ADMS

ADMS is a public domain software to translate Verilog-A models into C-models which can be directly read by a number of SPICE simulators, including Spectre Circuit Simulator, Ngspice and HSpice.
Overview.
ADMS stands for Automatic Device Model Synthesizer.
ADMS can be used to turn Verilog-A compact models into C code. ADMS interpreter parses a Verilog-AMS file to build a data tree. XML filters are applied on the tree to generate the output files.
ADMS aims to reduce the effort of circuit simulator developers to integrate device models - at the same time, it provides the option to compact model developers to use the vendor-neutral language Verilog-A for model definition, improving robustness and maintainability.
ADMS is used by the open source SPICE simulator NGSPICE to support a number of compact models. Following models are supported by NGSPICE using ADMS:
Limitations.
ADMS only parses a subset of Verilog-A, and not all statements are supported by all XML filters. Specifically, current controlled voltage sources are not supported in most filters targeting SPICE simulators:
Instead, this needs to be represented as a conductance expression (and not impedance). 
i.e. I(..) <+ V(..)
Some other language constructions need to be supported in the filter as well
Many language features are hard to support with ADMS filters
Important aspects of code generation are close to impossible with ADMS
and