danzig-minimal

danzig-minimal

The smallest complete danzig plugin. Copy this to start your own.

What it demonstrates

One file, about 120 lines, most of them comments. It shows the four pieces every danzig plugin needs and nothing else.

A parameter store. danzig.ParamStore(1) holds one trim control spanning -24 to +24 dB with a 20 ms one-pole smoother. The store is a fixed array of cache-line-sized atomic slots, so registering a parameter allocates nothing and reading one from the audio thread cannot block.

A writer path. setParameter does a single atomic store. This is what the host or the UI calls, on its own thread, at any time.

An audio callback. process reads the smoothed value once per sample with tick, converts it to a linear gain, and multiplies. No allocation, no locks, no branches on parameter state. Per-sample smoothing is what stops a slider drag from clicking.

The VST3 entry point. export fn GetPluginFactory() is the only symbol a host looks for in the binary. Here it returns null, which a host reads as "this binary exports no classes". See ../danzig-gain for a factory with a vtable behind it.

The same source builds twice: as the shared library a host would load, and as an executable, so the DSP can be run and checked without a DAW.

Build and run

From the repository root:

zig build run-minimal

danzig-minimal: one parameter, one line of DSP

Trim range is -24 to +24 dB, 20 ms smoothing, 48 kHz.

  full cut     normalized 0.00  ->   -24.00 dB  (output 0.0631)
  unity        normalized 0.50  ->     0.00 dB  (output 1.0000)
  full boost   normalized 1.00  ->    24.00 dB  (output 15.8473)

Copy examples/danzig-minimal/root.zig to start your own plugin.

The demo feeds 500 ms of full-scale DC through the plugin at three trim settings and reads the level off the last sample. DC makes the gain readable directly. 500 ms is well past the 20 ms smoother's settling time, which is why the numbers land on exactly -24, 0, and +24 dB.

Artifacts

zig build
ls zig-out/lib/libDanzigMinimal.dylib zig-out/bin/danzig-minimal

zig-out/bin/danzig-minimal
zig-out/lib/libDanzigMinimal.dylib

libDanzigMinimal.dylib is the plugin. danzig-minimal is the offline demo above.

Starting your own plugin

mkdir -p examples/my-plugin
cp examples/danzig-minimal/root.zig examples/my-plugin/root.zig

Then add it to build.zig next to the danzig_minimal block, changing the names:

const my_plugin = b.addLibrary(.{
    .name = "MyPlugin",
    .root_module = b.createModule(.{
        .root_source_file = b.path("examples/my-plugin/root.zig"),
        .target = target,
        .optimize = optimize,
    }),
    .linkage = .dynamic,
});
my_plugin.root_module.addImport("danzig", danzig_module);
my_plugin.linkLibrary(danzig_lib);
b.installArtifact(my_plugin);

Edit process. Add parameters by widening ParamStore(1) and calling add once more in init.

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See docs/WIKI.md for the parameter system and the audio callback path in full.