/**
* nand_bch_calculate_ecc - [NAND Interface] Calculate ECC for data block
* @mtd: MTD block structure
* @buf: input buffer with raw data
* @code: output buffer with ECC
*/
int nand_bch_calculate_ecc(struct omap_nand_info *info, const unsigned char *buf,
unsigned char *code)
{
const struct nand_chip *chip = &info->nand;
int i, blocks = 0;
unsigned char *ecc_ptr = code;
unsigned char *data = buf;
int ecc_bytes = 0;
if (chip->ecc.size == 2048)
blocks = 4;
else
blocks = 1;
ecc_bytes = chip->ecc.bytes / blocks;
for (i = 0; i < blocks; i++)
{
data = buf + i * 512;
ecc_ptr = code + i * ecc_bytes;
memset(ecc_ptr, 0, ecc_bytes);
encode_bch(info->bch, data, 512, ecc_ptr);
}
return 0;
}
/**
** compute and store the inverted ecc of an erased ecc block
**/
void prepare_ecc_mask(struct omap_nand_info *info, const unsigned int eccsize, const unsigned int eccbytes)
{
int i;
unsigned char erased_page[eccsize];
memset(erased_page, 0xff, eccsize);
info->eccmask = malloc(eccbytes);
memset(info->eccmask, 0, eccbytes);
encode_bch(info->bch, erased_page, eccsize, info->eccmask);
for (i = 0; i < eccbytes; i++)
{
info->eccmask[i] ^= 0xff;
}
}
void BCH::encode(int encoded_bits[BCH_DEFAULT_LENGTH], const _64bits orig_n)
{
assert(k == BCH_DEFAULT_K && length == BCH_DEFAULT_LENGTH);
int orig_bits[BCH_DEFAULT_K];
toBitPattern(orig_bits,orig_n,k);
encode_bch(encoded_bits,orig_bits);
for (int i = 0; i < k; i++)
encoded_bits[i + length - k] = orig_bits[i];
//printf("[x] encoded_bits: ");
//printBitArray(encoded_bits, BCH_DEFAULT_LENGTH);
//printf("\n");
}
main()
{
int i;
read_p(); /* Read m */
generate_gf(); /* Construct the Galois Field GF(2**m) */
gen_poly(); /* Compute the generator polynomial of BCH code */
/* Randomly generate DATA */
seed = 131073;
srandom(seed);
for (i = 0; i < k; i++)
data[i] = ( random() & 65536 ) >> 16;
encode_bch(); /* encode data */
/*
* recd[] are the coefficients of c(x) = x**(length-k)*data(x) + b(x)
*/
for (i = 0; i < length - k; i++)
recd[i] = bb[i];
for (i = 0; i < k; i++)
recd[i + length - k] = data[i];
printf("Code polynomial:\nc(x) = ");
for (i = 0; i < length; i++) {
printf("%1d", recd[i]);
if (i && ((i % 50) == 0))
printf("\n");
}
printf("\n");
printf("Enter the number of errors:\n");
scanf("%d", &numerr); /* CHANNEL errors */
printf("Enter error locations (integers between");
printf(" 0 and %d): ", length-1);
/*
* recd[] are the coefficients of r(x) = c(x) + e(x)
*/
for (i = 0; i < numerr; i++)
scanf("%d", &errpos[i]);
if (numerr)
for (i = 0; i < numerr; i++)
recd[errpos[i]] ^= 1;
printf("r(x) = ");
for (i = 0; i < length; i++) {
printf("%1d", recd[i]);
if (i && ((i % 50) == 0))
printf("\n");
}
printf("\n");
decode_bch(); /* DECODE received codeword recv[] */
/*
* print out original and decoded data
*/
printf("Results:\n");
printf("original data = ");
for (i = 0; i < k; i++) {
printf("%1d", data[i]);
if (i && ((i % 50) == 0))
printf("\n");
}
printf("\nrecovered data = ");
for (i = length - k; i < length; i++) {
printf("%1d", recd[i]);
if ((i-length+k) && (((i-length+k) % 50) == 0))
printf("\n");
}
printf("\n");
/*
* DECODING ERRORS? we compare only the data portion
*/
for (i = length - k; i < length; i++)
if (data[i - length + k] != recd[i])
decerror++;
if (decerror)
printf("There were %d decoding errors in message positions\n", decerror);
else
printf("Succesful decoding\n");
}
