tailieunhanh - Sequential Verulog Topics part 9

PLI Interface provides a set of C interface routines to read, write, and extract information about the internal data structures of the design. Designers can write their own system tasks | Summary In this chapter we described the Programming Language Interface PLI for Verilog. The following aspects were discussed PLI Interface provides a set of C interface routines to read write and extract information about the internal data structures of the design. Designers can write their own system tasks to do various useful functions. PLI Interface can be used for monitors debuggers translators delay calculators automatic stimulus generators dump file generators and other useful utilities. A user-defined system task is implemented with a corresponding user-defined C routine. The C routine uses PLI library calls. The process of informing the simulator that a new user-defined system task is attached to a corresponding user C routine is called linking. Different simulators handle the linking process differently. User-defined system tasks are invoked like standard Verilog system tasks . hello_verilog . The corresponding user C routine hello_verilog is executed whenever the task is invoked. A design is represented internally in a Verilog simulator as a big data structure with sets for objects. PLI library routines allow access to the internal data structures. Access acc routines and utility tf routines are two types of PLI library routines. Utility routines represent the first generation of Verilog PLI. Utility routines are used to pass data back and forth across the boundary of user C routines and the original Verilog design. Utility routines start with the prefix tf_. Utility routines do not interact with object handles. Access routines represent the second generation of Verilog PLI. Access routines can read and write information about a particular object from to the design. Access routines start with the prefix acc_. Access routines are used primarily across the boundary of user C routines and internal data representation. Access routines interact with object handles. Value change link VCL is a special category of access routines that allow monitoring of