119 lines
3.3 KiB
C
119 lines
3.3 KiB
C
/* error correcting code for nand flash */
|
|
#include "u.h"
|
|
#include "../port/lib.h"
|
|
#include "mem.h"
|
|
#include "dat.h"
|
|
#include "fns.h"
|
|
#include "io.h"
|
|
#include "../port/error.h"
|
|
#include "nandecc.h"
|
|
|
|
#define CORRECTABLEMASK 0x545555
|
|
|
|
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, lp, om, 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;
|
|
}
|
|
|
|
NandEccError
|
|
nandecccorrect(uchar *buf, ulong calcecc, ulong *storedecc, int reportbad)
|
|
{
|
|
ulong xorecc, 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, 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;
|
|
}
|