minetestmapper/BlockDecoder.cpp

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2018-03-25 15:19:48 +02:00
#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;
}