AudioUnitUtils.cpp

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/*!********************************************************************
 
  Audacity: A Digital Audio Editor
 
  @file AudioUnitUtils.cpp
 
  Paul Licameli
 
***********************************************************************/
 
#include "AudioUnitUtils.h"
#include "MemoryX.h"
 
OSStatus AudioUnitUtils::GetFixedSizePropertyPtr(AudioUnit unit,
   AudioUnitPropertyID inID, void *pProperty, const UInt32 size,
   AudioUnitScope inScope, AudioUnitElement inElement)
{
   auto newSize = size;
   auto result = AudioUnitGetProperty(unit, inID, inScope, inElement,
      pProperty, &newSize);
   assert(newSize <= size);
   return result;
}
 
OSStatus AudioUnitUtils::GetVariableSizePropertyPtr(AudioUnit unit,
   AudioUnitPropertyID inID, const size_t minSize,
   void *&pObject, size_t &size,
   AudioUnitScope inScope, AudioUnitElement inElement)
{
   size = 0;
 
   // Query for statically unknown size of the property first
   UInt32 dataSize;
   auto result = AudioUnitGetPropertyInfo(unit, inID, inScope, inElement,
      &dataSize, nullptr);
   if (result)
      return result;
 
   // Allocate
   auto newSize = std::max<size_t>(minSize, dataSize);
   auto pObj = ::operator new(newSize);
   auto cleanup = finally([&]{
      // In case AudioUnitGetProperty fails
      if (!pObject)
         ::operator delete(pObj);
   });
 
   // Try to get the property
   dataSize = newSize;
   result =
      AudioUnitGetProperty(unit, inID, inScope, inElement, pObj, &dataSize);
   if (result) {
      pObject = nullptr;
      return result;
   }
 
   // Success
   pObject = pObj;
   size = newSize;
   return result;
}
 
OSStatus AudioUnitUtils::SetPropertyPtr(AudioUnit unit,
   AudioUnitPropertyID inID, const void *pProperty, UInt32 size,
   AudioUnitScope inScope, AudioUnitElement inElement)
{
   return AudioUnitSetProperty(unit, inID, inScope, inElement,
      pProperty, size);
}