Icarus Verilog is a Verilog simulation and synthesis tool. It operates as a compiler, compiling source code writen in Verilog (IEEE-1364) into some target format. For batch simulation, the compiler can generate C++ code that is compiled and linked with a run time library (called "vvm") then executed as a command to run the simulation. For synthesis, the compiler generates netlists in the desired format. The compiler proper is intended to parse and elaborate design descriptions written to the IEEE standard IEEE Std 1364-2000. The standard proper is due to be release towards the middle of the year 2000. This is a fairly large and complex standard, so it will take some time for it to get there, but that's the goal.