Flat Mode Options

None of the per-cell options apply in flat mode, though with the exception of -e if given they will be benignly ignored. Flat mode applies only to physical data, and if -e is given, an error will result.

In flat mode, both source tokens must be provided, as flat comparison to memory cells is not available.

-a L,B,R,T
The -a option specifies the rectangular area where comparison is performed. If not given, comparison is performed over the entire cell area of both cells. The word that follows -a consists of the four rectangle coordinate values, in microns, separated by commas. There can be no white space.

The flat geometry mode is somewhat orthogonal to the other modes. The algorithm uses two levels of gridding to partition the layout into pieces, and directly compares the geometry in each fine grid cell. This is very similar to the algorithm described for the ChdIterateOverRegion script function.

-i fine_grid
This sets the size of the fine grid used for comparison. The geometry in each fine grid cell is compared. The value is in microns in the range 1.0 - 100.0, if not given 20.0 is used.

-m coarse_mult
This sets the size of the coarse grid, as an integer multiple of the fine grid size. The coarse grid size is the chunk size for reading geometry into memory. Once in memory, the geometry is split into the fine grid cells and compared. Using too large of a coarse grid can cause memory exhaustion for dense layouts, but on the other hand a larger coarse grid size usually improves speed. The user should experiment to find the best values for the fine and coarse grid for their layouts. The acceptable range for this parameter is 1 - 100. If not given, 20 is used.