GS_S_SMODE1_REG
_reg_write_8(GS_S_SMODE1_REG, smode1 | ((u_int64_t)1 << 16));
_reg_write_8(GS_S_SMODE1_REG, smode1 & ~((u_int64_t)1 << 16));
_reg_write_8(GS_S_SMODE1_REG,