JUCE/modules/juce_blocks_basics/littlefoot/juce_LittleFootRemoteHeap.h

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2016 - ROLI Ltd.

   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3

   Details of these licenses can be found at: www.gnu.org/licenses

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

   ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.juce.com for more information.

  ==============================================================================
*/

namespace littlefoot
{

using namespace juce;

//==============================================================================
/**
    This class manages the synchronisation of a remote block of heap memory used
    by a littlefoot program running on a block.

    Data in the block can be changed by calling setByte, setBytes, setBits etc, and
    these changes will be flushed to the device when sendChanges is called.
*/
template <typename ImplementationClass>
struct LittleFootRemoteHeap
{
    LittleFootRemoteHeap (uint32 blockSizeToUse) noexcept  : blockSize (blockSizeToUse)
    {
        resetDeviceStateToUnknown();
    }

    void clear() noexcept
    {
        zeromem (targetData, sizeof (targetData));
    }

    void setByte (size_t offset, uint8 value) noexcept
    {
        if (offset < blockSize)
        {
            if (targetData [offset] != value)
            {
                targetData [offset] = value;
                invalidateData();
            }
        }
        else
        {
            jassertfalse;
        }
    }

    void setBytes (size_t offset, const uint8* data, size_t num) noexcept
    {
        for (size_t i = 0; i < num; ++i)
            setByte (offset + i, data[i]);
    }

    void setBits (uint32 startBit, uint32 numBits, uint32 value) noexcept
    {
        if (startBit + numBits > 8 * blockSize)
        {
            jassertfalse;
            return;
        }

        if (readLittleEndianBitsInBuffer (targetData, startBit, numBits) != value)
        {
            writeLittleEndianBitsInBuffer (targetData, startBit, numBits, value);
            invalidateData();
        }
    }

    uint8 getByte (size_t offset) noexcept
    {
        if (offset < blockSize)
            return targetData [offset];

        jassertfalse;
        return 0;
    }

    void invalidateData()
    {
        dataHasChanged = true;
        programStateKnown = false;
    }

    void sendChanges (ImplementationClass& bi)
    {
        if (dataHasChanged && messagesSent.isEmpty())
        {
            for (;;)
            {
                uint16 data[ImplementationClass::maxBlockSize];
                uint32 packetIndex;

                if (messagesSent.isEmpty())
                {
                    for (uint32 i = 0; i < blockSize; ++i)
                        data[i] = deviceState[i];

                    packetIndex = lastPacketIndexReceived;
                }
                else
                {
                    auto& lastPacket = messagesSent.getReference (messagesSent.size() - 1);

                    for (uint32 i = 0; i < blockSize; ++i)
                        data[i] = lastPacket.resultDataState[i];

                    packetIndex = lastPacket.packetIndex;
                }

                packetIndex = (packetIndex + 1) & ImplementationClass::maxPacketCounter;

                if (! Diff (data, targetData, blockSize).createChangeMessage (bi, data, messagesSent, packetIndex))
                    break;

                dumpStatus();
            }
        }

        for (auto& m : messagesSent)
        {
            if (m.dispatchTime >= Time::getCurrentTime() - RelativeTime::milliseconds (250))
                break;

            m.dispatchTime = Time::getCurrentTime();
            bi.sendMessageToDevice (m.packet);
            //DBG ("Sending packet " << (int) m.packetIndex << " - " << m.packet.size() << " bytes, device " << bi.getDeviceIndex());

            if (getTotalSizeOfMessagesSent() > 200)
                break;
        }
    }

    void handleACKFromDevice (ImplementationClass& bi, uint32 packetIndex) noexcept
    {
        //DBG ("ACK " << (int) packetIndex);

        if (lastPacketIndexReceived != packetIndex)
        {
            lastPacketIndexReceived = packetIndex;

            for (int i = messagesSent.size(); --i >= 0;)
            {
                auto& m = messagesSent.getReference(i);

                if (m.packetIndex == packetIndex)
                {
                    for (uint32 j = 0; j < blockSize; ++j)
                        deviceState[j] = m.resultDataState[j];

                    messagesSent.removeRange (0, i + 1);
                    dumpStatus();
                    sendChanges (bi);

                    if (messagesSent.isEmpty())
                        dataHasChanged = false;

                    return;
                }
            }

            resetDeviceStateToUnknown();
        }
    }

    bool isProgramLoaded() noexcept
    {
        if (! programStateKnown)
        {
            uint8 deviceMemory[ImplementationClass::maxBlockSize];
            bool anyUnknowns = false;

            for (size_t i = 0; i < blockSize; ++i)
            {
                anyUnknowns = (deviceState[i] > 255);
                deviceMemory[i] = (uint8) deviceState[i];
            }

            programLoaded = ! anyUnknowns && littlefoot::Program (deviceMemory, (uint32) blockSize).checksumMatches();
            programStateKnown = true;
        }

        return programLoaded;
    }

    const size_t blockSize;

    static constexpr uint16 unknownByte = 0x100;

private:
    uint16 deviceState[ImplementationClass::maxBlockSize];
    uint8 targetData[ImplementationClass::maxBlockSize] = { 0 };
    bool dataHasChanged = true, programStateKnown = true, programLoaded = false;

    void resetDeviceStateToUnknown()
    {
        invalidateData();
        messagesSent.clear();

        for (uint32 i = 0; i < ImplementationClass::maxBlockSize; ++i)
            deviceState[i] = unknownByte;
    }

    struct ChangeMessage
    {
        typename ImplementationClass::PacketBuilder packet;
        Time dispatchTime;
        uint32 packetIndex;
        uint16 resultDataState[ImplementationClass::maxBlockSize];
    };

    Array<ChangeMessage> messagesSent;
    uint32 lastPacketIndexReceived = 0;

    int getTotalSizeOfMessagesSent() const noexcept
    {
        int total = 0;

        for (auto& m : messagesSent)
            if (m.dispatchTime != Time())
                total += m.packet.size();

        return total;
    }

    void dumpStatus()
    {
       #if DUMP_LITTLEFOOT_HEAP_STATUS
        int differences = 0;
        constexpr int diffLen = 50;
        char areas[diffLen + 1] = { 0 };

        for (int i = 0; i < diffLen; ++i)
            areas[i] = '.';

        for (int i = 0; i < (int) blockSize; ++i)
        {
            if (targetData[i] != deviceState[i])
            {
                ++differences;
                areas[i * diffLen / (int) blockSize] = 'X';
            }
        }

        double proportionOK = ((int) blockSize - differences) / (double) blockSize;

        juce::ignoreUnused (proportionOK);

        DBG ("Heap: " << areas << "  " << String (roundToInt (100 * proportionOK)) << "%  "
               << (isProgramLoaded() ? "Ready" : "Loading"));
       #endif
    }

    struct Diff
    {
        Diff (uint16* current, const uint8* target, size_t blockSizeToUse)
            : newData (target), blockSize (blockSizeToUse)
        {
            for (int i = 0; i < (int) blockSize; ++i)
                ranges.add ({ i, 1, newData[i] == current[i], false });

            coalesceUniformRegions();
            coalesceSequences();
            trim();
        }

        bool createChangeMessage (const ImplementationClass& bi,
                                  const uint16* currentState,
                                  Array<ChangeMessage>& messagesCreated,
                                  uint32 nextPacketIndex)
        {
            if (ranges.isEmpty())
                return false;

            auto deviceIndex = bi.getDeviceIndex();

            if (deviceIndex < 0)
                return false;

            messagesCreated.add ({});
            auto& message = messagesCreated.getReference (messagesCreated.size() - 1);

            message.packetIndex = nextPacketIndex;

            for (uint32 i = 0; i < blockSize; ++i)
                message.resultDataState[i] = currentState[i];

            auto& p = message.packet;
            p.writePacketSysexHeaderBytes ((uint8) deviceIndex);
            p.beginDataChanges (nextPacketIndex);

            uint8 lastValue = 0;
            bool packetOverflow = false;

            for (auto& r : ranges)
            {
                if (r.isSkipped)
                {
                    packetOverflow = ! p.skipBytes (r.length);
                }
                else if (r.isMixed)
                {
                    jassert (r.length > 1);
                    packetOverflow = ! p.setMultipleBytes (newData + r.index, r.length);

                    if (! packetOverflow)
                        lastValue = newData[r.index + r.length - 1];
                }
                else
                {
                    auto value = newData[r.index];
                    packetOverflow = ! p.setMultipleBytes (value, lastValue, r.length);

                    if (! packetOverflow)
                        lastValue = value;
                }

                if (packetOverflow)
                    break;

                if (! r.isSkipped)
                    for (int i = r.index; i < r.index + r.length; ++i)
                        message.resultDataState[i] = newData[i];
            }

            p.endDataChanges (! packetOverflow);
            p.writePacketSysexFooter();

            return packetOverflow;
        }

    private:
        struct ByteSequence
        {
            int index, length;
            bool isSkipped, isMixed;
        };

        const uint8* const newData;
        const size_t blockSize;
        Array<ByteSequence> ranges;

        void coalesceUniformRegions()
        {
            for (int i = 0; i < ranges.size() - 1; ++i)
            {
                auto& r1 = ranges.getReference (i);
                auto r2 = ranges.getReference (i + 1);

                if (r1.isSkipped == r2.isSkipped
                     && (r1.isSkipped || newData[r1.index] == newData[r2.index]))
                {
                    r1.length += r2.length;
                    ranges.remove (i + 1);
                    i = jmax (0, i - 2);
                }
            }
        }

        void coalesceSequences()
        {
            for (int i = 0; i < ranges.size() - 1; ++i)
            {
                auto& r1 = ranges.getReference (i);
                auto r2 = ranges.getReference (i + 1);

                if (! (r1.isSkipped || r2.isSkipped)
                     && (r1.isMixed || r1.length == 1)
                     && (r2.isMixed || r2.length == 1))
                {
                    if (r1.length + r2.length < 32)
                    {
                        r1.length += r2.length;
                        r1.isMixed = true;
                        ranges.remove (i + 1);
                        i = jmax (0, i - 2);
                    }
                }
            }
        }

        void trim()
        {
            while (ranges.size() > 0 && ranges.getLast().isSkipped)
                ranges.removeLast();
        }
    };
};

}