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Further Synthesis Issues

There are many combinational circuits that have the same functionality.

Synthesis tools can accept additional guiding metrics from the user, that affect

(The basic algorithm in the additional material does not consider any guiding metrics.)

Gate libraries have high and low drive stength forms of most gates (see later).

Some leaf cells are broadside and do not require bit-blasting.

The tool will use Quine/McCluskey, Espresso or similar for logic minimisation.

   reg[31:0] y;
   if (e1) y <= e2; 
   else if (e3) y <= e4; 
   else y <= 32'bx;              // Note, assignment of 'x' permits automated logic minimisation.

Can share sub-expressions or re-compute expressions locally.

Can re-encode state (see later).

24: (C) 2008-13, DJ Greaves, University of Cambridge, Computer Laboratory. Flash Player Upgrade Needed   PLAY/PAUSE  READY    STOP DOWNLOAD