Promote simple const variables to constexpr

23 files changed, 34 insertions, 35 deletions

diff --git a/src/engine/bufferscalers/enginebufferscalelinear.h b/src/engine/bufferscalers/enginebufferscalelinear.h
index a27c11f7be..4d7b989c29 100644
--- a/src/engine/bufferscalers/enginebufferscalelinear.h
+++ b/src/engine/bufferscalers/enginebufferscalelinear.h
@@ -4,7 +4,7 @@
 #include "engine/readaheadmanager.h"
 
 /** Number of samples to read ahead */
-const int kiLinearScaleReadAheadLength = 10240;
+constexpr int kiLinearScaleReadAheadLength = 10240;
 
 
 class EngineBufferScaleLinear : public EngineBufferScale  {
diff --git a/src/engine/bufferscalers/enginebufferscalerubberband.cpp b/src/engine/bufferscalers/enginebufferscalerubberband.cpp
index e1b5f02542..45bd55ff92 100644
--- a/src/engine/bufferscalers/enginebufferscalerubberband.cpp
+++ b/src/engine/bufferscalers/enginebufferscalerubberband.cpp
@@ -54,7 +54,7 @@ void EngineBufferScaleRubberBand::setScaleParameters(double base_rate,
     // References:
     // https://bugs.launchpad.net/ubuntu/+bug/1263233
     // https://bitbucket.org/breakfastquay/rubberband/issue/4/sigfpe-zero-division-with-high-time-ratios
-    const double kMinSeekSpeed = 1.0 / 128.0;
+    constexpr double kMinSeekSpeed = 1.0 / 128.0;
     double speed_abs = fabs(*pTempoRatio);
     if (speed_abs < kMinSeekSpeed) {
         // Let the caller know we ignored their speed.
diff --git a/src/engine/bufferscalers/enginebufferscalest.cpp b/src/engine/bufferscalers/enginebufferscalest.cpp
index f23aa4b936..b5966a8e96 100644
--- a/src/engine/bufferscalers/enginebufferscalest.cpp
+++ b/src/engine/bufferscalers/enginebufferscalest.cpp
@@ -22,7 +22,7 @@ namespace {
 // 0.918 (upscaling 44.1 kHz to 48 kHz) will produce an additional offset of 3 Frames
 // 0.459 (upscaling 44.1 kHz to 96 kHz) will produce an additional offset of 18 Frames
 // (Rubberband does not suffer this issue)
-const SINT kSeekOffsetFrames = 519;
+constexpr SINT kSeekOffsetFrames = 519;
 
 }  // namespace
 
diff --git a/src/engine/cachingreader/cachingreader.cpp b/src/engine/cachingreader/cachingreader.cpp
index 91a8e940ee..550228a7fa 100644
--- a/src/engine/cachingreader/cachingreader.cpp
+++ b/src/engine/cachingreader/cachingreader.cpp
@@ -20,7 +20,7 @@ mixxx::Logger kLogger("CachingReader");
 // This is the default hint frameCount that is adopted in case of Hint::kFrameCountForward and
 // Hint::kFrameCountBackward count is provided. It matches 23 ms @ 44.1 kHz
 // TODO() Do we suffer cache misses if we use an audio buffer of above 23 ms?
-const SINT kDefaultHintFrames = 1024;
+constexpr SINT kDefaultHintFrames = 1024;
 
 // With CachingReaderChunk::kFrames = 8192 each chunk consumes
 // 8192 frames * 2 channels/frame * 4-bytes per sample = 65 kB.
@@ -37,7 +37,7 @@ const SINT kDefaultHintFrames = 1024;
 // (kNumberOfCachedChunksInMemory = 1, 2, 3, ...) for testing purposes
 // to verify that the MRU/LRU cache works as expected. Even though
 // massive drop outs are expected to occur Mixxx should run reliably!
-const SINT kNumberOfCachedChunksInMemory = 80;
+constexpr SINT kNumberOfCachedChunksInMemory = 80;
 
 } // anonymous namespace
 
diff --git a/src/engine/cachingreader/cachingreaderchunk.cpp b/src/engine/cachingreader/cachingreaderchunk.cpp
index 1ce0a1de0b..fed9aa5272 100644
--- a/src/engine/cachingreader/cachingreaderchunk.cpp
+++ b/src/engine/cachingreader/cachingreaderchunk.cpp
@@ -13,7 +13,7 @@ namespace {
 
 mixxx::Logger kLogger("CachingReaderChunk");
 
-const SINT kInvalidChunkIndex = -1;
+constexpr SINT kInvalidChunkIndex = -1;
 
 } // anonymous namespace
 
diff --git a/src/engine/channelhandle.h b/src/engine/channelhandle.h
index 240e5254f5..1fc1d4abcf 100644
--- a/src/engine/channelhandle.h
+++ b/src/engine/channelhandle.h
@@ -167,7 +167,7 @@ typedef std::shared_ptr<ChannelHandleFactory> ChannelHandleFactoryPointer;
 // integer value.
 template <class T>
 class ChannelHandleMap {
-    static const int kMaxExpectedGroups = 256;
+    static constexpr int kMaxExpectedGroups = 256;
     typedef QVarLengthArray<T, kMaxExpectedGroups> container_type;
   public:
     typedef typename QVarLengthArray<T, kMaxExpectedGroups>::const_iterator const_iterator;
diff --git a/src/engine/controls/bpmcontrol.cpp b/src/engine/controls/bpmcontrol.cpp
index 7c161341f6..ac34068bd6 100644
--- a/src/engine/controls/bpmcontrol.cpp
+++ b/src/engine/controls/bpmcontrol.cpp
@@ -514,16 +514,16 @@ double BpmControl::calcSyncAdjustment(bool userTweakingSync) {
         // Threshold above which sync is really, really bad, so much so that we
         // don't even know if we're ahead or behind.  This can occur when quantize was
         // off, but then it gets turned on.
-        const double kTrainWreckThreshold = 0.2;
-        const double kSyncAdjustmentCap = 0.05;
+        constexpr double kTrainWreckThreshold = 0.2;
+        constexpr double kSyncAdjustmentCap = 0.05;
         if (fabs(error) > kTrainWreckThreshold) {
             // Assume poor reflexes (late button push) -- speed up to catch the other track.
             adjustment = 1.0 + kSyncAdjustmentCap;
         } else if (fabs(error) > kErrorThreshold) {
             // Proportional control constant. The higher this is, the more we
             // influence sync.
-            const double kSyncAdjustmentProportional = 0.7;
-            const double kSyncDeltaCap = 0.02;
+            constexpr double kSyncAdjustmentProportional = 0.7;
+            constexpr double kSyncDeltaCap = 0.02;
 
             // TODO(owilliams): There are a lot of "1.0"s in this code -- can we eliminate them?
             const double adjust = 1.0 + (-error * kSyncAdjustmentProportional);
diff --git a/src/engine/controls/enginecontrol.h b/src/engine/controls/enginecontrol.h
index 753703f07f..d155568a61 100644
--- a/src/engine/controls/enginecontrol.h
+++ b/src/engine/controls/enginecontrol.h
@@ -17,7 +17,7 @@
 class EngineMaster;
 class EngineBuffer;
 
-const int kNoTrigger = -1;
+constexpr int kNoTrigger = -1;
 static_assert(
         mixxx::audio::FramePos::kLegacyInvalidEnginePosition == kNoTrigger,
         "Invalid engine position value mismatch");
diff --git a/src/engine/controls/keycontrol.cpp b/src/engine/controls/keycontrol.cpp
index 874cdf5cb5..01e4fbea6f 100644
--- a/src/engine/controls/keycontrol.cpp
+++ b/src/engine/controls/keycontrol.cpp
@@ -12,8 +12,8 @@
 #include "track/keyutils.h"
 
 //static const double kLockOriginalKey = 0;
-static const double kLockCurrentKey = 1;
-static const double kKeepUnlockedKey = 1;
+static constexpr double kLockCurrentKey = 1;
+static constexpr double kKeepUnlockedKey = 1;
 
 KeyControl::KeyControl(const QString& group,
         UserSettingsPointer pConfig)
diff --git a/src/engine/controls/ratecontrol.cpp b/src/engine/controls/ratecontrol.cpp
index 51716267f8..dc0c3babd9 100644
--- a/src/engine/controls/ratecontrol.cpp
+++ b/src/engine/controls/ratecontrol.cpp
@@ -364,7 +364,7 @@ double RateControl::getWheelFactor() const {
 
 double RateControl::getJogFactor() const {
     // FIXME: Sensitivity should be configurable separately?
-    const double jogSensitivity = 0.1;  // Nudges during playback
+    constexpr double jogSensitivity = 0.1; // Nudges during playback
     double jogValue = m_pJog->get();
 
     // Since m_pJog is an accumulator, reset it since we've used its value.
diff --git a/src/engine/enginemaster.cpp b/src/engine/enginemaster.cpp
index c8267451cb..6995288ad8 100644
--- a/src/engine/enginemaster.cpp
+++ b/src/engine/enginemaster.cpp
@@ -399,7 +399,7 @@ void EngineMaster::process(const int iBufferSize) {
     m_sampleRate = mixxx::audio::SampleRate::fromDouble(m_pMasterSampleRate->get());
     m_iBufferSize = iBufferSize;
     // TODO: remove assumption of stereo buffer
-    const unsigned int kChannels = 2;
+    constexpr unsigned int kChannels = 2;
     const unsigned int iFrames = iBufferSize / kChannels;
 
     if (m_pEngineEffectsManager) {
@@ -825,7 +825,7 @@ void EngineMaster::addChannel(EngineChannel* pChannel) {
     pChannelInfo->m_pBuffer = SampleUtil::alloc(MAX_BUFFER_LEN);
     SampleUtil::clear(pChannelInfo->m_pBuffer, MAX_BUFFER_LEN);
     m_channels.append(pChannelInfo);
-    const GainCache gainCacheDefault = {0, false};
+    constexpr GainCache gainCacheDefault = {0, false};
     m_channelHeadphoneGainCache.append(gainCacheDefault);
     m_channelTalkoverGainCache.append(gainCacheDefault);
     m_channelMasterGainCache.append(gainCacheDefault);
diff --git a/src/engine/enginemaster.h b/src/engine/enginemaster.h
index 7033f9ca2c..badf694c8b 100644
--- a/src/engine/enginemaster.h
+++ b/src/engine/enginemaster.h
@@ -33,7 +33,7 @@ class EngineDelay;
 
 // The number of channels to pre-allocate in various structures in the
 // engine. Prevents memory allocation in EngineMaster::addChannel.
-static const int kPreallocatedChannels = 64;
+static constexpr int kPreallocatedChannels = 64;
 
 class EngineMaster : public QObject, public AudioSource {
     Q_OBJECT
diff --git a/src/engine/enginepregain.cpp b/src/engine/enginepregain.cpp
index e4f1bbb0b0..d8d938560e 100644
--- a/src/engine/enginepregain.cpp
+++ b/src/engine/enginepregain.cpp
@@ -95,7 +95,7 @@ void EnginePregain::process(CSAMPLE* pInOut, const int iBufferSize) {
 
         // This means that a ReplayGain value has been calculated after the
         // track has been loaded
-        const float kFadeSeconds = 1.0;
+        constexpr float kFadeSeconds = 1.0;
 
         if (m_bSmoothFade) {
             float seconds = static_cast<float>(m_timer.elapsed().toDoubleSeconds());
diff --git a/src/engine/filters/enginefiltermoogladder4.h b/src/engine/filters/enginefiltermoogladder4.h
index b1f33c7c70..c6e3bd8a98 100644
--- a/src/engine/filters/enginefiltermoogladder4.h
+++ b/src/engine/filters/enginefiltermoogladder4.h
@@ -73,7 +73,7 @@ class EngineFilterMoogLadderBase : public EngineObjectConstIn {
     // cutoff  in Hz
     // resonance  range 0 ... 4 (4 = self resonance)
     void setParameter(int sampleRate, float cutoff, float resonance) {
-        const float v2 = 2 + kVt;   // twice the 'thermal voltage of a transistor'
+        constexpr float v2 = 2 + kVt; // twice the 'thermal voltage of a transistor'
 
         float kfc = cutoff / sampleRate;
         float kf = kfc;
@@ -182,8 +182,7 @@ class EngineFilterMoogLadderBase : public EngineObjectConstIn {
     }
 
     inline CSAMPLE processSample(float input, struct Buffer* pB) {
-
-        const float v2 = 2 + kVt;   // twice the 'thermal voltage of a transistor'
+        constexpr float v2 = 2 + kVt; // twice the 'thermal voltage of a transistor'
 
         // cascade of 4 1st-order sections
         float x1 = input - pB->m_amf * m_kacr;
diff --git a/src/engine/filters/enginefilterpan.h b/src/engine/filters/enginefilterpan.h
index 30127ea0ce..51ad19c03d 100644
--- a/src/engine/filters/enginefilterpan.h
+++ b/src/engine/filters/enginefilterpan.h
@@ -5,7 +5,7 @@
 #include "engine/engineobject.h"
 #include "util/assert.h"
 
-static const int numChannels = 2;
+static constexpr int numChannels = 2;
 
 template<unsigned int SIZE>
 class EngineFilterPan : public EngineObjectConstIn {
diff --git a/src/engine/filters/enginefilterpansingle.h b/src/engine/filters/enginefilterpansingle.h
index df0a608148..1861b97db8 100644
--- a/src/engine/filters/enginefilterpansingle.h
+++ b/src/engine/filters/enginefilterpansingle.h
@@ -12,7 +12,7 @@
 #include "engine/engineobject.h"
 #include "util/assert.h"
 
-static const int numChannels = 2;
+static constexpr int numChannels = 2;
 
 template<unsigned int SIZE>
 class EngineFilterPanSingle {
diff --git a/src/engine/positionscratchcontroller.cpp b/src/engine/positionscratchcontroller.cpp
index 0edc4a7ac5..e217a8fb73 100644
--- a/src/engine/positionscratchcontroller.cpp
+++ b/src/engine/positionscratchcontroller.cpp
@@ -145,9 +145,9 @@ void PositionScratchController::process(double currentSample, double releaseRate
             }
 
             // Max velocity we would like to stop in a given time period.
-            const double kMaxVelocity = 100;
+            constexpr double kMaxVelocity = 100;
             // Seconds to stop a throw at the max velocity.
-            const double kTimeToStop = 1.0;
+            constexpr double kTimeToStop = 1.0;
 
             // We calculate the exponential decay constant based on the above
             // constants. Roughly we backsolve what the decay should be if we want to
@@ -239,7 +239,7 @@ void PositionScratchController::process(double currentSample, double releaseRate
 
             // The rate threshold above which disabling position scratching will enable
             // an 'inertia' mode.
-            const double kThrowThreshold = 2.5;
+            constexpr double kThrowThreshold = 2.5;
 
             if (fabs(m_dRate) > kThrowThreshold) {
                 m_bEnableInertia = true;
diff --git a/src/engine/readaheadmanager.cpp b/src/engine/readaheadmanager.cpp
index 8958ea44ac..451c00adb1 100644
--- a/src/engine/readaheadmanager.cpp
+++ b/src/engine/readaheadmanager.cpp
@@ -7,7 +7,7 @@
 #include "util/math.h"
 #include "util/sample.h"
 
-static const int kNumChannels = 2;
+static constexpr int kNumChannels = 2;
 
 ReadAheadManager::ReadAheadManager()
         : m_pLoopingControl(nullptr),
diff --git a/src/engine/sidechain/enginenetworkstream.cpp b/src/engine/sidechain/enginenetworkstream.cpp
index 6c8b75c643..bd4c3f1efa 100644
--- a/src/engine/sidechain/enginenetworkstream.cpp
+++ b/src/engine/sidechain/enginenetworkstream.cpp
@@ -19,7 +19,7 @@ static PgGetSystemTimeFn s_pfpgGetSystemTimeFn = NULL;
 #include "util/sample.h"
 
 namespace {
-const int kNetworkLatencyFrames = 8192; // 185 ms @ 44100 Hz
+constexpr int kNetworkLatencyFrames = 8192; // 185 ms @ 44100 Hz
 // Related chunk sizes:
 // Mp3 frames = 1152 samples
 // Ogg frames = 64 to 8192 samples.
diff --git a/src/engine/sidechain/enginerecord.cpp b/src/engine/sidechain/enginerecord.cpp
index a2678a8eed..bb77b5d7ea 100644
--- a/src/engine/sidechain/enginerecord.cpp
+++ b/src/engine/sidechain/enginerecord.cpp
@@ -10,7 +10,7 @@
 #include "track/track.h"
 #include "util/event.h"
 
-const int kMetaDataLifeTimeout = 16;
+constexpr int kMetaDataLifeTimeout = 16;
 
 EngineRecord::EngineRecord(UserSettingsPointer pConfig)
         : m_pConfig(pConfig),
diff --git a/src/engine/sidechain/enginesidechain.cpp b/src/engine/sidechain/enginesidechain.cpp
index 40e2af7a7e..ee930a0fcd 100644
--- a/src/engine/sidechain/enginesidechain.cpp
+++ b/src/engine/sidechain/enginesidechain.cpp
@@ -78,7 +78,7 @@ void EngineSideChain::receiveBuffer(const AudioInput& input,
 void EngineSideChain::writeSamples(const CSAMPLE* pBuffer, int iFrames) {
     Trace sidechain("EngineSideChain::writeSamples");
     // TODO: remove assumption of stereo buffer
-    const int kChannels = 2;
+    constexpr int kChannels = 2;
     const int iSamples = iFrames * kChannels;
     int samples_written = m_sampleFifo.write(pBuffer, iSamples);
 
diff --git a/src/engine/sidechain/enginesidechain.h b/src/engine/sidechain/enginesidechain.h
index 15209e2fdc..5552580aeb 100644
--- a/src/engine/sidechain/enginesidechain.h
+++ b/src/engine/sidechain/enginesidechain.h
@@ -32,7 +32,7 @@ class EngineSideChain : public QThread, public AudioDestination {
     // Thread-safe, blocking.
     void addSideChainWorker(SideChainWorker* pWorker);
 
-    static const int SIDECHAIN_BUFFER_SIZE = 65536;
+    static constexpr int SIDECHAIN_BUFFER_SIZE = 65536;
 
   private:
     void run() override;
diff --git a/src/engine/sidechain/shoutconnection.cpp b/src/engine/sidechain/shoutconnection.cpp
index 768028e5f4..a9c541e872 100644
--- a/src/engine/sidechain/shoutconnection.cpp
+++ b/src/engine/sidechain/shoutconnection.cpp
@@ -33,11 +33,11 @@
 
 namespace {
 
-const int kConnectRetries = 30;
-const int kMaxNetworkCache = 491520;  // 10 s mp3 @ 192 kbit/s
+constexpr int kConnectRetries = 30;
+constexpr int kMaxNetworkCache = 491520; // 10 s mp3 @ 192 kbit/s
 // Shoutcast default receive buffer 1048576 and autodumpsourcetime 30 s
 // http://wiki.shoutcast.com/wiki/SHOUTcast_DNAS_Server_2
-const int kMaxShoutFailures = 3;
+constexpr int kMaxShoutFailures = 3;
 
 const QRegularExpression kArtistOrTitleRegex(QStringLiteral("\\$artist|\\$title"));
 const QRegularExpression kArtistRegex(QStringLiteral("\\$artist"));