plusargs_examples

plusargs_examples — Enhancement-215: $test$plusargs / $value$plusargs

Command-line plusargs let a Verilog-A model read +name[=value] arguments passed to ngspice, so a corner or a feature flag is chosen at run time without editing the deck:

ngspice -b deck.cir +corner=ff      # $value$plusargs("corner=%s", c)  -> c = "ff"
ngspice -b deck.cir +gain=25        # $value$plusargs("gain=%d", n)    -> n = 25
ngspice -b deck.cir +boost          # $test$plusargs("boost")          -> true

Before E-215 these were the constant fallbacks of Enhancement-12: $test$plusargs always returned false and $value$plusargs never wrote its output. They are now served through the OSDI simparam channel — ngspice collects each +-argument and a compiled model looks it up — with no OSDI ABI change.

How it works

• ngspice (main.c, osdiload.c): each +name[=value] on the command line is registered and exposed as namespaced simparams — $test$plusargs$name (present), $valset$plusargs$name (given in name=value form), $valnum$plusargs$name (the value as a number) and $value$plusargs$name (the value as a string).
• openvaf-r lowers $test$plusargs("name") to a presence lookup and $value$plusargs("name=%fmt", var) to a value lookup by the target's type (number or string), writing var and returning whether a value was matched.

$value$plusargs matches only the name=value form (a bare +gain is not a value match), exactly as the LRM specifies.

Files

File	What it is
plusargs_demo.va	A conductance set from plusargs — presence (+boost), integer (+gain=n), real (+scale=x) and string (+corner=ff|ss) — observable as a DC current.
verify_plusargs.py	12 checks (compile + the full plusarg matrix), both solvers.

Run

python3 verify_plusargs.py