ModelSim SE User's Manual - Electrical and Computer Engineering

UM-84 4 - VHDL simulation
Modifying stimulus
Using with the PLI or FLI
Syntax
ModelSim SE User’s Manual
A primary use of elaboration files is repeatedly simulating the same design with different
stimulus. The following mechanisms allow you to modify stimulus for each run.
Use of the change command to modify parameters or generic values. This affects values
only; it has no effect on triggers, compiler directives, or generate statements that
reference either a generic or parameter.
Use of the -filemap_elab = argument to establish a
map between files named in the elaboration file. The file name, if it
appears in the design as a file name (for example, a VHDL FILE object as well as some
Verilog sysfuncs that take file names), is substituted with the file
name. This mapping occurs before environment variable expansion and can’t be used to
redirect stdin/stdout.
VCD stimulus files can be specified when y ou load the elaboration file. Both vcdread and
vcdstim are supported. Specifying a different VCD file when you load the elaboration file
supersedes a stimulus file you specify when you create the elaboration file.
In Verilog, the use of +args which are readable by the PLI routine mc_scan_plusargs().
+args values specified when you create the elaboration file are superseded by +args
values specified when you load the elaboration file.
PLI models do not require special code to function with an elaboration file as long as the
model doesn't create simulation objects in its standard tf routines. The sizetf, misctf and
checktf calls that occur during elaboration are played back at -load_elab to ensure the PLI
model is in the correct simulation state. Registered user tf routines called from the Verilog
HDL will not occur until -load_elab is complete and the PLI model's state is restored.
By default, FLI models are activated for checkpoint during elaboration file creation and are
activated for restore during elaboration file load. (See the "Using checkpoint/restore with
the FLI" section of the FLI Reference manual for more information.) FLI models that
support checkpoint/restore will function correctly with elaboration files.
FLI models that don't support checkpoint/restore may work if simulated with the
-elab_defer_fli argument. When used in tandem with -elab, -elab_defer_fli defers calls to
the FLI model's initialization function until elaboration file load time. Deferring FLI
initialization skips the FLI checkpoint/restore activity (callbacks, mti_IsRestore(), ...) and
may allow these models to simulate correctly. However, deferring FLI initialization also
causes FLI models in the design to be initialized in order with the entire design loaded. FLI
models that are sensitive to this ordering may still not work correctly even if you use
-elab_defer_fli.
See the vsim command (CR-373) for details on -elab, -elab_cont, -elab_defer_fli,
-compress_elab, -filemap_elab, and -load_elab.