use VarInt

src/Common/Compression.cpp

@@ -1,5 +1,7 @@
 #include "Compression.h"
 
+#include "VarInt.h"
+
 #include <cassert>
 #include <zlib.h>
 
@@ -33,10 +35,7 @@ DataBuffer Compress(const DataBuffer& buffer) {
 
 	if (buffer.GetSize() < COMPRESSION_THRESHOLD) {
 		// Don't compress since it's a small packet
-		std::uint64_t compressedDataLength = 0;
-		std::uint64_t packetLength = compressedDataLength + buffer.GetSize();
-
-		packet << packetLength;
+		VarInt compressedDataLength = 0;
 		packet << compressedDataLength;
 		packet << buffer;
 		return packet;
@@ -44,22 +43,19 @@ DataBuffer Compress(const DataBuffer& buffer) {
 
 	DataBuffer compressedData = Deflate(buffer.data(), buffer.GetSize());
 
-	std::uint64_t uncompressedDataLength = buffer.GetSize();
-	std::uint64_t packetLength = uncompressedDataLength + compressedData.GetSize();
-
-	packet << packetLength;
+	VarInt uncompressedDataLength = buffer.GetSize();
 	packet << uncompressedDataLength;
 	packet.WriteSome(compressedData.data(), compressedData.GetSize());
 	return packet;
 }
 
 DataBuffer Decompress(DataBuffer& buffer, std::uint64_t packetLength) {
-	std::uint64_t uncompressedLength;
+	VarInt uncompressedLength;
 	buffer >> uncompressedLength;
 
-	std::uint64_t compressedLength = packetLength - uncompressedLength;
+	std::uint64_t compressedLength = packetLength - uncompressedLength.GetSerializedLength();
 
-	if (uncompressedLength == 0) {
+	if (uncompressedLength.GetValue() == 0) {
 		// Data already uncompressed. Nothing to do
 		DataBuffer ret;
 		buffer.ReadSome(ret, compressedLength);
@@ -68,12 +64,5 @@ DataBuffer Decompress(DataBuffer& buffer, std::uint64_t packetLength) {
 
 	assert(buffer.GetReadOffset() + compressedLength <= buffer.GetSize());
 
-	return Inflate(buffer.data() + buffer.GetReadOffset(), compressedLength, uncompressedLength);
-}
-
-DataBuffer Decompress(DataBuffer& buffer) {
-	std::uint64_t packetLength;
-	buffer >> packetLength;
-
-	return Decompress(buffer, packetLength);
+	return Inflate(buffer.data() + buffer.GetReadOffset(), compressedLength, uncompressedLength.GetValue());
 }

src/Common/Compression.h

@@ -14,13 +14,6 @@
  */
 DataBuffer Compress(const DataBuffer& buffer);
 
-/**
- * \brief Reads the packet lenght and uncompress it
- * \param buffer the data to uncompress
- * \return the uncompressed data
- */
-DataBuffer Decompress(DataBuffer& buffer);
-
 /**
  * \brief Uncompress some data
  * \param buffer the data to uncompress

src/Common/VarInt.cpp

@@ -0,0 +1,48 @@
+#include "VarInt.h"
+
+#include "DataBuffer.h"
+#include <stdexcept>
+
+static constexpr int SEGMENT_BITS = 0x7F;
+static constexpr int CONTINUE_BIT = 0x80;
+
+std::size_t VarInt::GetSerializedLength() const {
+	DataBuffer buffer;
+	buffer << *this;
+	return buffer.GetSize();
+}
+
+DataBuffer& operator<<(DataBuffer& out, const VarInt& var) {
+	std::uint64_t value = var.m_Value;
+	while (true) {
+		if ((value & ~static_cast<std::uint64_t>(SEGMENT_BITS)) == 0) {
+			out << static_cast<std::uint8_t>(value);
+			return out;
+		}
+
+		out << static_cast<std::uint8_t>((value & SEGMENT_BITS) | CONTINUE_BIT);
+
+		value >>= 7;
+	}
+}
+
+DataBuffer& operator>>(DataBuffer& in, VarInt& var) {
+	var.m_Value = 0;
+	unsigned int position = 0;
+	std::uint8_t currentByte;
+
+	while (true) {
+		in.ReadSome(&currentByte, 1);
+		var.m_Value |= static_cast<std::uint64_t>(currentByte & SEGMENT_BITS) << position;
+
+		if ((currentByte & CONTINUE_BIT) == 0)
+			break;
+
+		position += 7;
+
+		if (position >= 8 * sizeof(var.m_Value))
+			throw std::runtime_error("VarInt is too big");
+	}
+
+	return in;
+}

src/Common/VarInt.h

@@ -0,0 +1,54 @@
+#pragma once
+
+/**
+ * \file VarInt.h
+ * \brief File containing the blitz::VarInt class
+ */
+
+#include <cstddef>
+#include <cstdint>
+
+class DataBuffer;
+
+/**
+ * \class VarInt
+ * \brief Variable-length format such that smaller numbers use fewer bytes.
+ */
+class VarInt {
+  private:
+	std::uint64_t m_Value;
+
+  public:
+	VarInt() : m_Value(0) {}
+	/**
+	 * \brief Construct a variable integer from a value
+	 * \param value The value of the variable integer
+	 */
+	VarInt(std::uint64_t value) : m_Value(value) {}
+
+	/**
+	 * \brief Get the value of the variable integer
+	 */
+	std::uint64_t GetValue() const {
+		return m_Value;
+	}
+
+	/**
+	 * \brief Get the length of the serialized variable integer
+	 */
+	std::size_t GetSerializedLength() const;
+
+	/**
+	 * \brief Serialize the variable integer
+	 * \param out The buffer to write the serialized variable integer to
+	 * \param var The variable integer to serialize
+	 */
+	friend DataBuffer& operator<<(DataBuffer& out, const VarInt& var);
+
+	/**
+	 * \brief Deserialize the variable integer
+	 * \param in The buffer to read the serialized variable integer from
+	 * \param var The variable integer to deserialize
+	 */
+	friend DataBuffer& operator>>(DataBuffer& in, VarInt& var);
+};

src/Pieces/PiecesFiles.cpp

@@ -73,7 +73,7 @@ bool PiecesFiles::loadPieces(int polyominoSize, std::vector<Piece>& pieces, std:
     if(!compressed.ReadFile(filePath))
         return false;
 
-    DataBuffer buffer = Decompress(compressed);
+    DataBuffer buffer = Decompress(compressed, compressed.GetSize());
         
     std::ifstream piecesFile(filePath, std::ios::binary);
     if (!piecesFile.good()) {