From 71fd9e319a51f5d3d49fa4b1c23d08c5ff4d3ab0 Mon Sep 17 00:00:00 2001
From: Mike Lynch <m.lynch@sydney.edu.au>
Date: Wed, 27 Dec 2023 15:16:37 +1100
Subject: [PATCH] Made time calculations all be in integer microseconds

---
 Xmas/Xmas.ino | 71 +++++++++++++++++++++++++++++----------------------
 1 file changed, 40 insertions(+), 31 deletions(-)

diff --git a/Xmas/Xmas.ino b/Xmas/Xmas.ino
index dd24a99..0799ee9 100644
--- a/Xmas/Xmas.ino
+++ b/Xmas/Xmas.ino
@@ -35,7 +35,7 @@ the absolute start time should include a count-in
 
 
 int m1[] =     { 0,    2,    4,   5,     7,   9,  11, 12 };
-int s1[] =     { 0,    3,    5,   7,    9,  11,  13, 15 };
+int s1[] =     { 0,    2,    4,   6,    8,  10,  12,  14 };
 float d1[] =   { 1.0, 0.5, 1.0, 0.5,  1.0, 0.5, 1.0, 0.5  };
 int m2[] =     { 0,    4,    7,  12, 0,    4,    7,  12, 0,    4,    7,  12, 0,    4,    7,  12 };
 int s2[] =     { 0, 1 ,    2,    3,   4,    5,  6,  7, 8, 9, 10, 11, 12, 13, 14, 15 };
@@ -45,12 +45,14 @@ float d2[] =   { 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5, 0.5
 float gate = 0.5;
 int bpm = 180;
 float beat_s = 60.0 / (float)bpm;
-int beat_m = round(1000.0 * beat_s); 
+int beat = round(1000.0 * beat_s); 
 
 // count_in = number of beats since t0 to wait before we startt playing
 // repeat = number of beats to repeat - could be computed from the sequence data
 
-long count_in_m = 4 * beat_m;
+// From here on, all times are in milliseconds to head off floating point errors
+
+long count_in = 4 * beat;
 int repeat = 16;
 
 
@@ -112,31 +114,49 @@ void setup(void) {
   seq2.start = s2;
   seq2.len = sizeof(m2) / sizeof(m2[0]);
 
+  times_to_ms(seq1);
+  times_to_ms(seq2);
+
 }
 
+void times_to_ms(sequencer& seq) {
+  for( int i = 0; i < seq.len; i++ ) {
+    seq.start[i] *= beat;
+    seq.duration[i] = (float)beat * seq.duration[i];
+  }
+}
+
+
 
 void loop() {
   long now = millis();
-  long beat_int = (now - start_time - count_in_m) % (beat_m * repeat);
-  float beat = (float)(beat_int) / (float)beat_m;
-  runSequencer(seq1, now, beat);
-  runSequencer(seq2, now, beat);
+  long t = now - start_time;
+  long beats = -1;
+  if( t >= count_in ) {
+    beats = (t - count_in) % (beat * repeat);
+    runSequencer(seq1, t, beats);
+    runSequencer(seq2, t, beats);
+  }
 }
 
-void runSequencer(sequencer& seq, long now, float beat) {
-  if( seq.s < seq.len - 1 ) {
-    if( beat > (float)seq.start[seq.s + 1] ) {
-      seq.s += 1;
-      seq.rel = now + round((float)beat_m * seq.duration[seq.s]);
-      if( seq.melody[seq.s] > -1 ) {
-        mcp.setChannelValue(seq.pitch, tuning[seq.melody[seq.s]]);
-        mcp.setChannelValue(seq.gate, 4095);
-      }
-      seq.playing = 1;
-      if( seq.s == seq.len - 1 ) {
-        seq.s = -1;
-      }
+void runSequencer(sequencer& seq, long now, long beats) {
+  int next = seq.s + 1;
+  int start;
+  if( next > seq.len - 1 ) {
+    seq.s = -1;
+    next = 0;
+    return; // don't start the loop yet
+  } else {
+    start = seq.start[next];
+  }
+  if( beats >= start ) {
+    seq.s = next;
+    seq.rel = now + seq.duration[seq.s];
+    if( seq.melody[seq.s] > -1 ) {
+      mcp.setChannelValue(seq.pitch, tuning[seq.melody[seq.s]]);
+      mcp.setChannelValue(seq.gate, 4095);
     }
+    seq.playing = 1;
   }
   if( seq.playing ) {
     if( now > seq.rel ) {
@@ -146,14 +166,3 @@ void runSequencer(sequencer& seq, long now, float beat) {
   }
 }
 
-
-// void noteOn(sequencer& seq, int note) {
-//   if( note > -1 ) {
-//     mcp.setChannelValue(seq.pitch, tuning[note]);
-//     mcp.setChannelValue(seq.gate, 4095);
-//   }
-// }
-
-// void noteOff(sequencer& seq) {
-//     mcp.setChannelValue(seq.gate, 0);
-// }