ref: 51bf59e016b43f16ec91943829af30d99a886cc1
dir: /libnandfs/ecc.c/
#include "logfsos.h"
#include "nandecc.h"
static uchar ecctab[] = {
0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69, 0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc, 0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0, 0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65, 0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc, 0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59, 0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55, 0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0, 0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
0xa9, 0xfc, 0xf0, 0xa5, 0xcc, 0x99, 0x95, 0xc0, 0xc0, 0x95, 0x99, 0xcc, 0xa5, 0xf0, 0xfc, 0xa9,
0x3c, 0x69, 0x65, 0x30, 0x59, 0x0c, 0x00, 0x55, 0x55, 0x00, 0x0c, 0x59, 0x30, 0x65, 0x69, 0x3c,
0x30, 0x65, 0x69, 0x3c, 0x55, 0x00, 0x0c, 0x59, 0x59, 0x0c, 0x00, 0x55, 0x3c, 0x69, 0x65, 0x30,
0xa5, 0xf0, 0xfc, 0xa9, 0xc0, 0x95, 0x99, 0xcc, 0xcc, 0x99, 0x95, 0xc0, 0xa9, 0xfc, 0xf0, 0xa5,
0x0c, 0x59, 0x55, 0x00, 0x69, 0x3c, 0x30, 0x65, 0x65, 0x30, 0x3c, 0x69, 0x00, 0x55, 0x59, 0x0c,
0x99, 0xcc, 0xc0, 0x95, 0xfc, 0xa9, 0xa5, 0xf0, 0xf0, 0xa5, 0xa9, 0xfc, 0x95, 0xc0, 0xcc, 0x99,
0x95, 0xc0, 0xcc, 0x99, 0xf0, 0xa5, 0xa9, 0xfc, 0xfc, 0xa9, 0xa5, 0xf0, 0x99, 0xcc, 0xc0, 0x95,
0x00, 0x55, 0x59, 0x0c, 0x65, 0x30, 0x3c, 0x69, 0x69, 0x3c, 0x30, 0x65, 0x0c, 0x59, 0x55, 0x00,
};
ulong
nandecc(uchar *buf)
{
int cp, zeros, ones, im;
int lp, om;
int i;
cp = 0xff;
zeros = 0xff;
ones = 0xff;
for (i = 0; i < 256; i++) {
int tabent = ecctab[buf[i]];
cp ^= tabent;
if (tabent & 1) {
zeros ^= ~i;
ones ^= i;
}
}
lp = 0;
for (im = 0x80, om = 0x8000; im; im >>= 1, om >>= 1) {
if (ones & im)
lp |= om;
om >>= 1;
if (zeros & im)
lp |= om;
}
return (((cp & 0xff) | 3) << 16) | lp;
}
#define CORRECTABLEMASK 0x545555
NandEccError
nandecccorrect(uchar *buf, ulong calcecc, ulong *storedecc, int reportbad)
{
ulong xorecc;
ulong mask;
int k;
if (calcecc == *storedecc)
return NandEccErrorGood;
if (reportbad)
print("nandecccorrect: calculated ecc %.8lux stored ecc %.8lux\n", calcecc, *storedecc);
xorecc = calcecc ^ *storedecc;
if (((xorecc ^ (xorecc >> 1)) & CORRECTABLEMASK) == CORRECTABLEMASK) {
ulong imask;
ushort out;
ushort omask;
int line, col;
for (imask = 0x800000, omask = 0x800, out = 0; imask; imask >>= 2, omask >>= 1) {
if (xorecc & imask)
out |= omask;
}
line = out & 0xff;
col = out >> 9;
if (reportbad)
print("nandecccorrect: single bit error line %d col %d\n", line, col);
buf[line] ^= (1 << col);
*storedecc = calcecc;
return NandEccErrorOneBit;
}
for (mask = 0x800000, k = 0; mask; mask >>= 1)
if (mask & xorecc)
k++;
if (k == 1) {
if (reportbad)
print("nandecccorrect: single bit error in ecc\n");
// assume the stored ecc was wrong
*storedecc = calcecc;
return NandEccErrorOneBitInEcc;
}
if (reportbad)
print("nandecccorrect: 2 bit error\n");
return NandEccErrorBad;
}