FIX_IPD_NON_FIRST_BUFF_PAYLOAD_BYTES
((num_segs - 1) * FIX_IPD_NON_FIRST_BUFF_PAYLOAD_BYTES) -
(FIX_IPD_NON_FIRST_BUFF_PAYLOAD_BYTES / 2);
FIX_IPD_NON_FIRST_BUFF_PAYLOAD_BYTES;