livetrax/libs/appleutility/CoreAudio/AudioFile/AFPublic/CompressedPacketTable.h

/*
     File: CompressedPacketTable.h
 Abstract: Part of CoreAudio Utility Classes
  Version: 1.1
 
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*/
#include <iterator>
#include <vector>
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
	#include <CoreAudio/CoreAudioTypes.h>
#else
	#include "CoreAudioTypes.h"
#endif

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

struct  AudioStreamPacketDescriptionExtended : AudioStreamPacketDescription
{
    SInt64  mFrameOffset; // this is the sum of the mVariableFramesInPacket up to this point so we can binary search.
};
typedef struct AudioStreamPacketDescriptionExtended AudioStreamPacketDescriptionExtended;

inline bool operator < (const AudioStreamPacketDescriptionExtended& a, const AudioStreamPacketDescriptionExtended& b)
{
	return a.mFrameOffset < b.mFrameOffset;
}

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class CompressedPacketTable
{
public:
	CompressedPacketTable(UInt32 inFramesPerPacket) : mSize(0), mFramesPerPacket(inFramesPerPacket) {}
	~CompressedPacketTable();
	
	SInt64 size() const { return mSize; }
	void push_back(const AudioStreamPacketDescriptionExtended& inDesc);
	
	const AudioStreamPacketDescriptionExtended operator[](SInt64 inPacketIndex) const;
	const AudioStreamPacketDescriptionExtended front() const { return (*this)[0]; }
	const AudioStreamPacketDescriptionExtended back() const { return (*this)[mSize-1]; }
	
	//SInt64 PacketForByte(SInt64 inByteOffset) const;
	SInt64 ByteForPacket(SInt64 inPacketIndex) const { return (*this)[inPacketIndex].mStartOffset; }
		
	class iterator {
		public:
			typedef std::input_iterator_tag iterator_category;
			typedef iterator pointer;
			typedef SInt64 difference_type;
			typedef AudioStreamPacketDescriptionExtended value_type;
			typedef value_type& reference;
			
			iterator() : mTable(NULL), mIndex(0) {}
			iterator(const CompressedPacketTable* table, SInt64 index) : mTable(table), mIndex(index) {}
			iterator(const iterator& that) : mTable(that.mTable), mIndex(that.mIndex) {}
			
			iterator& operator=(const iterator& that) { mTable = that.mTable; mIndex = that.mIndex; return *this; }
			
			const AudioStreamPacketDescriptionExtended operator*() const { return (*mTable)[mIndex]; }
			const AudioStreamPacketDescriptionExtended* const operator->() { mValue = (*mTable)[mIndex]; return &mValue; }
			iterator& operator++() { ++mIndex; return *this; }
			iterator& operator--() { --mIndex; return *this; }
			
			SInt64 operator-(const iterator& that) { return mIndex - that.mIndex; }
			const iterator operator-(SInt64 index) { return iterator(mTable, mIndex - index); }
			const iterator operator+(SInt64 index) { return iterator(mTable, mIndex + index); }
			bool operator==(const iterator& that) { return mIndex == that.mIndex; }
			bool operator!=(const iterator& that) { return mIndex != that.mIndex; }
			bool operator>(const iterator& that) { return mIndex > that.mIndex; }
			bool operator<(const iterator& that) { return mIndex < that.mIndex; }
		private:
			const CompressedPacketTable* mTable;
			SInt64 mIndex;
			AudioStreamPacketDescriptionExtended mValue; // in order to support operator-> .
	};
	
	iterator begin() const { return iterator(this, 0); }
	iterator end() const { return iterator(this, mSize); }
	
private:
	struct TinyContiguousPacketDescription
	{
		UInt16 mNextOffset;
	};
	
	struct TinyDiscontiguousPacketDescription : TinyContiguousPacketDescription
	{
		UInt16 mDataByteSize;
	};
	
	// There could be a 24 bit packet description. But ALAC is who usually needs SmallContiguousPacketDescription and 
	// it already uses 8x fewer packet descriptions than AAC due to the mFramesPerPacket being 8x greater. 
	// So there isn't as great a need for saving space. 4 bytes per packet is OK for ALAC.
	
	struct SmallContiguousPacketDescription
	{
		UInt32 mNextOffset;
	};
	
	struct SmallDiscontiguousPacketDescription : SmallContiguousPacketDescription
	{
		UInt16 mDataByteSize;
	};
	
	struct BigContiguousPacketDescription
	{
		UInt64 mNextOffset;
	};
	
	struct BigDiscontiguousPacketDescription : BigContiguousPacketDescription
	{
		UInt32 mDataByteSize;
	};
	
	struct PacketBase
	{
		SInt64 mBaseOffset;
		UInt8 mDescType;
		void* mDescs;
	};
	
	enum {
		kTinyContiguousPacketDescription,
		kTinyDiscontiguousPacketDescription,
		kSmallContiguousPacketDescription,
		kSmallDiscontiguousPacketDescription,
		kBigContiguousPacketDescription,
		kBigDiscontiguousPacketDescription,
		kExtendedPacketDescription
	};
	static const UInt32 kShift;
	static const UInt32 kMask;
	
	bool isContiguous(PacketBase& base);
	bool hasVariableFrames(PacketBase& base);
	UInt32 largestPacket(PacketBase& base);
	
	void Compress(PacketBase& base);

private:	
	std::vector<PacketBase> mBases;
	UInt64 mSize;
	UInt32 mFramesPerPacket;
};