11.4.1. The placement algorithm in TimberWolf
Simulated annealing based placement algorithm was popularized in the mid-1980s by the TimberWolf place-and-route package [Sechen 1986]. The Timber-Wolf standard-cell placement algorithm consists of two stages. Stage 1 allows overlaps among cells and movement of cells between rows. Stage 2 eliminates all overlaps and only performs interchange of adjacent cells. The details are described in the following.
126.96.36.199. Stage 1
In stage 1, a configuration is an arrangement of the cells into the standard-cell rows possibly with cell overlaps. Three moves are defined:
- M1: Move a cell to a new location, which can be in a different row.
- M2: Swap two cells, which can be in different rows.
- M3: Mirror a ...