VCS Simulation Configuration

Environment variable

You should have several environment variables defined before:

VCS_HOME: The home path to your VCS installation.
VERDI_HOME: The home path to your Verdi installation.
Add $VCS_HOME/bin and $VERDI_HOME/bin to your PATH.

Prepend the following paths to your LD_LIBRARY_PATH to enable PLI features.

export LD_LIBRARY_PATH=$VERDI_HOME/share/PLI/VCS/LINUX64:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH=$VERDI_HOME/share/PLI/IUS/LINUX64:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH=$VERDI_HOME/share/PLI/lib/LINUX64:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH=$VERDI_HOME/share/PLI/Ius/LINUX64:$LD_LIBRARY_PATH
export LD_LIBRARY_PATH=$VERDI_HOME/share/PLI/MODELSIM/LINUX64:$LD_LIBRARY_PATH

If you encounter the Compilation of SharedMemIface.cpp failed error, make sure that you have installed C++ boost library correctly. The header and library files path should be added to CPLUS_INCLUDE_PATH, LIBRARY_PATH and LD_LIBRARY_PATH respectively.

User defined environment setup

Sometimes a VCS environment setup file synopsys_sim.setup is required to run VCS simulation. Also you may want to run some scripts or code to setup the environment just before VCS starting compilation. You can do this by withVCSSimSetup.

val simConfig = SimConfig
  .withVCS
  .withVCSSimSetup(
    setupFile = "~/work/myproj/sim/synopsys_sim.setup",
    beforeAnalysis = () => { // this code block will be run before VCS analysis step.
      "pwd".!
      println("Hello, VCS")
    }
  )

This method will copy your own synopsys_sim.setup file to the VCS work directory under the workspacePath (default as simWorkspace) directory, and run your scripts.

VCS Flags

The VCS backend follows the three step compilation flow:

Analysis step: analysis the HDL model using vlogan and vhdlan.
Elaborate step: elaborate the model using vcs and generate the executable hardware model.
Simulation step: run the simulation.

In each step, user can pass some specific flags through VCSFlags to enable some features like SDF back-annotation or multi-threads.

VCSFlags takes three parameters,

Name	Type	Description
`compileFlags`	`List[String]`	Flags pass to `vlogan` or `vhdlan`.
`elaborateFlags`	`List[String]`	Flags pass to `vcs`.
`runFlags`	`List[String]`	Flags pass to executable hardware model.

For example, you pass the -kdb flags to both compilation step and elaboration step, for Verdi debugging,

val flags = VCSFlags(
    compileFlags = List("-kdb"),
    elaborateFlags = List("-kdb")
)

val config =
  SimConfig
    .withVCS(flags)
    .withFSDBWave
    .workspacePath("tb")
    .compile(UIntAdder(8))

...

Waveform generation

VCS backend can generate three waveform format: VCD, VPD and FSDB (Verdi required).

You can enable them by the following methods of SpinalSimConfig,

Method	Description
`withWave`	Enable `VCD` waveform.
`withVPDWave`	Enable `VPD` waveform.
`withFSDBWave`	Enable `FSDB` waveform.

Also, you can control the wave trace depth by using withWaveDepth(depth: Int).

Simulation with `Blackbox`

Sometimes, IP vendors will provide you with some design entities in Verilog/VHDL format and you want to integrate them into your SpinalHDL design. The integration can done by following two ways:

In a Blackbox definition, use addRTLPath(path: String) to assign a external Verilog/VHDL file to this blackbox.
Use the method mergeRTLSource(fileName: String=null) of SpinalReport.