ref: 7975eec3e602fd5bc3e93c78f4166259190f2fe9
dir: /libnandfs/correctauxilliary.c/
#include "logfsos.h" #include "logfs.h" #include "nandfs.h" #include "local.h" static int hammingdistance(uchar a, uchar b) { uchar c; int i, k; if (a == b) return 0; c = a ^ b; for (i = 0x80, k = 0; i; i >>= 1) if (c & i) k++; return k; } static int allones(uchar *data, int len) { while (len-- > 0) if (*data++ != 0xff) return 0; return 1; } LogfsLowLevelReadResult _nandfscorrectauxiliary(NandfsAuxiliary *hdr) { /* * correct single bit errors, detect more than 1, in * tag, signature * TODO: add nerase and path protection */ LogfsLowLevelReadResult e; int x; int min, minx; e = LogfsLowLevelReadResultOk; min = 8; minx = 0; for (x = 0; x < _nandfsvalidtagscount; x++) { int d = hammingdistance(hdr->tag, _nandfsvalidtags[x]); if (d < min) { min = d; minx = x; if (d == 0) break; } } if (min == 1) { hdr->tag = _nandfsvalidtags[minx]; e = LogfsLowLevelReadResultSoftError; } else if (min > 1) e = LogfsLowLevelReadResultHardError; else { if (hdr->tag != LogfsTnone) { ulong tmp = getbig4(hdr->parth); if (tmp != 0xffffffff && _nandfshamming31_26correct(&tmp)) { putbig4(hdr->parth, tmp); if (e != LogfsLowLevelReadResultOk) e = LogfsLowLevelReadResultSoftError; } tmp = (getbig2(hdr->nerasemagicmsw) << 16) | getbig2(hdr->nerasemagiclsw); if (tmp != 0xffffffff && _nandfshamming31_26correct(&tmp)) { putbig2(hdr->nerasemagicmsw, tmp >> 16); putbig2(hdr->nerasemagiclsw, tmp); if (e != LogfsLowLevelReadResultOk) e = LogfsLowLevelReadResultSoftError; } } else if (allones((uchar *)hdr, sizeof(*hdr))) e = LogfsLowLevelReadResultAllOnes; } return e; }