3. FLOORPLAN AND PLACEMENT ALGORITHMS
3.1 Floorplanning scheme We assume the area size of each module is 1 unit to find the minimal wiring cost pattern. This optimal pattern is used as a main guideline to construct the actual area in the placement process. A practical pattern will be occurred. SA based on top-down multilevel partitioning placement flow used in [7][9] is applied in our placement process. The input circuits are recursively partitioned into rows in order to maintain minimal area size with row based concept. The total working area is
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Where n is the number of modules. The floorplan is rearranged for the smallest wiring cost by fixing total width *** of each row and adjusting height *** of each row. The shape of working area is assumed to be square. The total width *** of each row is defined as (or else identified by a system designer).
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Each row is separated by a cutting which is a designed pattern for crosstalk minimization. At the first step of the procedure, the cooling temperature in SA algorithm is set to be very high where row exchange scheme is initially applied. Then the current solution is evaluated for its fitness value which is the total wiring cost, shown in Eq. (3) . After the temperature is cooling down to a certain point, the module exchange scheme is randomly applied.
There are 2 interchange schemes. Rox-exchange scheme is used when T is high. Module exchange scheme is used when T low. Row-exchange scheme: Find a pair of rows that are separated in the y dimension in the give pattern and swap all members between selected rows. Module-exchange scheme: Find new pattern by exchanging positions of the two selected modules. For detailed description of the floorplan algorithm, see Fig.2.