CLI Reference

Synopsis

nexsim [FILES]... --top <TOP> --run-time <RUN_TIME> [OPTIONS]

Arguments

Argument	Required	Description
[FILES]...	Yes	One or more VHDL source files

Options

Flag	Short	Required	Default	Description
--top <TOP>	-t	Yes	—	Top-level entity name
--run-time <RUN_TIME>	-r	Yes	—	Simulation duration in nanoseconds
--output <OUTPUT>	-o	No	output.vcd	Output VCD file path
--open <VIEWER>	—	No	—	Open VCD after simulation

--open values

Value	Description
nexsim	Open in the nexsim viewer
gtkwave	Open in GTKWave
surfer	Open in Surfer

Examples

# Basic simulation
nexsim alu.vhd alu_tb.vhd -t alu_tb -r 1000

# Custom output path
nexsim alu.vhd alu_tb.vhd -t alu_tb -r 1000 -o result.vcd

# Open with GTKWave after simulation
nexsim alu.vhd alu_tb.vhd -t alu_tb -r 1000 --open gtkwave

# Multi-file hierarchical design
nexsim pkg.vhd sub.vhd top.vhd top_tb.vhd -t top_tb -r 5000

Output

On success:

Running VHDL simulation for 1000ns...
Simulation completed successfully!
VCD file generated: output.vcd

On failure, one of:

Compilation failed: <error details>
Elaboration failed: <error details>

Exit codes

Code	Meaning
0	Success
non-zero	Compilation, elaboration, or simulation error