REG_WRITE0
REG_WRITE0(c, GFTTY_DATA_PTR, BUS_ADDR_LO32(addr));
REG_WRITE0(c, GFTTY_DATA_PTR_HIGH, BUS_ADDR_HI32(addr));
REG_WRITE0(c, GFTTY_DATA_LEN, (uint32_t)size);
REG_WRITE0(c, GFTTY_CMD, CMD_READ_BUFFER);
#define REG_WRITE(sc, r, v) REG_WRITE0((sc)->sc_config, (r), (v))
REG_WRITE0(&gftty_cnconfig, GFTTY_PUT_CHAR, (unsigned char)ch);