add superdough package

packages/superdough/util.mjs

@@ -0,0 +1,29 @@
+// currently duplicate with core util.mjs to skip dependency
+// TODO: add separate util module?
+
+export const tokenizeNote = (note) => {
+  if (typeof note !== 'string') {
+    return [];
+  }
+  const [pc, acc = '', oct] = note.match(/^([a-gA-G])([#bsf]*)([0-9]*)$/)?.slice(1) || [];
+  if (!pc) {
+    return [];
+  }
+  return [pc, acc, oct ? Number(oct) : undefined];
+};
+const chromas = { c: 0, d: 2, e: 4, f: 5, g: 7, a: 9, b: 11 };
+const accs = { '#': 1, b: -1, s: 1, f: -1 };
+
+export const noteToMidi = (note, defaultOctave = 3) => {
+  const [pc, acc, oct = defaultOctave] = tokenizeNote(note);
+  if (!pc) {
+    throw new Error('not a note: "' + note + '"');
+  }
+  const chroma = chromas[pc.toLowerCase()];
+  const offset = acc?.split('').reduce((o, char) => o + accs[char], 0) || 0;
+  return (Number(oct) + 1) * 12 + chroma + offset;
+};
+export const midiToFreq = (n) => {
+  return Math.pow(2, (n - 69) / 12) * 440;
+};
+export const clamp = (num, min, max) => Math.min(Math.max(num, min), max);