Constraints in Floor planning of vlsi layout

In floorplanning, it is important to allow users to specify placement constraints. Three common types of placement constraints are preplaced constraint, boundary constraint, and range constraint. For preplaced constraint, we require a block to be placed exactly at a certain position in the final packing. For boundary constraint, we require a block to be placed along one particular side of the final floorplan: on the left, on the right, at the bottom, or at the top. This is useful when users want to place some specific block along the boundary for input–output connections. For range constraint, we require a module to be placed within a given rectangular region in the final packing. This is indeed a more general formulation of the placement constraint problem and any preplaced constraint can be written as a range constraint by specifying the rectangular region such that it has the same size as the module itself. Some representations and algorithms for floorplan are extended for above given constraints.