sisusb_getidxreg
#define GETIREG(r, i, d) sisusb_getidxreg(sisusb, r, i, d)
sisusb_getidxreg(sisusb, SISSR, 0x14, &tmp8);
sisusb_getidxreg(sisusb, SISSR, 0x15, &tmp82);
sisusb_getidxreg(sisusb, SISSR, 0x3a, &ramtype);
retval = sisusb_getidxreg(sisusb, port, y->data0, &y->data1);