Add system library of Verilog-A defined devices

[ra3xdh]

The microstrip devices models #94 will be most likely implemented in form of Verilog-A modules. These modules should be compiled with OpenVAF and attached to Ngspice. It's need to provide a way to attach Verilog-A model to system devices. I propose the following approach:

• Put a set of VA models in share/qucs-s/va_library directory in the installation root.

The two ways to integrate these models are possible:

• Add a button named like Compile system libraries in the application setting dialog near the OpenVAF configuration input field. Compiled OSDI modules will be placed to the $HOME/.qucs/osdi_modules location and attached automatically while forming .spiceinit config. Modules should be build once.

• Scan schematic recursively and compile OSDI modules automatically before the simulation if some device referencing Verilog-A model is found.

The combination of these two approaches is also possible. This feature should be added in order to implement #94 in the next release.

[zergud]

there is a more flexible solution for library location:

• SYSTEM - located in share/qucs-s/va_library (readonly)
• USER - located in user home dir $HOME/.qucs/va_library
• PROJECT - located in project folder

USER and PROJECT directory are writeble for user

all compiled OSDI modules will be placed to the $HOME/.qucs/osdi_modules location and attached automatically while forming .spiceinit config

compilation approach, control duplicated name and recompilation condition (e.g. via file timestamp) are subject to discuss

[ra3xdh]

The development of the OpenVAF compiler seems to be suspended. See pascalkuthe/OpenVAF#111 (comment) for more details. By this reason I am removing this issue from the development plan for the next release. Let's wait for more news about OpenVAF future, because the support of Verilog-A in Qucs-S+Ngspice is strongly depends on OpenVAF.