XHCI_MFINDEX_GET
y = XHCI_MFINDEX_GET(x - xfer->endpoint->isoc_next);
(XHCI_MFINDEX_GET(-y) >= (128 * 8))) {
xfer->endpoint->isoc_next = XHCI_MFINDEX_GET(x + (3 * 8));
y = XHCI_MFINDEX_GET(xfer->endpoint->isoc_next - (x & ~7));