DISKBUFSIZE
if (tsize > DISKBUFSIZE)
tsize = DISKBUFSIZE;
maxsecs = DISKBUFSIZE / d->secsize;
maxsecs = DISKBUFSIZE / d->secsize;
diskbufp = alloc(DISKBUFSIZE);
if (((uintptr_t)diskbufp & 0xffff) + DISKBUFSIZE > 0x10000) {
#ifndef DISKBUFSIZE