Schemify
Introduction

What is Schemify?

Schemify is an open-source schematic editor written in Zig. It targets mixed-signal IC design workflows where analog schematics need to coexist with digital RTL blocks synthesized from Verilog.

Goals

  • XSchem compatibility — read and write .sch / .sym files directly so existing projects migrate without manual conversion.
  • Netlist generation — produce correct ngspice and Xyce SPICE netlists from a schematic, with a comptime device dispatch system that carries no runtime vtable cost.
  • Digital co-simulation — digital blocks embedded in a schematic are compiled with Verilator or synthesized with Yosys as part of the normal simulation flow.
  • Extensible — a stable plugin interface (PluginIF.zig) lets you add devices, themes, and simulation back-ends without forking the repository.
  • Web deployment — zig build -Dbackend=web ships the full editor running in a browser via HTML5 Canvas.

Architecture Overview

src/
  main.zig          ← application entry point (only the 4 dvui callbacks)
  _dvuiIF.zig       ← dvui contract wiring
  state.zig         ← process-lifetime AppState (config, open schematics, history)
  command.zig       ← Command union + undo/redo History
  PluginIF.zig      ← stable public API for plugins
  toml.zig          ← Config.toml parser
  core/
    FileIO.zig      ← schematic I/O (XSchem ↔ CHN conversion)
    devices/        ← comptime device system + netlist emission
    xschem/         ← XSchem reader / writer / types
    chn/            ← CHN reader / writer / types
  gui/              ← dvui rendering layer

Prior Work

Schemify builds on ideas from XSchem by Stefan Schippers and is designed to integrate naturally with the SKY130 and GF180 open PDKs.

Design Principles

Data-oriented design. Schemify uses std.MultiArrayList (Structure-of-Arrays) for schematic data — iterating all X coordinates of wires touches contiguous memory, not a stride through full structs.

Command queue pattern. All mutations go through a Command union. Undo records command inverses, not full snapshots. The command queue drains once per frame — clean separation between input, mutation, and render.

Comptime device dispatch. The device system uses Zig's comptime to generate device-specific netlist emission with zero runtime vtable overhead.

Dual backend. The same source compiles to a native binary (raylib/OpenGL) or a WASM module (HTML5 Canvas). The backend is a compile-time switch.