From 67a98234345468da1c768a78c12b7e14c1d80129 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Sat, 11 Aug 2018 23:41:45 -0400
Subject: [PATCH] split out function AdvancedTrackTime; more caution about
 termination

---
 src/AudioIO.cpp | 36 ++++++++++++++++++++++--------------
 src/AudioIO.h   |  7 +++++++
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/src/AudioIO.cpp b/src/AudioIO.cpp
index 05422afec..64713bf37 100644
--- a/src/AudioIO.cpp
+++ b/src/AudioIO.cpp
@@ -5646,23 +5646,18 @@ bool AudioIO::PlaybackSchedule::Overruns( double trackTime ) const
    return (ReversedTime() ? trackTime <= mT1 : trackTime >= mT1);
 }
 
-void AudioIO::PlaybackSchedule::TrackTimeUpdate(double realElapsed)
+double AudioIO::PlaybackSchedule::AdvancedTrackTime(
+   double time, double realElapsed, double speed ) const
 {
-   // Update mTime within the PortAudio callback
-
-   if (Interactive())
-      return;
-
    if (ReversedTime())
       realElapsed *= -1.0;
 
-   auto time = GetTrackTime();
+   // Defense against cases that might cause loops not to terminate
+   if ( fabs(mT0 - mT1) < 1e-9 )
+      return mT0;
+
    if (mTimeTrack) {
-      // Defense against a case that might cause the do-loop not to terminate
-      if ( fabs(mT0 - mT1) < 1e-9 ) {
-         SetTrackTime( mT0 );
-         return;
-      }
+       wxASSERT( speed == 1.0 );
 
       double total;
       bool foundTotal = false;
@@ -5693,7 +5688,7 @@ void AudioIO::PlaybackSchedule::TrackTimeUpdate(double realElapsed)
       } while ( true );
    }
    else {
-      time += realElapsed;
+      time += realElapsed * speed;
 
       // Wrap to start if looping
       if (Looping()) {
@@ -5705,7 +5700,20 @@ void AudioIO::PlaybackSchedule::TrackTimeUpdate(double realElapsed)
          }
       }
    }
-   SetTrackTime( time );
+
+   return time;
+}
+
+void AudioIO::PlaybackSchedule::TrackTimeUpdate(double realElapsed)
+{
+   // Update mTime within the PortAudio callback
+
+   if (Interactive())
+      return;
+
+   auto time = GetTrackTime();
+   auto newTime = AdvancedTrackTime( time, realElapsed, 1.0 );
+   SetTrackTime( newTime );
 }
 
 double AudioIO::PlaybackSchedule::TrackDuration(double realElapsed) const
diff --git a/src/AudioIO.h b/src/AudioIO.h
index c0e684354..7d211e951 100644
--- a/src/AudioIO.h
+++ b/src/AudioIO.h
@@ -954,6 +954,13 @@ private:
       // Returns true if time equals t1 or is on opposite side of t1, to t0
       bool Overruns( double trackTime ) const;
 
+      // Compute the NEW track time for the given one and a real duration,
+      // taking into account whether the schedule is for looping
+      double AdvancedTrackTime(
+         double trackTime, double realElapsed, double speed) const;
+
+      // Use the function above in the callback after consuming samples from the
+      // playback ring buffers, during usual straight or looping play
       void TrackTimeUpdate(double realElapsed);
 
       // Convert a nonnegative real duration to an increment of track time