Location of the .simrc File

Various Virtuoso tools load the .simrc file during the netlisting process. Depending on the project requirements or setup, a designer may keep the .simrc file at different locations. If your simulation setup contains a.simrc file at multiple locations, refer to the lookup order flowchart in the following figure to understand which of these files is selected for netlist customization.

This flowchart describes the locations and the sequence in which Virtuoso looks for a .simrc file. It also provides guidance to designers on the best location in which to place the .simrc file if they want Virtuoso to use it for netlist customization.

1. *Cadence Search Framework. For more details, see Cadence Setup Search File.

All netlisters first load the si.env file, which prepares the simulation environment. The.simrc file, if it exists, is loaded whenever netlisting starts in the simulation flow. This file overrides the settings defined in the si.env file and sets default variables for simulations run by a specific user or system without impacting other simulations.

The netlisters that use the .simrc file can be grouped into the following categories:

• Netlisters that are invoked by running the si -batch command at the command line or through interactive simulation.
  In this case, the .cdsinit file is not loaded and a separate si process is launched to perform the netlisting. The si.env is loaded, followed by the .simrc file, and changes in the current session, such as effective CDF modifications or other in-memory modifications, are visible in the netlist.
• Netlisters that run in the background when the Run in Background check box is selected in the Virtuoso GUI.
  For example, the CDL Out form used by Virtuoso lets you select or deselect the Run in Background check box. The .cdsinit file or the current environment is not used and in addition to the background virtuoso process, a separate si process is launched to perform the netlisting. The si.env is loaded, followed by the .simrc file. For example, CDL, Verilog, or VHDL. Changes in the current session are not visible in the netlist.
• Netlisters that are invoked when an OCEAN script is run at the command-line.
  The .oceanrc file is loaded, followed by si.env, and then the .simrc file during netlisting. In-memory modifications are visible in the netlist.
• Netlisters that are invoked by the Virtuoso GUI.
  For example, Spectre, HspiceD, CDL, Verilog, or VHDL. The si.env file is loaded, followed by the .simrc file. Changes in the current session, such as effective CDF modifications, .cdsinit modifications, or other in-memory modifications are visible in the netlist.
  
  Modifications through the .cdsinit file are only possible with the netlisters used by the Virtuoso GUI. For all other netlisters, simulations must be customized using the .simrc file.

The .simrc file is loaded during each netlist generation and can be loaded multiple times in a Virtuoso session. You can specify simulator-specific customizations by setting the simSimulator variable.

For example,

when( and( boundp('simSimulator) (simSimulator == "spectre"))
  printf("Specify Spectre options\n")
)

when( and( boundp('simSimulator) (simSimulator == "auCdl"))
  printf("Specify CDL options\n")
)

Related Topics

Netlist Generation and Customization

Netlist Customization With the .simrc File

Variables for Incremental Netlisting

Customization of Scale Factors

Substitution Functions