Continue png writing.

src/core/streams/AbstractChecksumCalculator.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "stdint.h"
+
+class AbstractChecksumCalculator
+{
+public:
+    virtual ~AbstractChecksumCalculator() = default;
+
+    virtual void addValue(unsigned char val) = 0;
+    virtual uint32_t getChecksum() const = 0;
+
+    virtual void reset()
+    {
+    }
+};

src/core/streams/BitStream.cpp

@@ -28,6 +28,15 @@ void BitStream::write(uint32_t data)
     }
 }
 
+void BitStream::writeWord(uint16_t data)
+{
+    unsigned num_bytes = sizeof(uint16_t);
+    for(unsigned idx=0; idx<num_bytes;idx++)
+    {
+        writeByte(ByteUtils::getByteN(data, idx));
+    }
+}
+
 int BitStream::getCurrentByteOffset() const
 {
     return mByteOffset;

src/core/streams/BitStream.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include "AbstractChecksumCalculator.h"
+
 #include <vector>
 #include <string>
 #include <optional>
@@ -29,11 +31,39 @@ public:
 
     void write(uint32_t data);
 
+    void writeWord(uint16_t data);
+
     virtual void writeBytes(const std::vector<unsigned char> data) = 0;
 
+    void resetOffsets()
+    {
+        mByteOffset = -1;
+        mBitOffset = 0;
+    }
+
+    virtual void reset()
+    {
+        resetOffsets();
+        mCurrentByte = 0;
+    }
+
+    void setChecksumCalculator(AbstractChecksumCalculator* calc)
+    {
+        mChecksumCalculator = calc;
+    }
+
+    void clearChecksumCalculator()
+    {
+        mChecksumCalculator = nullptr;
+    }
+
+    //unsigned getSize() = 0;
+
 protected:
-    int mByteOffset{0};
+    int mByteOffset{-1};
     unsigned mBitOffset{0};
 
     unsigned char mCurrentByte{0};
+
+    AbstractChecksumCalculator* mChecksumCalculator{nullptr};
 };

src/core/streams/BufferBitStream.cpp

@@ -1,8 +1,10 @@
 #include "BufferBitStream.h"
 
+#include <iostream>
+
 bool BufferBitStream::isFinished() const
 {
-    return mByteOffset == mBuffer.size();
+    return mByteOffset == mBuffer.size() - 1;
 }
 
 std::vector<unsigned char> BufferBitStream::peekNextNBytes(unsigned n) const
@@ -43,6 +45,10 @@ void BufferBitStream::setBuffer(const std::vector<unsigned char>& data)
 
 void BufferBitStream::writeByte(unsigned char data)
 {
+    if (mChecksumCalculator)
+    {
+        mChecksumCalculator->addValue(data);
+    }
     mBuffer.push_back(data);
 }
 

src/core/streams/BufferBitStream.h

@@ -27,12 +27,13 @@ public:
         return mBuffer;
     }
 
-    void resetOffsets()
+    void reset() override
     {
-        mByteOffset = 0;
-        mBitOffset = 0;
+        BitStream::reset();
+        mBuffer.clear();
     }
 
 private:
+    unsigned mBufferSize{0};
     std::vector<unsigned char> mBuffer;
 };