From 5cf331ae8c8a27d4d5c891d912671b6446059998 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Sat, 20 Aug 2016 17:56:41 -0400
Subject: [PATCH] Rewrite WaveTrack::GetEnvelopeValues, taking one less
 argument...

... In practice this argument was always 1 / rate so it was superfluous.

Also make the buffer size argument unsigned.
---
 src/Mix.cpp       | 12 ++++++------
 src/WaveTrack.cpp | 28 +++++++++++++---------------
 src/WaveTrack.h   |  4 ++--
 3 files changed, 21 insertions(+), 23 deletions(-)

diff --git a/src/Mix.cpp b/src/Mix.cpp
index 329afc81d..638808b16 100644
--- a/src/Mix.cpp
+++ b/src/Mix.cpp
@@ -460,8 +460,7 @@ sampleCount Mixer::MixVariableRates(int *channelFlags, WaveTrackCache &cache,
 
                track->GetEnvelopeValues(mEnvValues,
                                         getLen,
-                                        (*pos - (getLen- 1)) / trackRate,
-                                        tstep);
+                                        (*pos - (getLen- 1)) / trackRate);
 
                *pos -= getLen;
             }
@@ -471,8 +470,7 @@ sampleCount Mixer::MixVariableRates(int *channelFlags, WaveTrackCache &cache,
 
                track->GetEnvelopeValues(mEnvValues,
                                         getLen,
-                                        (*pos) / trackRate,
-                                        tstep);
+                                        (*pos) / trackRate);
 
                *pos += getLen;
             }
@@ -584,10 +582,12 @@ sampleCount Mixer::MixSameRate(int *channelFlags, WaveTrackCache &cache,
    if (slen > mMaxOut)
       slen = mMaxOut;
 
+   wxASSERT(slen >= 0);
+
    if (backwards) {
       auto results = cache.Get(floatSample, *pos - (slen - 1), slen);
       memcpy(mFloatBuffer, results, sizeof(float) * slen);
-      track->GetEnvelopeValues(mEnvValues, slen, t - (slen - 1) / mRate, 1.0 / mRate);
+      track->GetEnvelopeValues(mEnvValues, slen, t - (slen - 1) / mRate);
       for(int i=0; i<slen; i++)
          mFloatBuffer[i] *= mEnvValues[i]; // Track gain control will go here?
       ReverseSamples((samplePtr)mFloatBuffer, floatSample, 0, slen);
@@ -597,7 +597,7 @@ sampleCount Mixer::MixSameRate(int *channelFlags, WaveTrackCache &cache,
    else {
       auto results = cache.Get(floatSample, *pos, slen);
       memcpy(mFloatBuffer, results, sizeof(float) * slen);
-      track->GetEnvelopeValues(mEnvValues, slen, t, 1.0 / mRate);
+      track->GetEnvelopeValues(mEnvValues, slen, t);
       for(int i=0; i<slen; i++)
          mFloatBuffer[i] *= mEnvValues[i]; // Track gain control will go here?
 
diff --git a/src/WaveTrack.cpp b/src/WaveTrack.cpp
index e47acbc43..341e87776 100644
--- a/src/WaveTrack.cpp
+++ b/src/WaveTrack.cpp
@@ -2096,13 +2096,9 @@ bool WaveTrack::Set(samplePtr buffer, sampleFormat format,
    return result;
 }
 
-void WaveTrack::GetEnvelopeValues(double *buffer, int bufferLen,
-                         double t0, double tstep) const
+void WaveTrack::GetEnvelopeValues(double *buffer, size_t bufferLen,
+                                  double t0) const
 {
-   // Possibly nothing to do.
-   if( bufferLen <= 0 )
-      return;
-
    // The output buffer corresponds to an unbroken span of time which the callers expect
    // to be fully valid.  As clips are processed below, the output buffer is updated with
    // envelope values from any portion of a clip, start, end, middle, or none at all.
@@ -2119,29 +2115,31 @@ void WaveTrack::GetEnvelopeValues(double *buffer, int bufferLen,
    }
 
    double startTime = t0;
-   double endTime = t0+tstep*bufferLen;
+   auto tstep = 1.0 / mRate;
+   double endTime = t0 + tstep * bufferLen;
    for (const auto &clip: mClips)
    {
       // IF clip intersects startTime..endTime THEN...
-      double dClipStartTime = clip->GetStartTime();
-      double dClipEndTime = clip->GetEndTime();
+      auto dClipStartTime = clip->GetStartTime();
+      auto dClipEndTime = clip->GetEndTime();
       if ((dClipStartTime < endTime) && (dClipEndTime > startTime))
       {
-         double* rbuf = buffer;
-         int rlen = bufferLen;
-         double rt0 = t0;
+         auto rbuf = buffer;
+         auto rlen = bufferLen;
+         auto rt0 = t0;
 
          if (rt0 < dClipStartTime)
          {
             sampleCount nDiff = (sampleCount)floor((dClipStartTime - rt0) * mRate + 0.5);
             rbuf += nDiff;
+            wxASSERT(nDiff <= rlen);
             rlen -= nDiff;
             rt0 = dClipStartTime;
          }
 
          if (rt0 + rlen*tstep > dClipEndTime)
          {
-            int nClipLen = clip->GetEndSample() - clip->GetStartSample();
+            auto nClipLen = clip->GetEndSample() - clip->GetStartSample();
 
             if (nClipLen <= 0) // Testing for bug 641, this problem is consistently '== 0', but doesn't hurt to check <.
                return;
@@ -2151,8 +2149,8 @@ void WaveTrack::GetEnvelopeValues(double *buffer, int bufferLen,
             // This conditional prevents the previous write past the buffer end, in clip->GetEnvelope() call.
             // Never increase rlen here.
             // PRL bug 827:  rewrote it again
-            rlen = std::min(rlen, nClipLen);
-            rlen = std::min(rlen, int(floor(0.5 + (dClipEndTime - rt0) / tstep)));
+            rlen = static_cast<size_t>( std::min(sampleCount( rlen ), nClipLen) );
+            rlen = std::min(rlen, size_t(floor(0.5 + (dClipEndTime - rt0) / tstep)));
          }
          clip->GetEnvelope()->GetValues(rbuf, rlen, rt0, tstep);
       }
diff --git a/src/WaveTrack.h b/src/WaveTrack.h
index ad35eaa98..88ff55adf 100644
--- a/src/WaveTrack.h
+++ b/src/WaveTrack.h
@@ -239,8 +239,8 @@ class AUDACITY_DLL_API WaveTrack final : public Track {
                    sampleCount start, sampleCount len, fillFormat fill=fillZero) const;
    bool Set(samplePtr buffer, sampleFormat format,
                    sampleCount start, sampleCount len);
-   void GetEnvelopeValues(double *buffer, int bufferLen,
-                         double t0, double tstep) const;
+   void GetEnvelopeValues(double *buffer, size_t bufferLen,
+                         double t0) const;
    bool GetMinMax(float *min, float *max,
                   double t0, double t1) const;
    bool GetRMS(float *rms, double t0, double t1);