code: func (t *Tx) Init(b []byte) {
  	t.p.init(b)
  	// maxPayloadSize excludes the header of the payload, and the header
  	// of the wrapping message.
  	t.maxPayloadSize = uint64(len(t.p.buffer)) - 2*sizeOfSlotHeader
  	t.tail = 0xfffffffe * jump
  	t.next = t.tail
  	t.head = t.tail + jump
  	t.p.write(t.tail, slotFree)
  }
docs: // Init initializes the transmit end of the pipe. In the initial state, the next
  // slot to be written is the very first one, and the transmitter has the whole
  // ring buffer available to it.