galdr 0.1.0: terminal grid synthesizer (MIDI in, PipeWire out)

Signal flows downward through single-glyph unit generators; each MIDI note
voices the whole grid; the mix renders low-latency to PipeWire (reusing the
native path from spectrust). Grid edits recompile and hot-swap without
dropping audio. Pairs with orca (note/CC source) and spectrust (visualizer).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GLUwWE2KmFPzhKaf67tWbx

src/midi.rs

@@ -0,0 +1,41 @@
+//! MIDI input. galdr owns a virtual input port named "galdr" (symmetric with
+//! orca's virtual output), so orca or any client connects to it in the graph.
+
+use anyhow::{anyhow, Result};
+use midir::os::unix::VirtualInput;
+use midir::{MidiInput, MidiInputConnection};
+use rtrb::Producer;
+
+use crate::engine::Event;
+
+pub fn connect(prod: Producer<Event>, port_name: Option<String>) -> Result<MidiInputConnection<Producer<Event>>> {
+    let mut input = MidiInput::new("galdr").map_err(|e| anyhow!("MIDI init: {e}"))?;
+    input.ignore(midir::Ignore::None);
+
+    let cb = move |_stamp: u64, msg: &[u8], prod: &mut Producer<Event>| {
+        if msg.len() < 2 {
+            return;
+        }
+        let status = msg[0] & 0xF0;
+        let ev = match status {
+            0x90 if msg[2] > 0 => Event::NoteOn { note: msg[1], vel: msg[2] },
+            0x80 => Event::NoteOff { note: msg[1] },
+            0x90 => Event::NoteOff { note: msg[1] }, // note-on velocity 0
+            0xB0 => Event::Cc { idx: msg[1], val: msg[2] },
+            _ => return,
+        };
+        let _ = prod.push(ev);
+    };
+
+    if let Some(name) = port_name {
+        let ports = input.ports();
+        let port = ports
+            .iter()
+            .find(|p| input.port_name(p).map(|n| n.contains(&name)).unwrap_or(false))
+            .cloned()
+            .ok_or_else(|| anyhow!("no MIDI input port matching {name:?}"))?;
+        input.connect(&port, "galdr-in", cb, prod).map_err(|e| anyhow!("MIDI connect: {e}"))
+    } else {
+        input.create_virtual("galdr", cb, prod).map_err(|e| anyhow!("create virtual MIDI port: {e}"))
+    }
+}