DOUTAMOUNT
if (n >= DOUTAMOUNT) {
n -= DOUTAMOUNT;
out += DOUTAMOUNT;
(u_int32_t *) p, DOUTAMOUNT >> 2);
(u_int16_t *) p, DOUTAMOUNT >> 1);
p += DOUTAMOUNT;
xfer = uimin(DOUTAMOUNT, n);