0] = ecc_code[1] = ecc_code[2] = 0;		/* Build up column parity */ 	for(j = 0; j < 256; j++) {				/* Get CP0 - CP5 from table */		idx = nand_ecc_precalc_table[dat[j]];		reg1 ^= (idx & 0x3f);				/* All bit XOR = 1 ? */		if (idx & 0x40) {			reg3 ^= (u_char) j;			reg2 ^= ~((u_char) j);		}	}		/* Create non-inverted ECC code from line parity */	nand_trans_result(reg2, reg3, ecc_code);		/* Calculate final ECC code */	ecc_code[0] = ~ecc_code[0];	ecc_code[1] = ~ecc_code[1];	ecc_code[2] = ((~reg1) << 2) | 0x03;}