save

The Tcl save command creates a snapshot of the current simulation state. You can then use the restart command to load the saved snapshot and resume simulation.

You may only issue the save command when the simulator is at certain points in its execution cycle.

The simulator cannot be in the middle of executing procedural statements. To run the simulation to the next point at which the save command will work, use the run -clean command.

For mixed-signal designs, the simulator must have accepted at least one transient time step.

If your files are very large, you might encounter a limit on the size of a file. If a library database exceeds this limit, you cannot add objects to the database. If you save many snapshot checkpoints to unique views in a single library, this file size limit could be exceeded. If you reach this limit, you can:

Use save -overwrite to overwrite an existing snapshot. For example,
xcelium> save -simulation -overwrite snap1

Save snapshots to a separate library. For example,
mkdir xcelium.d/snaplib xmsim -f xmsim.args xcelium> run 1000 ns xcelium> save -simulation snaplib.snap1 xcelium> run 1000 ns xcelium> save -simulation snaplib.snap2

Remove snapshots using the xmrm utility. For example,
xmrm -snapshot worklib.snap1

save Command Syntax

save -simulation <snapshot_name> [-overwrite]
-environment [filename] -commands [filename]

save Command Options

This section describes the options that you can use with the Tcl save command.

`-simulation snapshot_name`	Creates a snapshot of the current simulation state. The snapshot also contains the analog control options in effect at the time of the save. This option is the default. You must specify a snapshot name with the `save` command. The snapshot name can be specified using the `[lib.]cell[:view]` notation, or, if you want the snapshot to be a new view of the currently loaded cell, you can specify just the view name preceded by a colon. For example, if you are simulating `worklib.top:rtl,` `save ckpt1` Saves `worklib.ckpt1:rt` `save top:ckpt1` Saves `worklib.top:ckpt1` `save otherlib.top` Saves `otherlib.top:rtl` `save :ckpt1` Saves `worklib.top:ckpt1` The snapshot name must be a simple name containing only letters, numbers, and underscores. By default, the saved snapshot is saved either in the library you specify or in the work library (if you do not specify a library).
`-overwrite`	Overwrites an existing snapshot.
`-environment [filename]`	Creates a Tcl script that captures the current breakpoints, databases, probes, aliases, and predefined Tcl variable values. The `filename` argument is optional. If no filename is specified, the script is written to standard output. The state of the Tcl debug environment is not part of the simulation that is saved in a snapshot. To save the debug environment, you must issue a separate `save -environment` command. This command creates a Tcl script that captures the current breakpoints, databases, probes, aliases, and predefined Tcl variable values. You can then restore the environment by executing this script with the Tcl `source` command, or you can use the `-input` option when you start the simulator. For example: `xcelium> save :ckpt1` `xcelium> save -environment ckpt1.tcl` `xcelium> restart :ckpt1` `xcelium> source ckpt1.tcl` or `xcelium> -tcl cell:ckpt1 -input ckpt1.tcl)` These scripts are meant to be sourced into an empty environment (that is, an environment with no breakpoints, no probes, no databases). If you start the simulator, set some breakpoints and probes, and then source a script that contains commands to set breakpoints and probes, the simulator will probably generate errors telling you that some commands in the script could not be executed. These errors are due to name conflicts. For example, you may have set a breakpoint that received the default name "1", and the command in the script is trying to create a breakpoint with the same name. You can, of course, give your breakpoints unique names to avoid this problem. You can also edit the scripts to make them work the way you would like them to work.
`-commands` [`filename`]	`save -commands` is the same as `save -environment.`

save Command Examples

The section includes the examples of how the save command in the following scenarios:

How to Save a Snapshot of the Current Simulation State

How to Use the save -environment Command

How to Use save, restart, and analog

How to Save a Snapshot of the Current Simulation State

The following command saves the simulation state in lib . cell :ckpt1, where lib is the name of the current work library, and cell is the cell name of the currently loaded snapshot.

xcelium> save -simulation :ckpt1

The following command saves the simulation state in lib .top:ckpt1.

xcelium> save top:ckpt1

The following command saves the simulation state in lib .ckpt1: view_name, where view_name is the view name that is currently being simulated.

xcelium> save ckpt1

How to Use the save -environment Command

The following example illustrates how to use the save -environment command.The right column annotates the behavior of each command.

Commands	Notes
`xcelium -tcl hardrive xmsim: v2.1.(p1): (c) Copyright 1995 - 2003 Cadence Design Systems` `Loading snapshot worklib.hardrive:module .... Done`	Start the simulator.
`xcelium> stop -create -line 32 Created stop 1 xcelium> stop -create -object hardrive.clkCreated stop 2 xcelium> probe -create -shm hardrive.data Created default SHM database xcelium.shm Created probe 1`	Set a line breakpoint, an object breakpoint, and create a probe. The probe command creates a default SHM database.
`xcelium> run 0 FS + 0 (stop 2: hardrive.clk = 0)./hardrive.v:13 clk = 0;`
`xcelium> run 50 NS + 0 (stop 2: hardrive.clk = 1)./hardrive.v:16 always #50 clk = ~clk;`
`xcelium> save -environment env1.env`	Save the debug settings in a file called `env1.env.`
`xcelium> more env1.env` `set assert_report_level {note} set assert_stop_level {error} set autoscope {yes} set display_unit {auto} set tcl_prompt1 {puts -nonewline "xmsim> "} set tcl_prompt2 {puts -nonewline "> "} set time_unit {module}set vlog_format {%h} set assert_1164_warnings {yes} stop -create -name 1 -line 32 hardrive stop -create -name 2 -object hardrive.clk database -open -shm -into xcelium.shm xcelium.shm -defaultprobe -create -name 1 -database xcelium.shm hardrive.datascope -set hardrive`	Look at the file contents.
`xcelium> exit`	Exit from the simulator.
`foghorn% xmsim -tcl hardrivexcelium: v1.2.(b9): (c) Copyright 1995 - 2000 Cadence Design Systems` `Loading snapshot worklib.hardrive:module .................... Done`	Restart the simulator.
`xcelium> stop -showNo stops set`	The new session has no breakpoints.
`xcelium> source env1.env`	Source the `env1.env` file.
`xcelium> stop -show1 Enabled Line: ./hardrive.v:32 (scope: hardrive)2 Enabled Object hardrive.clkxcelium> probe -show1 Enabled hardrive.data (database: xcelium.shm) -shmxcelium> database -showxcelium.shm Enabled (file: xcelium.shm) (SHM) (default)`	Show the status of breakpoints, probes, and databases.

How to Use save, restart, and analog

You can use the save, restart , and analog commands during transient analysis of a mixed-signal simulation in interactive mode (under -tcl or -gui). In non-interactive mode or if there is other analysis after the transient analysis specified analog control file, these commands are ignored when the simulation has reached the analog stop time of the transient analysis.

The analog -stop option is ignored with a warning message when .probe is used in the analog control file.

The following example illustrates how to use the save, restart and analog commands in interactive mode. The right column annotates the behavior of each command.

Commands	Notes
`xcelium> database -open waves -into waves.shm -default Created default SHM database waves`	Open a default SHM database called `waves.`
`xcelium> probe -create -all Created probe 1`	Probe all signals in the current scope.
`xcelium> stop -create -time -absolute 200ns Created stop 1`	Create a breakpoint at absolute time 200ns.
`xcelium> run 200 NS + 0 (stop 1)`	Run until 200ns.
`xcelium> analog -show vabstol = 1.000000e-06 (alterable) iabstol = 1.000000e-12 (alterable) reltol = 1.000000e-03 (alterable) stop = 14 us (alterable)`	Examine the tolerance values and stop time.
`xcelium> save :ckpt1 Saved snapshot amslib.top:ckpt1`	Save the first snapshot
`xcelium> analog -stop 20 us`	Lengthen the simulation.
`xcelium> analog -reltol 5e-03`	Change the `reltol` value.
`xcelium> analog -show vabstol = 1.000000e-06 (alterable) iabstol = 1.000000e-12 (alterable) reltol = 5.000000e-03 (alterable) stop = 20 us (alterable)`	Examine the new values.
`xcelium> stop -create -time -absolute 400ns Created stop 2`	Create another breakpoint.
`xcelium> run 400 NS + 0 (stop 2)`	Run until 400ns.
`xcelium> save :ckpt2 Saved snapshot amslib.top:ckpt2`	Save the second snapshot.
`xcelium> restart :ckpt1 Loaded snapshot amslib.top:ckpt1`	Reload the first snapshot.
`xcelium> analog -show vabstol = 1.000000e-06 (alterable) iabstol = 1.000000e-12 (alterable) reltol = 1.000000e-03 (alterable) stop = 14 us (alterable)`	Check that tolerance values and stop time are the same values you had originally...
`xcelium> time 200 NS`	...and that you are back at 200ns in the simulation.
`xcelium> restart :ckpt2 Loaded snapshot amslib.top:ckpt2`	Now reload the second snapshot.
`xcelium> analog -show vabstol = 1.000000e-06 (alterable) iabstol = 1.000000e-12 (alterable) reltol = 5.000000e-03 (alterable) stop = 20 us (alterable)`	Check for the changed `reltol` value and the lengthened simulation.
`xcelium> time 400 NS`	Run to 400ns, again!
`xcelium> run 200 NSRan until 600 NS + 0`	Run another 200ns.
`xcelium> restart :ckpt1 Loaded snapshot amslib.top:ckpt1`	Switch back to the first snapshot.
`xcelium> time 200 NS`	Check where you are.
`xcelium> run The analog simulator has reached stop time, please use analog -stop <new stop time> to extend the analog stop time.` `Simulation complete via transient analysis stoptime at time 14 US Memory Usage - 19.4M program + 13.5M data = 32.9M total CPU Usage - 0.6s system + 3.6s user = 4.2s total (1.1% cpu)`	Run until analog stop time.
`xcelium> analog -stop 100us`	At analog stop time, you can still lengthen the simulation.
`xcelium> run` `The analog simulator has reached stop time, please use analog -stop <new stop time>' to extend the analog stop time.` `Simulation complete via transient analysis stoptime at time 100 US` `Memory Usage - 19.4M program + 13.5M data = 32.9M total CPU Usage - 0.6s system + 23.6s user = 24.2s total (1.1% cpu`	Run until analog stop time.
`xcelium> restart :ckpt1 Loaded snapshot amslib.top:ckpt1`	At analog stop time, you can still restart a snapshot.
`xcelium> exit` `Number of accepted tran steps = 3161.` `Initial condition solution time = 200 ms.` `** AMSD: Mixed-Signal Activity Statistics **` `Number of A-to-D events: 24` `Number of A-to-D events in IEs: 0` `Number of D-to-A events: 16` `Number of D-to-A events in IEs: 0` `Number of VHDL-AMS Breaks: 0` `Intrinsic tran analysis time = 3.5 s.` `Total time required for tran analysis tran1 was 23.7 s.`	Exit and complete the simulation.