SV_REG_DIGITAL_PWR
v = sv_indirect_get(sc, SV_REG_DIGITAL_PWR) &~ SV_DIGITAL_OFF;
sv_indirect_set(sc, SV_REG_DIGITAL_PWR, v);
v = sv_indirect_get(sc, SV_REG_DIGITAL_PWR) | SV_DIGITAL_OFF;
sv_indirect_set(sc, SV_REG_DIGITAL_PWR, SV_DIGITAL_OFF);