StandardAllocator.h

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//     ____   ______ __
//    / __ \ / ____// /
//   / /_/ // /    / /
//  / ____// /___ / /___   PixInsight Class Library
// /_/     \____//_____/   PCL 2.7.0
// ----------------------------------------------------------------------------
// pcl/StandardAllocator.h - Released 2024-06-18T15:48:54Z
// ----------------------------------------------------------------------------
// This file is part of the PixInsight Class Library (PCL).
// PCL is a multiplatform C++ framework for development of PixInsight modules.
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// ----------------------------------------------------------------------------
 
#ifndef __PCL_StandardAllocator_h
#define __PCL_StandardAllocator_h
 
 
#include <pcl/Defs.h>
#include <pcl/Diagnostics.h>
 
#include <new>
 
namespace pcl
{
 
// ----------------------------------------------------------------------------
 
class PCL_CLASS StandardAllocator
{
public:
 
   StandardAllocator( bool fastGrowth = true, bool canShrink = true )
      : m_fastGrowth( fastGrowth )
      , m_canShrink( canShrink )
   {
   }
 
   StandardAllocator( const StandardAllocator& ) = default;
 
   size_type MaxSize() const
   {
      return ~size_type( 0 );
   }
 
   size_type BlockSize( size_type n ) const
   {
      // Check for null allocation attempts.
      if ( n == 0 )
         return 0;
 
      // Take into account a reasonable upper limit for the size in bytes of an
      // allocation block header.
      const size_type blockHeaderSize = 4*sizeof( void* );
      n += blockHeaderSize;
 
      // Grow linearly by 8-byte chunks for n < 64 bytes.
      if ( n < 64 )
         return ((n >> 3) << 3) + 8 - blockHeaderSize;
 
      // Grow exponentially by doubling container capacity if fast growing is
      // enabled or n < 64 KiB.
      if ( IsFastGrowthEnabled() || n < 65536 )
      {
         size_type nn = 64;
         while ( nn < n )
            nn <<= 1;
         return nn - blockHeaderSize;
      }
 
      // If fast growing is disabled or n >= 64 KiB, grow linearly by 4 KiB
      // chunks.
      return ((n >> 12) << 12) + 4096 - blockHeaderSize;
   }
 
   size_type ReallocatedBlockSize( size_type currentSize, size_type newSize ) const
   {
      return (currentSize < newSize || m_canShrink) ? BlockSize( newSize ) : currentSize;
   }
 
   void* AllocateBlock( size_type size )
   {
      PCL_PRECONDITION( size != 0 )
      return ::operator new( size );
   }
 
   void DeallocateBlock( void* p )
   {
      PCL_PRECONDITION( p != nullptr )
      ::operator delete( p );
   }
 
   bool IsFastGrowthEnabled() const
   {
      return m_fastGrowth;
   }
 
   void EnableFastGrowth( bool enable = true )
   {
      m_fastGrowth = enable;
   }
 
   void DisableFastGrowth( bool disable = true )
   {
      EnableFastGrowth( !disable );
   }
 
   bool IsShrinkingEnabled() const
   {
      return m_canShrink;
   }
 
   void EnableShrinking( bool enable = true )
   {
      m_canShrink = enable;
   }
 
   void DisableShrinking( bool disable = true )
   {
      EnableShrinking( !disable );
   }
 
private:
 
   bool m_fastGrowth : 1;
   bool m_canShrink  : 1;
};
 
} // pcl
 
// ----------------------------------------------------------------------------
 
inline void* operator new( pcl::size_type, void* p, pcl::StandardAllocator& )
{
   PCL_PRECONDITION( p != nullptr )
   return p;
}
 
#ifdef _MSC_VER
#pragma warning( push )
#pragma warning( disable: 4100 ) // 'unreferenced formal parameter'
 
inline void operator delete( void* p, void*, pcl::StandardAllocator& )
{
   PCL_PRECONDITION( p != nullptr )
}
 
#pragma warning( pop )
#endif // _MSC_VER
 
// ----------------------------------------------------------------------------
 
#endif  // __PCL_StandardAllocator_h
 
// ----------------------------------------------------------------------------
// EOF pcl/StandardAllocator.h - Released 2024-06-18T15:48:54Z