directive_examples

Compiler directive examples (version7 / Enhancement-6)

Self-contained correctness example for the ten Verilog-A/AMS compiler directives added in Enhancement-6 (`default_discipline, `celldefine/`endcelldefine, `unconnected_drive/ `nounconnected_drive, `timescale, `line, `pragma, `undefineall, `default_nettype), covering DC, AC, and Transient analysis. Everything here uses the version7 toolchain:

• compiler : ../OpenVAF-master-20260610/target/opt/openvaf-r
• simulator: ../ngspice-46/build/src/ngspice

See ../Enhancement-6.md (§1) for the full implementation writeup — before this enhancement, every one of these directives hard-failed compilation as an undefined macro call instead of being parsed/ignored, which broke real foundry .va files that carry this boilerplate.

The model: a gain buffer wrapped in every new directive

directive_demo.va is an ordinary gain buffer (V(out) <+ gain * V(in)), deliberately wrapped in all ten directives to prove they no longer break compilation:

`default_discipline electrical
`default_nettype none
`celldefine
`timescale 1ns/1ps
`unconnected_drive pull1
`include "disciplines.vams"

module directive_demo(in, out);
    inout in, out;
    electrical in, out;
    parameter real gain = 0.5 from (0:inf);
    analog begin
        V(out) <+ gain * V(in);
    end
endmodule

`nounconnected_drive
`endcelldefine
`pragma protect begin
`pragma protect end
`undefineall

Results

Analysis	Sweep	Expected	Observed
DC	V(in) −1V to 2V	out = 0.5 * in	exact match (dc_plot.png)
AC	1Hz–100MHz	flat 0.5 gain (≈ −6dB), 0° phase	flat, matches (ac_plot.png)
Transient	10kHz sine	output = 0.5× scaled sine	matches (tran_plot.png)

Layout

directive_examples/
  directive_demo.va    gain buffer wrapped in all 10 new directives
  directive_demo.osdi  compiled with version7 openvaf-r
  dc_sim.cir / ac_sim.cir / tran_sim.cir
  dc_result.txt / ac_result.txt / tran_result.txt   raw wrdata output
  dc_plot.png / ac_plot.png / tran_plot.png

Reproduce

OPENVAF=../OpenVAF-master-20260610/target/opt/openvaf-r
NGSPICE=../ngspice-46/build/src/ngspice

$OPENVAF directive_demo.va -o directive_demo.osdi
$NGSPICE -b dc_sim.cir
$NGSPICE -b ac_sim.cir
$NGSPICE -b tran_sim.cir