//******************************************************************************************************//  TSSCDecoder.cpp - Gbtc////  Copyright © 2018, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the MIT License (MIT), the "License"; you may not use this//  file except in compliance with the License. You may obtain a copy of the License at:////      http://opensource.org/licenses/MIT////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  04/11/2018 - J. Ritchie Carroll//       Generated original version of source code.////****************************************************************************************************** #include "TSSCDecoder.h"#include "Constants.h" using namespace std;using namespace GSF;using namespace GSF::TimeSeries;using namespace GSF::TimeSeries::Transport; uint32_t Decode7BitUInt32(const uint8_t* stream, uint32_t& position);uint64_t Decode7BitUInt64(const uint8_t* stream, uint32_t& position); TSSCDecoder::TSSCDecoder() :    m_data(nullptr),    m_position(0),    m_lastPosition(0),    m_prevTimestamp1(0L),    m_prevTimestamp2(0L),    m_prevTimeDelta1(Int64::MaxValue),    m_prevTimeDelta2(Int64::MaxValue),    m_prevTimeDelta3(Int64::MaxValue),    m_prevTimeDelta4(Int64::MaxValue),        m_bitStreamCount(0),    m_bitStreamCache(0){    m_lastPoint = NewTSSCPointMetadata();} void TSSCDecoder::Reset(){    m_data = nullptr;    m_points.clear();    m_lastPoint = NewTSSCPointMetadata();    m_position = 0;    m_lastPosition = 0;    ClearBitStream();    m_prevTimeDelta1 = Int64::MaxValue;    m_prevTimeDelta2 = Int64::MaxValue;    m_prevTimeDelta3 = Int64::MaxValue;    m_prevTimeDelta4 = Int64::MaxValue;    m_prevTimestamp1 = 0L;    m_prevTimestamp2 = 0L;} TSSCPointMetadataPtr TSSCDecoder::NewTSSCPointMetadata(){    return NewSharedPtr<TSSCPointMetadata>([this]() { return ReadBit(); }, [this]() { return ReadBits5(); });} void TSSCDecoder::SetBuffer(uint8_t* data, uint32_t offset, uint32_t length){    ClearBitStream();    m_data = data;    m_position = offset;    m_lastPosition = length;} bool TSSCDecoder::TryGetMeasurement(uint16_t& id, int64_t& timestamp, uint32_t& quality, float32_t& value){    if (m_position == m_lastPosition && BitStreamIsEmpty())    {        ClearBitStream();        id = 0;        timestamp = 0;        quality = 0;        value = 0.0F;        return false;    }     //Note: since I will not know the incoming pointID. The most recent    //      measurement received will be the one that contains the     //      coding algorithm for this measurement. Since for the more part    //      measurements generally have some sort of sequence to them,     //      this still ends up being a good enough assumption.     int32_t code = m_lastPoint->ReadCode();     if (code == TSSCCodeWords::EndOfStream)    {        ClearBitStream();        id = 0;        timestamp = 0;        quality = 0;        value = 0.0F;        return false;    }     if (code <= TSSCCodeWords::PointIDXOR16)    {        DecodePointID(code, m_lastPoint);        code = m_lastPoint->ReadCode();                if (code < TSSCCodeWords::TimeDelta1Forward)        {            stringstream errorMessageStream;             errorMessageStream << "Expecting code >= ";            errorMessageStream << static_cast<int>(TSSCCodeWords::TimeDelta1Forward);            errorMessageStream << " Received ";            errorMessageStream << static_cast<int>(code);            errorMessageStream << " at position ";            errorMessageStream << static_cast<int>(m_position);            errorMessageStream << " with last position ";            errorMessageStream << static_cast<int>(m_lastPosition);             throw SubscriberException(errorMessageStream.str());        }    }     id = m_lastPoint->PrevNextPointId1;        TSSCPointMetadataPtr nextPoint = id >= m_points.size() ? nullptr : m_points[id];        if (nextPoint == nullptr)    {        nextPoint = NewTSSCPointMetadata();         if (id >= m_points.size())            m_points.resize(id + 1, nullptr);         m_points[id] = nextPoint;                nextPoint->PrevNextPointId1 = static_cast<uint16_t>(id + 1);    }     if (code <= TSSCCodeWords::TimeXOR7Bit)    {        timestamp = DecodeTimestamp(code);        code = m_lastPoint->ReadCode();         if (code < TSSCCodeWords::Quality2)        {            stringstream errorMessageStream;             errorMessageStream << "Expecting code >= ";            errorMessageStream << static_cast<int>(TSSCCodeWords::Quality2);            errorMessageStream << " Received ";            errorMessageStream << static_cast<int>(code);            errorMessageStream << " at position ";            errorMessageStream << static_cast<int>(m_position);            errorMessageStream << " with last position ";            errorMessageStream << static_cast<int>(m_lastPosition);             throw SubscriberException(errorMessageStream.str());        }    }    else    {        timestamp = m_prevTimestamp1;    }     if (code <= TSSCCodeWords::Quality7Bit32)    {        quality = DecodeQuality(code, nextPoint);        code = m_lastPoint->ReadCode();                if (code < TSSCCodeWords::Value1)        {            stringstream errorMessageStream;             errorMessageStream << "Expecting code >= ";            errorMessageStream << static_cast<int>(TSSCCodeWords::Value1);            errorMessageStream << " Received ";            errorMessageStream << static_cast<int>(code);            errorMessageStream << " at position ";            errorMessageStream << static_cast<int>(m_position);            errorMessageStream << " with last position ";            errorMessageStream << static_cast<int>(m_lastPosition);             throw SubscriberException(errorMessageStream.str());        }    }    else    {        quality = nextPoint->PrevQuality1;    }     //Since value will almost always change,     //This is not put inside a function call.    uint32_t valueRaw;     if (code == TSSCCodeWords::Value1)    {        valueRaw = nextPoint->PrevValue1;    }    else if (code == TSSCCodeWords::Value2)    {        valueRaw = nextPoint->PrevValue2;        nextPoint->PrevValue2 = nextPoint->PrevValue1;        nextPoint->PrevValue1 = valueRaw;    }    else if (code == TSSCCodeWords::Value3)    {        valueRaw = nextPoint->PrevValue3;        nextPoint->PrevValue3 = nextPoint->PrevValue2;        nextPoint->PrevValue2 = nextPoint->PrevValue1;        nextPoint->PrevValue1 = valueRaw;    }    else if (code == TSSCCodeWords::ValueZero)    {        valueRaw = 0;        nextPoint->PrevValue3 = nextPoint->PrevValue2;        nextPoint->PrevValue2 = nextPoint->PrevValue1;        nextPoint->PrevValue1 = valueRaw;    }    else    {        switch (code)        {            case TSSCCodeWords::ValueXOR4:                valueRaw = static_cast<uint32_t>(ReadBits4()) ^ nextPoint->PrevValue1;                break;            case TSSCCodeWords::ValueXOR8:                valueRaw = static_cast<uint32_t>(m_data[m_position]) ^ nextPoint->PrevValue1;                m_position++;                break;            case TSSCCodeWords::ValueXOR12:                valueRaw = static_cast<uint32_t>(ReadBits4()) ^ static_cast<uint32_t>(m_data[m_position] << 4) ^ nextPoint->PrevValue1;                m_position++;                break;            case TSSCCodeWords::ValueXOR16:                valueRaw = static_cast<uint32_t>(m_data[m_position]) ^ static_cast<uint32_t>(m_data[m_position + 1] << 8) ^ nextPoint->PrevValue1;                m_position += 2;                break;            case TSSCCodeWords::ValueXOR20:                valueRaw = static_cast<uint32_t>(ReadBits4()) ^ static_cast<uint32_t>(m_data[m_position] << 4) ^ static_cast<uint32_t>(m_data[m_position + 1] << 12) ^ nextPoint->PrevValue1;                m_position += 2;                break;            case TSSCCodeWords::ValueXOR24:                valueRaw = static_cast<uint32_t>(m_data[m_position]) ^ static_cast<uint32_t>(m_data[m_position + 1] << 8) ^ static_cast<uint32_t>(m_data[m_position + 2] << 16) ^ nextPoint->PrevValue1;                m_position += 3;                break;            case TSSCCodeWords::ValueXOR28:                valueRaw = static_cast<uint32_t>(ReadBits4()) ^ static_cast<uint32_t>(m_data[m_position] << 4) ^ static_cast<uint32_t>(m_data[m_position + 1] << 12) ^ static_cast<uint32_t>(m_data[m_position + 2] << 20) ^ nextPoint->PrevValue1;                m_position += 3;                break;            case TSSCCodeWords::ValueXOR32:                valueRaw = static_cast<uint32_t>(m_data[m_position]) ^ static_cast<uint32_t>(m_data[m_position + 1] << 8) ^ static_cast<uint32_t>(m_data[m_position + 2] << 16) ^ static_cast<uint32_t>(m_data[m_position + 3] << 24) ^ nextPoint->PrevValue1;                m_position += 4;                break;            default:                stringstream errorMessageStream;                 errorMessageStream << "Invalid code received ";                errorMessageStream << static_cast<int>(code);                errorMessageStream << " at position ";                errorMessageStream << static_cast<int>(m_position);                errorMessageStream << " with last position ";                errorMessageStream << static_cast<int>(m_lastPosition);                 throw SubscriberException(errorMessageStream.str());        }         nextPoint->PrevValue3 = nextPoint->PrevValue2;        nextPoint->PrevValue2 = nextPoint->PrevValue1;        nextPoint->PrevValue1 = valueRaw;    }     value = *reinterpret_cast<float32_t*>(&valueRaw);    m_lastPoint = nextPoint;     return true;} void TSSCDecoder::DecodePointID(uint8_t code, const TSSCPointMetadataPtr& lastPoint){    if (code == TSSCCodeWords::PointIDXOR4)    {        lastPoint->PrevNextPointId1 ^= static_cast<uint16_t>(ReadBits4());    }    else if (code == TSSCCodeWords::PointIDXOR8)    {        lastPoint->PrevNextPointId1 ^= static_cast<uint16_t>(m_data[m_position++]);    }    else if (code == TSSCCodeWords::PointIDXOR12)    {        lastPoint->PrevNextPointId1 ^= static_cast<uint16_t>(ReadBits4());        lastPoint->PrevNextPointId1 ^= static_cast<uint16_t>(m_data[m_position++] << 4);    }    else    {        lastPoint->PrevNextPointId1 ^= static_cast<uint16_t>(m_data[m_position++]);        lastPoint->PrevNextPointId1 ^= static_cast<uint16_t>(m_data[m_position++] << 8);    }} int64_t TSSCDecoder::DecodeTimestamp(uint8_t code){    int64_t timestamp;     if (code == TSSCCodeWords::TimeDelta1Forward)    {        timestamp = m_prevTimestamp1 + m_prevTimeDelta1;    }    else if (code == TSSCCodeWords::TimeDelta2Forward)    {        timestamp = m_prevTimestamp1 + m_prevTimeDelta2;    }    else if (code == TSSCCodeWords::TimeDelta3Forward)    {        timestamp = m_prevTimestamp1 + m_prevTimeDelta3;    }    else if (code == TSSCCodeWords::TimeDelta4Forward)    {        timestamp = m_prevTimestamp1 + m_prevTimeDelta4;    }    else if (code == TSSCCodeWords::TimeDelta1Reverse)    {        timestamp = m_prevTimestamp1 - m_prevTimeDelta1;    }    else if (code == TSSCCodeWords::TimeDelta2Reverse)    {        timestamp = m_prevTimestamp1 - m_prevTimeDelta2;    }    else if (code == TSSCCodeWords::TimeDelta3Reverse)    {        timestamp = m_prevTimestamp1 - m_prevTimeDelta3;    }    else if (code == TSSCCodeWords::TimeDelta4Reverse)    {        timestamp = m_prevTimestamp1 - m_prevTimeDelta4;    }    else if (code == TSSCCodeWords::Timestamp2)    {        timestamp = m_prevTimestamp2;    }    else    {        timestamp = m_prevTimestamp1 ^ static_cast<int64_t>(Decode7BitUInt64(&m_data[0], m_position));    }     // Save the smallest delta time    const int64_t minDelta = abs(m_prevTimestamp1 - timestamp);     if (minDelta < m_prevTimeDelta4 && minDelta != m_prevTimeDelta1 && minDelta != m_prevTimeDelta2 && minDelta != m_prevTimeDelta3)    {        if (minDelta < m_prevTimeDelta1)        {            m_prevTimeDelta4 = m_prevTimeDelta3;            m_prevTimeDelta3 = m_prevTimeDelta2;            m_prevTimeDelta2 = m_prevTimeDelta1;            m_prevTimeDelta1 = minDelta;        }        else if (minDelta < m_prevTimeDelta2)        {            m_prevTimeDelta4 = m_prevTimeDelta3;            m_prevTimeDelta3 = m_prevTimeDelta2;            m_prevTimeDelta2 = minDelta;        }        else if (minDelta < m_prevTimeDelta3)        {            m_prevTimeDelta4 = m_prevTimeDelta3;            m_prevTimeDelta3 = minDelta;        }        else        {            m_prevTimeDelta4 = minDelta;        }    }     m_prevTimestamp2 = m_prevTimestamp1;    m_prevTimestamp1 = timestamp;     return timestamp;} uint32_t TSSCDecoder::DecodeQuality(uint8_t code, const TSSCPointMetadataPtr& nextPoint){    uint32_t quality;     if (code == TSSCCodeWords::Quality2)    {        quality = nextPoint->PrevQuality2;    }    else    {        quality = Decode7BitUInt32(&m_data[0], m_position);    }     nextPoint->PrevQuality2 = nextPoint->PrevQuality1;    nextPoint->PrevQuality1 = quality;     return quality;} bool TSSCDecoder::BitStreamIsEmpty() const{    return m_bitStreamCount == 0;} void TSSCDecoder::ClearBitStream(){    m_bitStreamCount = 0;    m_bitStreamCache = 0;} int32_t TSSCDecoder::ReadBit(){    if (m_bitStreamCount == 0)    {        m_bitStreamCount = 8;        m_bitStreamCache = static_cast<int32_t>(m_data[m_position++]);    }     m_bitStreamCount--;        return (m_bitStreamCache >> m_bitStreamCount) & 1;} int32_t TSSCDecoder::ReadBits4(){    return ReadBit() << 3 | ReadBit() << 2 | ReadBit() << 1 | ReadBit();;} int32_t TSSCDecoder::ReadBits5(){    return ReadBit() << 4 | ReadBit() << 3 | ReadBit() << 2 | ReadBit() << 1 | ReadBit();;} uint32_t Decode7BitUInt32(const uint8_t* stream, uint32_t& position){    stream += position;        uint32_t value = *stream;        if (value < 128)    {        position++;        return value;    }        value ^= (static_cast<uint32_t>(stream[1]) << 7);        if (value < 16384)    {        position += 2;        return value ^ 0x80;    }        value ^= (static_cast<uint32_t>(stream[2]) << 14);        if (value < 2097152)    {        position += 3;        return value ^ 0x4080;    }        value ^= (static_cast<uint32_t>(stream[3]) << 21);        if (value < 268435456)    {        position += 4;        return value ^ 0x204080;    }        value ^= (static_cast<uint32_t>(stream[4])  << 28);    position += 5;        return value ^ 0x10204080;} uint64_t Decode7BitUInt64(const uint8_t* stream, uint32_t& position){    stream += position;    uint64_t value = *stream;     if (value < 128UL)    {        position++;        return value;    }        value ^= (static_cast<uint64_t>(stream[1]) << 7);        if (value < 16384UL)    {        position += 2;        return value ^ 0x80UL;    }    

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