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Programming Language interface part 2

[ Team LiB ] 13.4 PLI Library Routines PLI library routines provide a standard interface to the internal data representation of the design. The user-defined C routines for user-defined system tasks are written by using PLI library routines. In the example in Section 13.2 | Team LiB 13.4 PLI Library Routines PLI library routines provide a standard interface to the internal data representation of the design. The user-defined C routines for user-defined system tasks are written by using PLI library routines. In the example in Section 13.2 Linking and Invocation of PLI Tasks hello_verilog is the user-defined system task hello_verilog is the user-defined C routine and io_printf is a PLI library routine. There are two broad classes of PLI library routines access routines and utility routines. Note that vpi_ routines are a superset of access and utility routines and are not discussed in this book. Access routines provide access to information about the internal data representation they allow the user C routine to traverse the data structure and extract information about the design. Utility routines are mainly used for passing data across the Verilog Programming Language Boundary and for miscellaneous housekeeping functions. Figure 13-6 shows the role of access and utility routines in PLI. Figure 13-6. Role of Access and Utility Routines A complete list of PLI library routines is provided in Appendix B List of PLI Routines. The function and usage of each routine are also specified. 13.4.1 Access Routines Access routines are also popularly called acc routines. Access routines can do the following Read information about a particular object from the internal data representation Write information about a particular object into the internal data representation We will discuss only reading of information from the design. Information about modifying internal design representation can be found in the Programming Language Interface PLI Manual. However reading of information is adequate for most practical purposes. Access routines can read information about objects in the design. Objects can be one of the following types Module instances module ports module pin-to-pin paths and intermodule paths Top-level modules Primitive instances primitive .