NetlistParser

SPICE netlist in, placed schematic out: devices at integer points with an orientation, every pin's point, wires as polylines per net, junction dots, net labels and no-connect marks laid out the way textbooks draw circuits (supply at the top, ground at the bottom, signal left to right).

The library draws nothing and knows no device. The application says what each device class looks like (terminal anchors and body strokes) and reads the result to write its own format. Its public boundaries follow cktImg's; see docs/API.md.

const np = @import("NetlistParser");

var lib = np.Library.init(gpa);                 // your symbols
defer lib.deinit();
try lib.loadZon(arena, symbols_zon, &diags);    // e.g. tests/symbols.zon

var placed = try np.place(gpa, &np.Config.default, &lib, &.{spice_text}, &diag);
defer placed.deinit();
// placed.dev_pos, .dev_orient, .pin_xy, .segments(net), .junctions, .labels, …

Examples

Drawn by the library, untouched, with the tests' symbol set (zig build gallery -- --svgs out/ makes all of them).

Bandgap reference. Three mirrored PMOS branches and an op-amp between the first two. The shared gate line g is labelled, because wiring it would have to cross the branches.

Telescopic cascode OTA. Two stacked columns of five transistors that stay level, with bias lines as labels.

Two-stage Miller op-amp. Mirror load, tail source, second stage and the compensation capacitor across it.

Five-transistor OTA.

Sallen-Key low-pass with a unity-gain buffer. The feedback capacitor's far end is named out rather than routed around the op-amp.

Differential pair with resistive loads.

A .subckt as a block. It's the op-amp below, drawn with its ports placed as the *@ comments say.

Subcircuits

An X instance of a .subckt in the netlist is one block, drawn with your class of that name or a generated box. Comments in the definition steer it:

.subckt opamp inp inn out vdd vss
*@ left inp inn        (also right / top / bottom)
*@ right out
...
.ends

*@ expand draws the body instead, flattened with ngspice names (r.x1.r1).

Build

Zig 0.16.0.

zig build                             # libcktimg.a + include/cktimg.h + the gallery tool
zig build test                        # library, algorithm, API and C ABI tests
zig build -Dlatex_renderer=true       # also cktimg-tex and the TikZ emitter
zig build gallery -- --svgs out/      # the textbook circuits as SVG
zig build gallery -- --config lint.zon in.cir out.svg
zig build fuzz                        # 4000 random netlists; smallest example per rare case

Layout

• src/ — the library: netlist.zig (parser), schematic.zig and layout.zig (the algorithm, specified in ALGORITHM.md), placed.zig (the result), library.zig (device classes), config.zig (lint.zon), lint.zig, geom.zig, latex.zig, json.zig, abi.zig (the C ABI).
• include/cktimg.h — the C header.
• tests/ — the tests, the tests' symbol set (symbols.zon), an SVG renderer and the gallery, all on the public API.
• tools/tex.zig — cktimg-tex, which writes CircuiTikZ; latex/cktimg.sty — the LaTeX package (loads circuitikz).
• tools/xschem/ — the xschem target: cktimg-xschem in.cir out.sch, its symbol set and mapping (symbols.zon, xschem.zon, regenerated from xschem's library by gen_symbols.py), and roundtrip.py, which checks that xschem netlists the drawing back to the input's nets.
• lint.zon — every setting, with its default.