move scheduler to core + move audioctx to userland

packages/core/scheduler.mjs

@@ -0,0 +1,50 @@
+/*
+scheduler.mjs - <short description TODO>
+Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/scheduler.mjs>
+This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+import { ClockWorker } from './clockworker.mjs';
+
+export class Scheduler {
+  worker;
+  pattern;
+  phase;
+  cps = 1;
+  constructor({ interval = 0.1, onTrigger, latency = 0.1 }) {
+    this.worker = new ClockWorker((_, interval) => {
+      const begin = this.phase;
+      const end = this.phase + interval * this.cps;
+      this.phase = end;
+      const haps = this.pattern.queryArc(begin, end);
+      haps.forEach((hap) => {
+        if (typeof hap.value?.cps === 'number') {
+          this.setCps(hap.value?.cps);
+        }
+        if (!hap.part.begin.equals(hap.whole.begin)) {
+          return;
+        }
+        const deadline = (hap.whole.begin - begin) / this.cps + latency;
+        // TODO: use legato / duration of objectified value
+        const duration = hap.duration / this.cps;
+        onTrigger?.(hap, deadline, duration);
+      });
+    }, interval);
+  }
+  start() {
+    if (!this.pattern) {
+      throw new Error('Scheduler: no pattern set! call .setPattern first.');
+    }
+    this.phase = 0;
+    this.worker.start();
+  }
+  stop() {
+    this.worker.stop();
+  }
+  setPattern(pat) {
+    this.pattern = pat;
+  }
+  setCps(cps = 1) {
+    this.cps = cps;
+  }
+}