/*

     File: CompressedPacketTable.cpp

 Abstract: CompressedPacketTable.h

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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)

    }

}

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