BITMASK
#define BITMASK(name, type, field, offset, size) \
#define BITMASK(bits) (BIT(bits) - 1)
#define BITMASK(t,b) (((unsigned)(1U << (((t)-(b)+1)))-1) << (b))
#define BITMASK(t,b) (((unsigned)(1U << (((t)-(b)+1)))-1) << (b))