NPB
bpb.bpbBytesPerSec * NPB) *
bpb.bpbBytesPerSec * NPB) * bpb.bpbFATs +
x = (u_int64_t)(bpb.bpbHugeSectors - x1) * bpb.bpbBytesPerSec * NPB /
(bpb.bpbSecPerClust * bpb.bpbBytesPerSec * NPB +
bpb.bpbBytesPerSec * NPB);
x = (uint64_t)bpb.bpbBigFATsecs * bpb.bpbBytesPerSec * NPB / (fat / BPN) -