Add constant twoPiDouble/twoPiFloat to MathExtras.h

Source/platform/audio/DynamicsCompressorKernel.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 276 matching lines @@
 
         // Fix gremlins.
         if (std::isnan(m_detectorAverage))
             m_detectorAverage = 1;
         if (std::isinf(m_detectorAverage))
             m_detectorAverage = 1;
 
         float desiredGain = m_detectorAverage;
 
         // Pre-warp so we get desiredGain after sin() warp below.
-        float scaledDesiredGain = asinf(desiredGain) / (0.5f * piFloat);
+        float scaledDesiredGain = asinf(desiredGain) / (piOverTwoFloat);
 
         // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         // Deal with envelopes
         // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
         // envelopeRate is the rate we slew from current compressor level to the desired level.
         // The exact rate depends on if we're attacking or releasing and by how much.
         float envelopeRate;
 
         bool isReleasing = scaledDesiredGain > m_compressorGain;
@@ skipping 111 matching lines @@
                 if (envelopeRate < 1) {
                     // Attack - reduce gain to desired.
                     compressorGain += (scaledDesiredGain - compressorGain) * envelopeRate;
                 } else {
                     // Release - exponentially increase gain to 1.0
                     compressorGain *= envelopeRate;
                     compressorGain = min(1.0f, compressorGain);
                 }
 
                 // Warp pre-compression gain to smooth out sharp exponential transition points.
-                float postWarpCompressorGain = sinf(0.5f * piFloat * compressorGain);
+                float postWarpCompressorGain = sinf(piOverTwoFloat * compressorGain);
 
                 // Calculate total gain using master gain and effect blend.
                 float totalGain = dryMix + wetMix * masterLinearGain * postWarpCompressorGain;
 
                 // Calculate metering.
                 float dbRealGain = 20 * log10(postWarpCompressorGain);
                 if (dbRealGain < m_meteringGain)
                     m_meteringGain = dbRealGain;
                 else
                     m_meteringGain += (dbRealGain - m_meteringGain) * m_meteringReleaseK;
@@ skipping 30 matching lines @@
 
     m_preDelayReadIndex = 0;
     m_preDelayWriteIndex = DefaultPreDelayFrames;
 
     m_maxAttackCompressionDiffDb = -1; // uninitialized state
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)