Designing with Low-Level Primitives Chapter 2. Primitive Reference Primitives ................................................................................................................................................ 2–1 ALT_INBUF ...................................................................................................................................... 2–1 ALT_OUTBUF .................................................................................................................................. 2–3 ALT_OUTBUF_TRI .......................................................................................................................... 2–6 ALT_IOBUF ....................................................................................................................................... 2–8 ALT_INBUF_DIFF ......................................................................................................................... 2–11 ALT_OUTBUF_DIFF ..................................................................................................................... 2–13 ALT_OUTBUF_TRI_DIFF ............................................................................................................. 2–14 ALT_IOBUF_DIFF .......................................................................................................................... 2–19 ALT_BIDIR_DIFF ........................................................................................................................... 2–22 ALT_BIDIR_BUF ............................................................................................................................ 2–25 LCELL .............................................................................................................................................. 2–27 DFF ................................................................................................................................................... 2–28 CARRY and CARRY_SUM ........