Refactoring (2)

BlockDecoder.cpp

@@ -0,0 +1,142 @@
+#include <stdint.h>
+#include <string>
+#include <iostream>
+#include <sstream>
+
+#include "BlockDecoder.h"
+#include "ZlibDecompressor.h"
+
+static inline uint16_t readU16(const unsigned char *data)
+{
+	return data[0] << 8 | data[1];
+}
+
+static int readBlockContent(const unsigned char *mapData, u8 version, unsigned int datapos)
+{
+	if (version >= 24) {
+		size_t index = datapos << 1;
+		return (mapData[index] << 8) | mapData[index + 1];
+	} else if (version >= 20) {
+		if (mapData[datapos] <= 0x80)
+			return mapData[datapos];
+		else
+			return (int(mapData[datapos]) << 4) | (int(mapData[datapos + 0x2000]) >> 4);
+	}
+	std::ostringstream oss;
+	oss << "Unsupported map version " << version;
+	throw std::runtime_error(oss.str());
+}
+
+BlockDecoder::BlockDecoder()
+{
+	reset();
+}
+
+void BlockDecoder::reset()
+{
+	m_blockAirId = -1;
+	m_blockIgnoreId = -1;
+	m_nameMap.clear();
+
+	m_version = 0;
+	m_mapData = ustring();
+}
+
+void BlockDecoder::decode(const ustring &datastr)
+{
+	const unsigned char *data = datastr.c_str();
+	size_t length = datastr.length();
+	// TODO: bounds checks
+
+	uint8_t version = data[0];
+	//uint8_t flags = data[1];
+	m_version = version;
+
+	size_t dataOffset = 0;
+	if (version >= 27)
+		dataOffset = 6;
+	else if (version >= 22)
+		dataOffset = 4;
+	else
+		dataOffset = 2;
+
+	ZlibDecompressor decompressor(data, length);
+	decompressor.setSeekPos(dataOffset);
+	m_mapData = decompressor.decompress();
+	decompressor.decompress(); // unused metadata
+	dataOffset = decompressor.seekPos();
+
+	// Skip unused data
+	if (version <= 21)
+		dataOffset += 2;
+	if (version == 23)
+		dataOffset += 1;
+	if (version == 24) {
+		uint8_t ver = data[dataOffset++];
+		if (ver == 1) {
+			uint16_t num = readU16(data + dataOffset);
+			dataOffset += 2;
+			dataOffset += 10 * num;
+		}
+	}
+
+	// Skip unused static objects
+	dataOffset++; // Skip static object version
+	int staticObjectCount = readU16(data + dataOffset);
+	dataOffset += 2;
+	for (int i = 0; i < staticObjectCount; ++i) {
+		dataOffset += 13;
+		uint16_t dataSize = readU16(data + dataOffset);
+		dataOffset += dataSize + 2;
+	}
+	dataOffset += 4; // Skip timestamp
+
+	// Read mapping
+	if (version >= 22) {
+		dataOffset++; // mapping version
+		uint16_t numMappings = readU16(data + dataOffset);
+		dataOffset += 2;
+		for (int i = 0; i < numMappings; ++i) {
+			uint16_t nodeId = readU16(data + dataOffset);
+			dataOffset += 2;
+			uint16_t nameLen = readU16(data + dataOffset);
+			dataOffset += 2;
+			std::string name(reinterpret_cast<const char *>(data) + dataOffset, nameLen);
+			if (name == "air")
+				m_blockAirId = nodeId;
+			else if (name == "ignore")
+				m_blockIgnoreId = nodeId;
+			else
+				m_nameMap[nodeId] = name;
+			dataOffset += nameLen;
+		}
+	}
+
+	// Node timers
+	if (version >= 25) {
+		dataOffset++;
+		uint16_t numTimers = readU16(data + dataOffset);
+		dataOffset += 2;
+		dataOffset += numTimers * 10;
+	}
+}
+
+bool BlockDecoder::isEmpty() const
+{
+	// only contains ignore and air nodes?
+	return m_nameMap.empty();
+}
+
+std::string BlockDecoder::getNode(u8 x, u8 y, u8 z) const
+{
+	unsigned int position = x + (y << 4) + (z << 8);
+	int content = readBlockContent(m_mapData.c_str(), m_version, position);
+	if (content == m_blockAirId || content == m_blockIgnoreId)
+		return "";
+	NameMap::const_iterator it = m_nameMap.find(content);
+	if (it == m_nameMap.end()) {
+		std::cerr << "Skipping node with invalid ID." << std::endl;
+		return "";
+	}
+	return it->second;
+}