field_valid
bool field_valid = true;
field_valid = false;
field_valid = false;
field_valid = false;
if (!field_valid) {
if (!field_valid(nic_conf1 & 0xff))
if (!field_valid(nic_conf0 >> 8))
if (!field_valid(val))
if (!field_valid(val) || !(val & BIT(7)))
unsigned short field_valid; /* (word 53)