From 56fae7e54d43ef76885ba9e496862cd9b702c92a Mon Sep 17 00:00:00 2001
From: Mike Lynch <m.lynch@sydney.edu.au>
Date: Wed, 27 Dec 2023 15:32:04 +1100
Subject: [PATCH] Looping playback works with a basic two-part phrase

---
 Xmas/Xmas.ino | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/Xmas/Xmas.ino b/Xmas/Xmas.ino
index 0799ee9..2ecb4a3 100644
--- a/Xmas/Xmas.ino
+++ b/Xmas/Xmas.ino
@@ -62,7 +62,8 @@ float mod_b = 3.141592653589793 / 4.0;
 
 typedef struct {
   int s = -1;
-  int playing = 0;
+  bool playing = false;
+  bool looped = false;
   long play = 0;
   long rel = 0;
   long last = 0;
@@ -142,13 +143,33 @@ void loop() {
 void runSequencer(sequencer& seq, long now, long beats) {
   int next = seq.s + 1;
   int start;
+
+  if( seq.playing ) {
+    if( now > seq.rel ) {
+      mcp.setChannelValue(seq.gate, 0);
+      seq.playing = false;
+    }
+  }
+
   if( next > seq.len - 1 ) {
     seq.s = -1;
-    next = 0;
+    seq.looped = true;
     return; // don't start the loop yet
   } else {
     start = seq.start[next];
   }
+
+  if( seq.looped ) { // reached the end and waiting for the start of the bar
+    if( beats < seq.last ) {
+      seq.looped = false; // bar has restarted, start waiting
+      seq.s = -1;
+      next = 0;
+    } else {
+      return;
+    }
+  }
+  seq.last = beats;
+
   if( beats >= start ) {
     seq.s = next;
     seq.rel = now + seq.duration[seq.s];
@@ -156,13 +177,7 @@ void runSequencer(sequencer& seq, long now, long beats) {
       mcp.setChannelValue(seq.pitch, tuning[seq.melody[seq.s]]);
       mcp.setChannelValue(seq.gate, 4095);
     }
-    seq.playing = 1;
-  }
-  if( seq.playing ) {
-    if( now > seq.rel ) {
-      mcp.setChannelValue(seq.gate, 0);
-      seq.playing = 0;
-    }
+    seq.playing = true;
   }
 }