From 4b9e46f11de1a4f6a9c4d17968098ed34f25edeb Mon Sep 17 00:00:00 2001
From: Hector Martin <marcan@marcan.st>
Date: Fri, 13 Nov 2020 02:27:09 +0900
Subject: [PATCH] Fix normalization in Temporal::Beats for times between -1 and
 0 beats

Also fix normalization of times with negative beats and positive ticks
---
 libs/temporal/temporal/beats.h | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/libs/temporal/temporal/beats.h b/libs/temporal/temporal/beats.h
index a7c8696db3..757f0c8771 100644
--- a/libs/temporal/temporal/beats.h
+++ b/libs/temporal/temporal/beats.h
@@ -19,6 +19,7 @@
 #ifndef TEMPORAL_BEATS_HPP
 #define TEMPORAL_BEATS_HPP
 
+#include <cassert>
 #include <float.h>
 #include <math.h>
 #include <stdint.h>
@@ -42,15 +43,21 @@ public:
 	/** Normalize so ticks is within PPQN. */
 	void normalize() {
 		// First, fix negative ticks with positive beats
-		if (_beats >= 0) {
-			while (_ticks < 0) {
-				--_beats;
-				_ticks += PPQN;
-			}
+		while (_beats > 0 && _ticks < 0) {
+			--_beats;
+			_ticks += PPQN;
 		}
 
+		// Now fix positive ticks with negative beats
+		while (_beats < 0 && _ticks > 0) {
+			++_beats;
+			_ticks -= PPQN;
+		}
+
+		assert ((_beats < 0 && _ticks <= 0) || (_beats > 0 && _ticks >= 0) || _beats == 0);
+
 		// Work with positive beats and ticks to normalize
-		const int32_t sign  = _beats < 0 ? -1 : 1;
+		const int32_t sign  = _beats < 0 ? -1 : _ticks < 0 ? -1 : 1;
 		int32_t       beats = abs(_beats);
 		int32_t       ticks = abs(_ticks);