There are three ``notebook'' tabs that correspond to the three types of CGD. Each corresponding page contains controls for setting the parameters appropriate for the selected CGD type.
The source from which to create the CGD is entered into the entry area at the top of the page. The source can be one of the following:
If the source is a layout file, one can apply layer filtering as the file is being read. It is also possible to apply cell name mapping. If mapping is employed, layer data are accessed via the modified cell names. If the CGD is to be linked with a CHD, the cell name mapping, if any is used, should be the same when creating the CHD and the CGD. The control groups below the entry expose the layer filtering and cell name mapping capabilities.
If the source is a CHD access name, or a CHD file, the cell name mapping is automatically set to the same as was used in creating the CHD. The layer filtering is available if the source is a CHD access name, or if the source is a CHD file saved without geometry records (with the Save button in the Cell Hierarchy Digests panel). If the source is a CHD file containing geometry records, the CGD uses those geometry records verbatim.
If the source is a saved CGD file (from the Save button in the Cell Geometry Digests panel), the CGD will import this file verbatim.
This page consists of an entry area, into which a source is entered. The source can be either a path to a saved CGD file, or to a saved CHD file that contains geometry records. In either case, the new CGD is created to reference the geometry data by offset into the source file.
During its lifetime, this type of CGD maintains an open file descriptor to its source file. Although it is not likely, it may be possible to hit a system limit for open file descriptors if too many file CGDs are simultaneously open.
This page provides separate entry areas for the host name, port, and remote CGD access name. These correspond to the remote host running the Xic server, which must have a CGD in memory (of any type). The new CGD will transparently link to the remote CGD, under a local access name.
The Host name entry must contain the network host name of the machine running the server. The Port number is optional, if not specified the port used defaults to 6115, which is the IANA registered port number for the ``xic/tcp'' service. If the server is for some reason using a different port number, that same port number must be entered. The access name of the CGD to reference on the server must be entered into the Server CGD access name entry area.
During its lifetime, this type of CGD maintains an open socket to the server. Since the number of connections is limited, it is best to free this type of CGD as soon as possible.
Below the notebook area is an entry for access name. This is the name under which the new CGD will be listed in the Cell Geometry Digests panel. A default is provided that is guaranteed not to conflict with an existing CGD.
The user can specify an access name. If the name is in use by an existing CGD, and the existing CGD is not linked to a CHD, it will be destroyed, and the new CGD will be created and saved under the same name. However, if the existing CGD is linked, it cannot be destroyed, and the CGD creation will fail with an error message.
When the Apply button is pressed, if all goes properly the source will be processed, the new CGD will be created, and added to the list in memory under the access name given.