DIRHASH_EMPTY
DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) {
DH_ENTRY(dh, i) = DIRHASH_EMPTY;
dh->dh_hash[i][j] = DIRHASH_EMPTY;
while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY;
for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY;
if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY)