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Encounter supports three type of physical floorplan constraints namely guide, region and fence. Additionally, a fourth constraint of block is used to represent hard macros or hard blocks.
The guide constraint is the loosest of all floorplan constraints in Encounter. It roughly defines an area in which the user asks the tool to place the cells of a given module.
The guide constraint will be automatically assigned to a module when it is moved or placed inside the core area. Cells from modules that are not part of the guide may be placed inside the guide if the area is under utilized. Likewise cells from the modules defining the guide may be placed outside if the area is over utilized. To summarize, A guide is a soft indicant for placement of cells which says " I can let some cells in and let some cells out!"
Guides are Pink in color in the standard Encounter GUI.
The "region" constraint is still a loose constraint but its stronger than the "guide". When a "region" is defined it requires all the cells of the modules contained in the defined region to be placed in the specified region area. If extra space in the region exists, other cells from other modules can be brought inside. To summarize, a region is a stronger indicant for the placemnt of cells which says " I can let some cells in but will not let anything out!"
Regions are light brown in color in the standard Encounter GUI.
The "fence" constraint is the strongest floorplan constraint that one can have in Encounter. The fence constraint does not allow cells from other modules to be placed inside even if the area is under utilized. Also the cells in a fenced area cannot be placed outside of the defined fence.
A fence is meant to be exclusive, although not completely. In cases especially when the fence is too small, or there are buffers in the design. To summarize, A fence is the strongest indicant for the placemnt of cells which says " I neither let cells in nor will I let anything out!"
Fences are dark brown in color in the standard (not-customized ) Encounter GUI.