signed_asl
buf->f_bfree = signed_asl(total, asb->s_map2blk);
mapoff = signed_asl(offset, -asb->s_map2blk);
secoff = offset - signed_asl(mapoff, asb->s_map2blk);
return secoff + signed_asl(result, asb->s_map2blk);
map_addr = signed_asl(map_addr, asb->s_map2blk);