/*
     File: CompressedPacketTable.cpp
 Abstract: CompressedPacketTable.h
  Version: 1.1

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*/
#include "CompressedPacketTable.h"
#include "CAAutoDisposer.h"

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

const UInt32 CompressedPacketTable::kShift = 5;
const UInt32 CompressedPacketTable::kMask = 31;

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

CompressedPacketTable::~CompressedPacketTable()
{
	size_t size = mBases.size();
	for (size_t i = 0; i < size; ++i) {
		free(mBases[i].mDescs);
	}
}

void CompressedPacketTable::push_back(const AudioStreamPacketDescriptionExtended& inDesc)
{
	SInt64 baseIndex = mSize >> kShift;
	UInt32 packetIndex = (UInt32)(mSize & kMask);

	if (packetIndex == 0) {
		// first packet in a new sequence. create a new PacketBase.
		PacketBase newBase;
		newBase.mBaseOffset = 0;
		newBase.mDescs = CA_malloc((kMask+1) * sizeof(AudioStreamPacketDescriptionExtended));
		newBase.mDescType = kExtendedPacketDescription;
		mBases.push_back(newBase);
	}

	PacketBase& base = mBases[(size_t)baseIndex];
	AudioStreamPacketDescriptionExtended* descs = (AudioStreamPacketDescriptionExtended*)base.mDescs;
	descs[packetIndex] = inDesc;

	if (packetIndex == kMask) {
		// last packet in a sequence. compress the sequence.
		Compress(base);
	}

	mSize++;
}

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

#define ACCESS_TYPE(TYPE) \
		case k##TYPE##ContiguousPacketDescription : { \
			TYPE##ContiguousPacketDescription* descs = (TYPE##ContiguousPacketDescription*)base.mDescs; \
			packetOffset = packetIndex ? descs[packetIndex-1].mNextOffset : 0; \
			packetSize = (UInt32)(descs[packetIndex].mNextOffset - packetOffset); \
		} break; \
		case k##TYPE##DiscontiguousPacketDescription : { \
			TYPE##DiscontiguousPacketDescription* descs = (TYPE##DiscontiguousPacketDescription*)base.mDescs; \
			packetOffset = packetIndex ? descs[packetIndex-1].mNextOffset : 0; \
			packetSize = descs[packetIndex].mDataByteSize; \
		} break;

const AudioStreamPacketDescriptionExtended CompressedPacketTable::operator[](SInt64 inPacketIndex) const
{
	SInt64 baseIndex = inPacketIndex >> kShift;
	UInt32 packetIndex = (UInt32)(inPacketIndex & kMask);

	if ((size_t)baseIndex >= mBases.size())
		throw -1;

	const PacketBase& base = mBases[(size_t)baseIndex];

	SInt64 packetOffset = 0;
	UInt32 packetSize = 0;

	switch (base.mDescType)
	{
		ACCESS_TYPE(Tiny)
		ACCESS_TYPE(Small)
		ACCESS_TYPE(Big)
		case kExtendedPacketDescription :
			return ((AudioStreamPacketDescriptionExtended*)base.mDescs)[packetIndex];
	}

	AudioStreamPacketDescriptionExtended outDesc;
	outDesc.mStartOffset = base.mBaseOffset + packetOffset;
	outDesc.mDataByteSize = packetSize;
	outDesc.mVariableFramesInPacket = 0;
	outDesc.mFrameOffset = mFramesPerPacket * inPacketIndex;

	//printf("get %d %10qd   %10qd %2d   %10qd %6d %10qd\n", base.mDescType, inPacketIndex, baseIndex, packetIndex, outDesc.mStartOffset, outDesc.mDataByteSize, outDesc.mFrameOffset);

	return outDesc;
}

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

bool CompressedPacketTable::isContiguous(PacketBase& base)
{
	AudioStreamPacketDescriptionExtended* descs = (AudioStreamPacketDescriptionExtended*)base.mDescs;
	SInt64 expectedOffset = descs[0].mStartOffset + descs[0].mDataByteSize;
	for (UInt32 i = 1; i <= kMask; ++i) {
		if (expectedOffset != descs[i].mStartOffset) return false;
		expectedOffset += descs[i].mDataByteSize;
	}
	return true;
}

bool CompressedPacketTable::hasVariableFrames(PacketBase& base)
{
	AudioStreamPacketDescriptionExtended* descs = (AudioStreamPacketDescriptionExtended*)base.mDescs;
	for (UInt32 i = 0; i <= kMask; ++i) {
		if (descs[i].mVariableFramesInPacket) return true;
	}
	return false;
}

UInt32 CompressedPacketTable::largestPacket(PacketBase& base)
{
	UInt32 maxPacketSize = 0;
	AudioStreamPacketDescriptionExtended* descs = (AudioStreamPacketDescriptionExtended*)base.mDescs;
	for (UInt32 i = 0; i <= kMask; ++i) {
		UInt32 packetSize = descs[i].mDataByteSize;
		if (packetSize > maxPacketSize) maxPacketSize = packetSize;
	}
	return maxPacketSize;
}

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

#define COMPRESS_TYPE(TYPE, BITS) \
	if (contiguous) { \
		TYPE##ContiguousPacketDescription* newDescs = (TYPE##ContiguousPacketDescription*)CA_malloc((kMask+1) * sizeof(TYPE##ContiguousPacketDescription)); \
		base.mDescs = newDescs; \
		base.mDescType = k##TYPE##ContiguousPacketDescription; \
		for (UInt32 i = 0; i <= kMask; ++i) { \
			newDescs[i].mNextOffset = (BITS)(descs[i].mStartOffset + descs[i].mDataByteSize - baseOffset); \
		} \
		free(descs); \
	} else { \
		TYPE##DiscontiguousPacketDescription* newDescs = (TYPE##DiscontiguousPacketDescription*)CA_malloc((kMask+1) * sizeof(TYPE##DiscontiguousPacketDescription)); \
		base.mDescs = newDescs; \
		base.mDescType = k##TYPE##DiscontiguousPacketDescription; \
		for (UInt32 i = 0; i <= kMask; ++i) { \
			newDescs[i].mNextOffset = i == kMask ? 0 : (BITS)(descs[i+1].mStartOffset - baseOffset); \
			newDescs[i].mDataByteSize = descs[i].mDataByteSize; \
		} \
		free(descs); \
	} \
	return;

void CompressedPacketTable::Compress(PacketBase& base)
{
	if (hasVariableFrames(base))
		return;

	bool contiguous = isContiguous(base);

	AudioStreamPacketDescriptionExtended* descs = (AudioStreamPacketDescriptionExtended*)base.mDescs;
	SInt64 delta = descs[kMask].mStartOffset + descs[kMask].mDataByteSize - descs[0].mStartOffset;

	SInt64 baseOffset = descs[0].mStartOffset;
	base.mBaseOffset = baseOffset;

	if (delta <= 65535LL) {
		COMPRESS_TYPE(Tiny, UInt16)
	} else if (delta <= 4294967295LL && largestPacket(base) <= 65535) {
		COMPRESS_TYPE(Small, UInt32)
	} else {
		COMPRESS_TYPE(Big, SInt64)
	}
}

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