commit 512ec482f7eea0fec6568440cfdcc288725ac76f
Author: Martin Bauer <martin.bauer@fau.de>
Date:   Sat Aug 17 23:26:17 2019 +0200

    New firmware - with host mockup for testing

diff --git a/.idea/.gitignore b/.idea/.gitignore
new file mode 100644
index 0000000..5c98b42
--- /dev/null
+++ b/.idea/.gitignore
@@ -0,0 +1,2 @@
+# Default ignored files
+/workspace.xml
\ No newline at end of file
diff --git a/.idea/firmware.iml b/.idea/firmware.iml
new file mode 100644
index 0000000..f08604b
--- /dev/null
+++ b/.idea/firmware.iml
@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module classpath="CMake" type="CPP_MODULE" version="4" />
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
new file mode 100644
index 0000000..8822db8
--- /dev/null
+++ b/.idea/misc.xml
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CMakeWorkspace" PROJECT_DIR="$PROJECT_DIR$" />
+  <component name="JavaScriptSettings">
+    <option name="languageLevel" value="ES6" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/modules.xml b/.idea/modules.xml
new file mode 100644
index 0000000..cb860b6
--- /dev/null
+++ b/.idea/modules.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/firmware.iml" filepath="$PROJECT_DIR$/.idea/firmware.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 0000000..6c0b863
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/.." vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 0000000..dea4edf
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,4 @@
+cmake_minimum_required (VERSION 2.6)
+project (pooltrainer_firmware)
+
+add_executable(test sessiontest.cpp)
\ No newline at end of file
diff --git a/MockDtypes.h b/MockDtypes.h
new file mode 100644
index 0000000..3b57802
--- /dev/null
+++ b/MockDtypes.h
@@ -0,0 +1,40 @@
+#include <string>
+#include <cstdint>
+#include <cstring>
+#include <arpa/inet.h>
+#include <algorithm>
+#include <iostream>
+#include <sstream>
+
+typedef uint32_t uint_t;
+
+typedef std::string String;
+typedef uint8_t byte;
+typedef const char * PGM_P;
+
+using std::min;
+using std::max;
+
+inline uint32_t strlen_P(PGM_P str) {
+    return std::strlen(str);
+}
+
+inline const char * F( const char * in) { return in; }
+
+
+inline void _assert(const char* expression, const char* message, const char* file, int line)
+{
+    std::cerr << "Assert " << file << ":" << line << "  '" << expression << "' failed." << std::endl;
+    std::cerr << message << std::endl;
+
+    abort();
+}
+
+template< typename T>
+inline std::string toString(const T & t) {
+    std::stringstream stream;
+    stream << t;
+    return stream.str();
+}
+
+#define assert(EXPRESSION, MSG) ((EXPRESSION) ? (void)0 : _assert(#EXPRESSION, #MSG, __FILE__, __LINE__))
\ No newline at end of file
diff --git a/MockSerial.h b/MockSerial.h
new file mode 100644
index 0000000..6daaccb
--- /dev/null
+++ b/MockSerial.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <iostream>
+
+
+class SerialMock {
+public:
+    template< typename T>
+    static inline void print(const T & str) {
+        std::cout << str;
+    }
+    template< typename T>
+    static inline void println(const T & str) {
+        std::cout << str << std::endl;
+    }
+};
+
+static SerialMock Serial;
\ No newline at end of file
diff --git a/SessionChunkIO.h b/SessionChunkIO.h
new file mode 100644
index 0000000..af6b380
--- /dev/null
+++ b/SessionChunkIO.h
@@ -0,0 +1,28 @@
+#include <FS.h>
+#include <ESP8266WebServer.h>
+
+
+class ESP8266HttpMsgPackWriter {
+public:
+    HttpWriterAdaptor(ESP8266WebServer
+    * o)
+    :
+    obj_(o) {}
+
+    void write(const char *data, uint32_t size) {
+        obj_->sendContent_P(data, size);
+    }
+
+private:
+    ESP8266WebServer *obj_;
+};
+
+
+template<typename SessionChunk_T>
+void saveSessionChunkToFile(const SessionChunk_T &chunk, const String &fileName) {
+    String startTimeStr(chunk.getStartTime());
+    File f = SPIFFS.open(fileName, "w");
+    StreamingMsgPackEncoder<File> encoder(&f);
+    chunk.serialize(encoder);
+    f.close();
+}
diff --git a/config.h b/config.h
new file mode 100644
index 0000000..af74308
--- /dev/null
+++ b/config.h
@@ -0,0 +1,18 @@
+
+// WIFI Parameters
+const char* WIFI_SSID   = "RepeaterWZ";
+const char* WIFI_PASSWD = "Bau3rWLAN";
+const char* HOSTNAME = "swimtrainer";
+const bool CORS_HEADER = true;
+
+// HX711 connection
+const int LOADCELL_DOUT_PIN = D2;
+const int LOADCELL_SCK_PIN = D3;
+const int LED_PIN = D1;
+
+// Measurement parameters
+const int DELAY = 100;                // interval in ms between measurements
+const int SESSION_SIZE = 1024*8;      // how many data points are added to the session
+const byte MEASUREMENT_AVG_COUNT = 1; // averages over this many consecutive AD-converter reads
+const byte TARE_AVG_COUNT = 50;       // number of measurements in tare-phase (to find 0 )
+const int DIVIDER = 128;              // uint32 measurements are divided by this factor, before stored in uint16_t
diff --git a/firmware.ino b/firmware.ino
new file mode 100644
index 0000000..4357902
--- /dev/null
+++ b/firmware.ino
@@ -0,0 +1,138 @@
+#include "HX711.h"
+#include <ESP8266WiFi.h>
+#include <WiFiUdp.h> // for NTP
+#include <NTPClient.h> // for NTP
+#include <ESP8266WebServer.h>
+#include <FS.h>
+
+#include "config.h"
+
+
+int16_t compressMeasurement(int32_t value) {
+    return (int16_t)(measurement / DIVIDER)
+}
+
+
+
+HX711 scale;
+WiFiUDP ntpUDP;
+NTPClient timeClient(ntpUDP, "pool.ntp.org");
+TrainingSession session;
+ESP8266WebServer webServer(80);
+
+bool makeMeasurement(long & measurementOut)
+{
+    if (scale.is_ready())
+    {
+        measurementOut = scale.get_value(MEASUREMENT_AVG_COUNT);
+        return true;
+    }
+    else
+        return false;
+}
+
+
+void setup()
+{
+    digitalWrite(LED_PIN, HIGH);
+
+    // Serial
+    Serial.begin(115200);
+    while(!Serial) {}
+
+    // wifi
+    WiFi.mode(WIFI_STA);
+    WiFi.hostname(HOSTNAME);
+    WiFi.begin(WIFI_SSID, WIFI_PASSWD);
+
+    Serial.print(F("\n\n"));
+    Serial.println(F("Waiting for WIFI connection..."));
+    while (WiFi.status() != WL_CONNECTED) {
+        delay(1000);
+    }
+
+    Serial.print(F("Connected to WiFi. IP:"));
+    Serial.println(WiFi.localIP());
+
+    timeClient.begin();
+    timeClient.update();
+
+    // initialize cell
+    scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);
+    scale.tare( TARE_AVG_COUNT );
+
+    // NTP
+    session.init( &timeClient );
+    Serial.print("Initialized NTP client: ");
+    Serial.println(timeClient.getEpochTime());
+
+    // webserver
+    webServer.on("/api/session", [] () {
+        session.send(&webServer);
+    });
+    webServer.on("/api/save", [] () {
+        webServer.send(200, "text/plain", session.saveToFileSystem());
+    });
+    webServer.on("/api/tare", [] () {
+        scale.tare( TARE_AVG_COUNT );
+        webServer.send(200, "text/plain", "OK");
+    });
+    webServer.on("/", HTTP_GET, [](){
+        Serial.println("index.html requested");
+        File file = SPIFFS.open("/index.html", "r");
+        size_t sent = webServer.streamFile(file, "text/html");
+        file.close();
+    });
+    webServer.on("/swimtrainer.webmanifest", HTTP_GET, [](){
+        File file = SPIFFS.open("/swimtrainer.webmanifest", "r");
+        size_t sent = webServer.streamFile(file, "application/manifest+json");
+        file.close();
+    });
+
+
+
+    webServer.begin();
+    Serial.println("Webserver started");
+
+    // flash file system
+    if(!SPIFFS.begin()){
+        Serial.println("An Error has occurred while mounting SPIFFS");
+    }
+}
+
+
+void loop()
+{
+    const long cycleStart = millis();
+
+
+    digitalWrite(LED_PIN, HIGH);
+
+
+    long measurement = 0;
+    if(makeMeasurement(measurement))
+    {
+        session.addPoint(measurement);
+    } else {
+        Serial.println("Measurement skipped - cell not ready");
+    }
+
+    webServer.handleClient();
+
+    const long cycleDuration = millis() - cycleStart;
+    if( cycleDuration <= DELAY)
+    {
+        delay(DELAY - cycleDuration);
+    }
+    else
+    {
+        Serial.print("Skipping measurement, cycle duration was ");
+        Serial.println(cycleDuration);
+        const long skipped = (cycleDuration / DELAY);
+        //for(int i=0; i < skipped; ++i)
+        //  session.addPoint(0xFFFFFFFE);
+
+        delay(DELAY * (skipped + 1) - cycleDuration);
+    }
+
+}
\ No newline at end of file
diff --git a/session/MockStorage.h b/session/MockStorage.h
new file mode 100644
index 0000000..dc8d38d
--- /dev/null
+++ b/session/MockStorage.h
@@ -0,0 +1,68 @@
+#pragma once
+
+#include <stdio.h>
+#include <stdlib.h>
+
+
+class Adaptor {
+public:
+    Adaptor(const String &fileName) {
+        static const String baseDirectory(".");
+        auto fullFileName = baseDirectory + fileName;
+        fptr = fopen(fullFileName.c_str(), "wb");
+    }
+
+    ~Adaptor() {
+        fclose(fptr);
+    }
+
+    void write(const char *data, uint32_t size) {
+        fwrite(data, size, 1, fptr);
+    }
+
+private:
+    FILE * fptr;
+};
+
+
+class MockStorageWriter {
+public:
+    MockStorageWriter(const String &fileName) {
+        adaptor_ = new Adaptor(fileName);
+        encoder_ = new StreamingMsgPackEncoder <Adaptor>(adaptor_);
+    }
+    ~MockStorageWriter(){
+        delete adaptor_;
+        delete encoder_;
+    }
+    MockStorageWriter(const MockStorageWriter &) = delete;
+
+    StreamingMsgPackEncoder<Adaptor> &encoder() { return *encoder_; }
+
+private:
+    Adaptor * adaptor_;
+    StreamingMsgPackEncoder <Adaptor> * encoder_;
+
+};
+
+
+class MockStorageReader {
+public:
+    MockStorageReader(const String &fileName)
+    {
+        static const String baseDirectory(".");
+        auto fullFileName = baseDirectory + fileName;
+        fptr = fopen(fullFileName.c_str(), "rb");
+    }
+
+    uint32_t readBytes(char *buffer, size_t length) {
+        return fread(buffer, length, 1, fptr);
+    }
+
+    bool seek(uint32_t pos) {
+        auto ret = fseek(fptr, pos, SEEK_SET);
+        return ret == 0;
+    }
+private:
+    FILE * fptr;
+};
\ No newline at end of file
diff --git a/session/Session.h b/session/Session.h
new file mode 100644
index 0000000..8266f5b
--- /dev/null
+++ b/session/Session.h
@@ -0,0 +1,113 @@
+#include "SessionChunk.h"
+
+
+template<typename Measurement_T, typename Reader, typename Writer, uint_t CHUNK_SIZE>
+class Session {
+public:
+    typedef SessionChunk<Measurement_T, CHUNK_SIZE> Chunk_T;
+
+    Session()
+            : currentChunk(&chunks[0]),
+              otherChunk(&chunks[1]) {}
+
+    void init(uint32_t epochStartTime) {
+        currentChunk = &chunks[0];
+        currentChunk->init(epochStartTime, 0);
+    }
+
+    bool addPoint(Measurement_T measurement) {
+        const bool successful = currentChunk->addPoint(measurement);
+        if (!successful) {
+            rotate();
+            const bool secondInsertSuccess = currentChunk->addPoint(measurement);
+            assert(secondInsertSuccess, "Session: insertion after rotation failed");
+            //TODO check that there is place for file - remove old files
+        }
+        return true;
+    }
+
+    template<typename T>
+    void serialize(StreamingMsgPackEncoder<T> & encoder, uint32_t startIdx) const
+    {
+        const uint32_t lastIdx = currentChunk->getStartIndex() + currentChunk->numMeasurements();
+        if( lastIdx <= startIdx) {
+            encoder.sendArray(nullptr, 0);
+            return;
+        }
+
+        Chunk_T::sendHeader(encoder, currentChunk->getStartTime(), startIdx);
+        encoder.sendArrayHeader(lastIdx - startIdx);
+        while(startIdx < lastIdx)
+            startIdx = serializeChunk(encoder, startIdx);
+        assert(startIdx == lastIdx, "Not all data was sent");
+    }
+
+private:
+    void rotate() {
+        if( otherChunkFilled() )
+            saveChunkToFile(otherChunk);
+        swapChunks();
+
+        currentChunk->init(otherChunk->getStartTime(), otherChunk->getStartIndex() + CHUNK_SIZE);
+    }
+
+    bool otherChunkFilled() const {
+        return otherChunk->numMeasurements() > 0;
+    }
+
+    void swapChunks() {
+        Chunk_T *tmp = currentChunk;
+        currentChunk = otherChunk;
+        otherChunk = tmp;
+    }
+
+    void saveChunkToFile(Chunk_T *chunk) const {
+        const uint32_t chunkNr = chunk->getStartIndex() / CHUNK_SIZE;
+        const auto fileName = chunkFileName(chunkNr, chunk->getStartTime());
+        Writer writer( fileName );
+        chunk->serialize(writer.encoder());
+    };
+
+    template< typename T>
+    uint32_t serializeChunk(StreamingMsgPackEncoder<T> & encoder, uint32_t startIdx) {
+        assert( startIdx < currentChunk->getStartIndex() + currentChunk->numMeasurements(),
+                "serializeChunk: invalid startIdx" );
+
+        if( startIdx >= currentChunk->getStartIndex() ) {
+            encoder.sendArrayPartialContents( currentChunk->getDataPointer(), currentChunk->numMeasurements() );
+            return currentChunk->getStartIndex() +  currentChunk->numMeasurements();
+        } else if( startIdx >= otherChunk->getStartIndex() && otherChunkFilled() ) {
+            encoder.sendArrayPartialContents( otherChunk->getDataPointer(), otherChunk->numMeasurements() );
+            assert( otherChunk->numMeasurements(), CHUNK_SIZE );
+            return otherChunk->getStartIndex() + otherChunk->numMeasurements();
+        } else {
+            if( encoder.getSizeCountMode() ) {
+                encoder.sendArrayPartialContents(nullptr, CHUNK_SIZE);
+            } else {
+                const uint32_t chunkNr = startIdx / CHUNK_SIZE;
+                const auto chunkFileName = (chunkNr, currentChunk->getStartTime());
+                Reader reader(chunkFileName);
+                reader.seek(Chunk_T::valueOffset());
+
+                const uint32_t PART_SIZE = 32;
+                static_assert( PART_SIZE < CHUNK_SIZE  && CHUNK_SIZE % PART_SIZE == 0);
+
+                Measurement_T buffer[PART_SIZE];
+                for(uint32_t i = 0; i < CHUNK_SIZE; i += PART_SIZE)
+                {
+                    reader.readBytes((char*) buffer, sizeof(Measurement_T) * PART_SIZE);
+                    encoder.sendArrayPartialContents(buffer, PART_SIZE);
+                }
+            }
+            return startIdx + CHUNK_SIZE;
+        }
+    }
+
+    static String chunkFileName(uint32_t chunkNr, uint32_t startTime) {
+        return("/dat/" + toString(startTime) + "_" + toString(chunkNr));
+    }
+
+    Chunk_T chunks[2];
+    Chunk_T *currentChunk;
+    Chunk_T *otherChunk;
+};
diff --git a/session/SessionChunk.h b/session/SessionChunk.h
new file mode 100644
index 0000000..7718fe1
--- /dev/null
+++ b/session/SessionChunk.h
@@ -0,0 +1,108 @@
+#include "StreamingMsgPackEncoder.h"
+
+
+template<typename Measurement_T, uint_t SIZE>
+class SessionChunk
+{
+public:
+    SessionChunk()
+        : nextFree(0), sessionStartTime(0), startIndex(0)
+    {}
+
+    void init(uint32_t epochStartTime, uint32_t startIdx)
+    {
+        nextFree = 0;
+        sessionStartTime = epochStartTime;
+        startIndex = startIdx;
+    }
+
+    uint32_t getStartTime() const {
+        return sessionStartTime;
+    }
+
+    uint32_t getStartIndex() const {
+        return startIndex;
+    }
+
+    uint32_t numMeasurements() const {
+        return nextFree;
+    }
+
+    bool addPoint(Measurement_T measurement)
+    {
+        if( nextFree >= SIZE)
+            return false;
+        values[nextFree] = measurement;
+        nextFree++;
+
+        return true;
+    }
+
+    template<typename T>
+    void serialize(StreamingMsgPackEncoder<T> & encoder) const
+    {
+        sendHeader(encoder, sessionStartTime, startIndex);
+        encoder.sendArray(values + startIndex, nextFree - startIndex);
+    }
+
+    template<typename T>
+    void serialize(StreamingMsgPackEncoder<T> & encoder, uint32_t start, uint32_t end) const
+    {
+        if( start < this->startIndex )
+            start = this->startIndex;
+        if( end == 0 ) {
+            end = start + this->nextFree;
+        }
+
+        sendHeader(encoder, sessionStartTime, start);
+
+        bool sendEmpty =
+                (start >= end) ||
+                (end <= this->startIndex) ||
+                (start >= (this->startIndex + this->nextFree));
+        if( sendEmpty ) {
+            encoder.sendArray(nullptr, 0);
+        } else {
+            const uint32_t idxStart = (start - this->startIndex);
+            const uint32_t length = min(nextFree, end - start);
+            encoder.sendArray(values + idxStart, length);
+        }
+    }
+
+    template<typename T>
+    static uint32_t valueOffset()
+    {
+        StreamingMsgPackEncoder<T> encoder(nullptr);
+        encoder.setSizeCountMode(true);
+        sendHeader(encoder, 0, 0);
+        return encoder.getContentLength();
+    }
+
+    Measurement_T * getDataPointer() {
+        return values;
+    }
+
+    const Measurement_T * getDataPointer() const {
+        return values;
+    }
+
+    template<typename T>
+    static void sendHeader(StreamingMsgPackEncoder<T> & encoder, uint32_t sessionStartTime, uint32_t startIndex)
+    {
+        encoder.sendMap16(3);
+
+        encoder.sendString255("sessionStartTime");
+        encoder.sendInt(sessionStartTime);
+
+        encoder.sendString255("startIndex");
+        encoder.sendInt(startIndex);
+
+        encoder.sendString255("values");
+    }
+
+private:
+    uint32_t nextFree = 0;
+    uint32_t sessionStartTime;
+    uint32_t startIndex;
+    Measurement_T values[SIZE];
+};
\ No newline at end of file
diff --git a/session/SpiffsStorage.h b/session/SpiffsStorage.h
new file mode 100644
index 0000000..d4d625a
--- /dev/null
+++ b/session/SpiffsStorage.h
@@ -0,0 +1,36 @@
+#pragma once
+#include "StreamingMsgPackEncoder.h"
+#include <FS.h>
+
+
+class SpiffsStorageWriter {
+public:
+    SpiffsStorageWriter(const String &fileName) :
+            f_(SPIFFS.open(fileName, "w")),
+            encoder_(&f_) {}
+
+    StreamingMsgPackEncoder<File> &encoder() { return encoder_; }
+
+private:
+    File f_;
+    StreamingMsgPackEncoder<File> encoder_;
+};
+
+
+class SpiffsStorageReader
+{
+public:
+    SpiffsBackendReader(const String &fileName) :
+            f_(SPIFFS.open(fileName, "w"))
+    {}
+
+    uint32_t readBytes(char *buffer, size_t length) {
+        return f_.readBytes(buffer, length);
+    }
+
+    bool seek(uint32_t pos) {
+        return f_.seek(pos);
+    }
+private:
+    File f_;
+};
\ No newline at end of file
diff --git a/session/StreamingMsgPackEncoder.h b/session/StreamingMsgPackEncoder.h
new file mode 100644
index 0000000..5a357ea
--- /dev/null
+++ b/session/StreamingMsgPackEncoder.h
@@ -0,0 +1,126 @@
+
+template<typename T> struct TypeToMsgPackCode{};
+template<> struct TypeToMsgPackCode<uint8_t> { static const char CODE; };
+template<> struct TypeToMsgPackCode<uint16_t>{ static const char CODE; };
+template<> struct TypeToMsgPackCode<uint32_t>{ static const char CODE; };
+template<> struct TypeToMsgPackCode<int8_t>  { static const char CODE; };
+template<> struct TypeToMsgPackCode<int16_t> { static const char CODE; };
+template<> struct TypeToMsgPackCode<int32_t> { static const char CODE; };
+
+const char TypeToMsgPackCode<uint8_t>::CODE  = '\xcc';
+const char TypeToMsgPackCode<uint16_t>::CODE = '\xcd';
+const char TypeToMsgPackCode<uint32_t>::CODE = '\xce';
+const char TypeToMsgPackCode<int8_t>::CODE  = '\xd0';
+const char TypeToMsgPackCode<int16_t>::CODE = '\xd1';
+const char TypeToMsgPackCode<int32_t>::CODE = '\xd2';
+
+
+template<typename Writer>
+class StreamingMsgPackEncoder
+{
+public:
+    StreamingMsgPackEncoder(Writer * writer_)
+            : writer(writer_), contentLength(0), sizeCountMode(false)
+    {}
+
+    void sendMap16(byte size)
+    {
+        if( sizeCountMode )
+        {
+            contentLength += 1;
+        }
+        else
+        {
+            size |= 0b10000000;
+            writer->write((const char*)(&size), 1);
+        }
+    }
+
+    void sendString255(PGM_P s)
+    {
+        auto len = strlen_P(s);
+        if( len >= 255 ) {
+            Serial.println(F("ERROR: StreamingMsgPackEncoder::string255 - string too long"));
+            return;
+        }
+        byte castedLen = (byte)(len);
+
+        if( sizeCountMode )
+        {
+            contentLength += 2 + castedLen;
+        }
+        else
+        {
+            writer->write("\xd9", 1);
+            writer->write((const char*)&castedLen, 1);
+            writer->write(s, len);
+        }
+    }
+
+    template<typename T>
+    void sendInt(T value)
+    {
+        if( sizeCountMode )
+        {
+            contentLength += 1 + sizeof(T);
+        }
+        else
+        {
+            if( sizeof(T) == 4 )
+                value = htonl(value);
+            else if( sizeof(T) == 2)
+                value = htons(value);
+            writer->write(&TypeToMsgPackCode<T>::CODE, 1);
+            writer->write((const char*)&value, sizeof(T));
+        }
+    }
+
+    template<typename T>
+    void sendArray(const T * data, uint32_t length)
+    {
+        sendArrayHeader<T>(length);
+        sendArrayPartialContents(data, length);
+    }
+
+    template<typename T>
+    void sendArrayHeader(uint32_t length)
+    {
+        if( sizeCountMode )
+        {
+            contentLength += 1 + sizeof(uint32_t) + 1 + length * sizeof(T);
+        }
+        else
+        {
+            uint32_t nlength = htonl(length * sizeof(T));
+            writer->write("\xc9", 1); // ext dtype since typed arrays are not supported by msgpack
+            writer->write((char*)(&nlength), sizeof(uint32_t) );
+            writer->write(&TypeToMsgPackCode<T>::CODE, 1); // put code for type here, this is not part of msgpack but custom
+        }
+    }
+
+    template<typename T>
+    void sendArrayPartialContents(T * data, uint32_t length)
+    {
+        if( !sizeCountMode ) {
+            writer->write((char*)(data), length * sizeof(T));
+        }
+    }
+
+    void setSizeCountMode(bool sizeCountMode_=true)
+    {
+        sizeCountMode = sizeCountMode_;
+    }
+
+    bool getSizeCountMode() const {
+        return sizeCountMode;
+    }
+
+    uint32_t getContentLength() const {
+        return contentLength;
+    }
+
+private:
+    Writer * writer;
+    uint32_t contentLength;
+    bool sizeCountMode;
+};
diff --git a/sessiontest.cpp b/sessiontest.cpp
new file mode 100644
index 0000000..ca7a261
--- /dev/null
+++ b/sessiontest.cpp
@@ -0,0 +1,18 @@
+#include "MockDtypes.h"
+#include "MockSerial.h"
+#include "session/Session.h"
+#include "session/MockStorage.h"
+
+const uint32_t SESSION_SIZE = 128;
+typedef Session<uint16_t, MockStorageReader, MockStorageWriter, SESSION_SIZE> MockSession;
+
+int main(int argc, char**argv)
+{
+    MockSession session;
+
+    for( uint16_t i=0; i < SESSION_SIZE; ++i) {
+        session.addPoint(i);
+    }
+
+    return 0;
+}