FM10K_MSG_HDR_MASK
if (!head || (head == FM10K_MSG_HDR_MASK(HEAD)))
if (!tail || (tail == FM10K_MSG_HDR_MASK(TAIL)))
if (!head || (head == FM10K_MSG_HDR_MASK(HEAD)))
(((u32)(value) & FM10K_MSG_HDR_MASK(name)) << FM10K_MSG_##name##_SHIFT)
((u16)((value) >> FM10K_MSG_##name##_SHIFT) & FM10K_MSG_HDR_MASK(name))