BXR4
rv = BXR4(pcs, IspVirt2Off(pcs, regoff));
rv = BXR4(pcs, IspVirt2Off(pcs, regoff));
rv = BXR4(pcs, IspVirt2Off(pcs, regoff)) >> 16;
(void)BXR4(pcs, IspVirt2Off(pcs, regoff));
r2hisr = BXR4(pcs, IspVirt2Off(pcs, BIU2400_R2HSTSLO));