SYSTEM_CTRL_DPMS_MASK
value = (value & ~SYSTEM_CTRL_DPMS_MASK) | state;
val = peek32(SYSTEM_CTRL) & ~SYSTEM_CTRL_DPMS_MASK;
unsigned int val = peek32(SYSTEM_CTRL) & ~SYSTEM_CTRL_DPMS_MASK;
val = peek32(SYSTEM_CTRL) & ~SYSTEM_CTRL_DPMS_MASK;