AMR_SBYTE_SET
AMR_SBYTE_SET(sc, AMR_SMBOX_0, sc->amr_mailboxphys & 0xff);
AMR_SBYTE_SET(sc, AMR_SMBOX_1, (sc->amr_mailboxphys >> 8) & 0xff);
AMR_SBYTE_SET(sc, AMR_SMBOX_2, (sc->amr_mailboxphys >> 16) & 0xff);
AMR_SBYTE_SET(sc, AMR_SMBOX_3, (sc->amr_mailboxphys >> 24) & 0xff);
AMR_SBYTE_SET(sc, AMR_SMBOX_ENABLE, AMR_SMBOX_ADDR);