GDT_CMD_OPCODE
gdt_enc16(sc->sc_cmd + GDT_CMD_OPCODE, opcode);
sc->sc_cmd[GDT_CMD_OPCODE] = GDT_FLUSH;
sc->sc_cmd[GDT_CMD_OPCODE] = GDT_WRITE;
sc->sc_cmd[GDT_CMD_OPCODE] = GDT_READ;
if (gdt_dec16(sc->sc_cmd + GDT_CMD_OPCODE) == GDT_INIT)