FC_FCTL_ACK_SHIFT
#define FC_FCTL_ACK_NONE (0x0 << FC_FCTL_ACK_SHIFT)
#define FC_FCTL_ACK_1 (0x1 << FC_FCTL_ACK_SHIFT)
#define FC_FCTL_ACK_0 (0x3 << FC_FCTL_ACK_SHIFT)
#define FC_FCTL_ACK_MASK (0x3 << FC_FCTL_ACK_SHIFT)