MP_PREC
size += (MP_PREC * 2) - (size % MP_PREC);
a->dp = allocate(1, sizeof(*a->dp) * MP_PREC);
memset(a->dp, 0x0, MP_PREC * sizeof(*a->dp));
a->alloc = MP_PREC;
size += (MP_PREC * 2) - (size % MP_PREC);