Introduction¶

What Is GTKWave?¶

GTKWave is a fully featured wave viewer based on GTK for Unix, Win32, and Mac OSX. It supports various file formats including FST, LXT, LXT2, VZT, GHW, and standard Verilog VCD/EVCD files. Primarily used for debugging Verilog or VHDL simulation models, GTKWave is designed for post-mortem analysis by analyzing dumpfiles rather than real-time interaction during simulations. It allows the visualization of both analog and digital data, supports various search operations, and enables users to save “signals of interest” extracted from a complete simulation dump. Additionally, GTKWave can generate outputs in PostScript and FrameMaker formats for hard copy documentation.

GTKWave also includes a suite of helper applications designed for specialized tasks such as file conversion, RTL parsing, and other data manipulation operations that extend beyond the typical scope of a visualization tool. These applications are meant to work together as a cohesive system. However, their modular design also allows them to operate independently if necessary.

Why Use GTKWave?¶

GTKWave has been developed to perform debug tasks on large systems on a chip and has been used in this capacity as an offline replacement for third-party debug tools. It is 64-bit clean and is ready for the largest of designs given that it is run on a workstation with a sufficient amount of physical memory. The file format FST has been designed to handle extremely large, real-world designs efficiently.

For Verilog, GTKWave allows users to debug simulation results at both the net level by providing a bird’s eye view of multiple signal values over varying periods of time and also at the RTL level through annotation of signal values back into the RTL for a given timestep (see RTLBrowser). The RTL browser frees up users from needing to be concerned with the actual location of where a given module resides in the RTL as the view provided by the RTL browser defaults to the module level. This provides quick access to modules in the RTL as navigation has been reduced simply to moving up and down in a tree structure that represents the actual design.

Source code annotation is currently not available for VHDL. However, all of GTKWave’s other debug features are readily accessible. VHDL support is planned for a future release.