Further compression and png work.

src/core/streams/BufferBitStream.cpp

@@ -0,0 +1,49 @@
+#include "BufferBitStream.h"
+
+bool BufferBitStream::isFinished() const
+{
+    return mByteOffset == mBuffer.size();
+}
+
+std::vector<unsigned char> BufferBitStream::peekNextNBytes(unsigned n) const
+{
+    std::vector<unsigned char> ret (n, 0);
+    unsigned count = 0;
+    for(unsigned idx=mByteOffset; idx<mByteOffset + n; idx++)
+    {
+        if (idx == mBuffer.size())
+        {
+            break;
+        }
+
+        ret[count] = mBuffer[idx];
+        count ++;
+    }
+    return ret;
+}
+
+std::optional<unsigned char> BufferBitStream::readNextByte()
+{
+    if (mByteOffset + 1 == mBuffer.size())
+    {
+        return std::nullopt;
+    }
+    else
+    {
+        mByteOffset++;
+        mCurrentByte = mBuffer[mByteOffset];
+        return mCurrentByte;
+    }
+}
+
+void BufferBitStream::setBuffer(const std::vector<unsigned char>& data)
+{
+    mBuffer = data;
+}
+
+void BufferBitStream::writeByte(unsigned char data)
+{
+    mBuffer.push_back(data);
+}
+
+