Back Annotation and Delay Calculation

Creating a Back Annotator

The routine acc_next_cell_load returns a handle to the load (primitive terminal) inside of the next cell instance that has an input or inout port driven by a specific net. This routine only returns one load handle for each cell input or inout port driven by the net. That is, if a cell input or inout port feeds more than one primitive terminal inside of the cell, only one of the primitive terminal handles will be returned by acc_next_cell_load. The terminal selection in this case is arbitrary. Use acc_next_cell_load to scan all of the cell loads on a net. Use the more general acc_next_load to scan all loads on a net.

The routine acc_count, when called with the acc_next_cell_load argument, returns the number of cell loads on a specific net. Use acc_count with the argument acc_next_load to count all loads on a net.

Effect of Source Protection

The following routines do not access data in protected regions of the source description of a design hierarchy, because they provide information that normally does not appear in cell library data books:

■acc_next_child

■acc_next_net

■acc_next_primitive

■acc_next_terminal

■acc_handle_object

■acc_handle_terminal

Other access routines provide information in data books and thus retrieve data in protected regions, but only when the data has one of these characteristics:

■it is a parameter

■it is associated with a module port—e.g., port names, delays on port drivers

■it resides in a specify block

This relationship between access routines and source protection maintains the integrity of the source protection facility while allowing for most delay back annotation and delay calculation implementations.

For more information about source protection, refer to the Verilog-XL Reference Manual.

Back Annotation and Delay Calculation

Creating a Back Annotator

Where to Look for More Information

Refer to the PLI 1.0 User Guide and Reference for detailed syntax and usage information on access routines used in these application notes.