Parse chunk data on demand

src/Buffer.hpp

@@ -40,34 +40,47 @@ private:
 	size_t len;
 
 public:
+	static uint16_t parse16(const uint8_t *buf) {
+		return (buf[0] << 8) | buf[1];
+	}
+
+	static uint32_t parse32(const uint8_t *buf) {
+		return (uint32_t(buf[0]) << 24) | (uint32_t(buf[1]) << 16) | (uint32_t(buf[2]) << 8) | uint32_t(buf[3]);
+	}
+
+	static uint64_t parse64(const uint8_t *buf) {
+		return (uint64_t(buf[0]) << 56) | (uint64_t(buf[1]) << 48) | (uint64_t(buf[2]) << 40) | (uint64_t(buf[3]) << 32)
+			| (uint64_t(buf[4]) << 24) | (uint64_t(buf[5]) << 16) | (uint64_t(buf[6]) << 8) | uint64_t(buf[7]);
+	}
+
+
 	Buffer(const uint8_t *data0, size_t len0) : data(data0), len(len0) {}
 
-	uint8_t get() {
+	const uint8_t * get(size_t n) {
-		if (!len)
-			throw std::runtime_error("Buffer::get(): buffer underrun");
-
-		data++;
-		len--;
-		return data[-1];
-	}
-
-	std::string getString(size_t n) {
 		if (n > len)
 			throw std::runtime_error("Buffer::get(): buffer underrun");
 
 		data += n;
 		len -= n;
-		return std::string(reinterpret_cast<const char *>(data - n), n);
+		return (data - n);
 	}
 
-	void getData(void *buf, size_t n) {
+	uint8_t get8() {
-		if (n > len)
+		return *get(1);
-			throw std::runtime_error("Buffer::get(): buffer underrun");
-
-		data += n;
-		len -= n;
-		std::memcpy(buf, data - n, n);
 	}
+
+	uint16_t get16() {
+		return parse16(get(2));
+	}
+
+	uint32_t get32() {
+		return parse32(get(4));
+	}
+
+	uint64_t get64() {
+		return parse64(get(8));
+	}
+
 };
 
 }

src/NBT/ByteArrayTag.hpp

@@ -38,22 +38,26 @@ class ByteArrayTag : public Tag {
 private:
 	friend class Tag;
 
-	std::vector<uint8_t> value;
+	uint32_t len;
+	const uint8_t *value;
 
 	ByteArrayTag(Buffer *buffer) {
-		uint32_t len = uint32_t(buffer->get()) << 24;
+		len = buffer->get32();
-		len |= uint32_t(buffer->get()) << 16;
+		value = buffer->get(len);
-		len |= uint32_t(buffer->get()) << 8;
-		len |= uint32_t(buffer->get());
-
-		value.resize(len);
-		buffer->getData(value.data(), len);
 	}
 
 public:
 	virtual Type getType() const {
 		return Type::ByteArray;
 	}
+
+	uint32_t getLength() const {
+		return len;
+	}
+
+	const uint8_t & operator[](size_t i) const {
+		return value[i];
+	}
 };
 
 }

src/NBT/ByteTag.hpp

@@ -39,7 +39,7 @@ private:
 	uint8_t value;
 
 	ByteTag(Buffer *buffer) {
-		value = buffer->get();
+		value = buffer->get8();
 	}
 
 public:

src/NBT/DoubleTag.hpp

@@ -36,17 +36,10 @@ class DoubleTag : public Tag {
 private:
 	friend class Tag;
 
-	DoubleTag(Buffer *buffer) {
+	const uint8_t *ptr;
-		uint64_t value;
 
-		value = uint64_t(buffer->get()) << 56;
+	DoubleTag(Buffer *buffer) {
-		value |= uint64_t(buffer->get()) << 48;
+		ptr = buffer->get(8);
-		value |= uint64_t(buffer->get()) << 40;
-		value |= uint64_t(buffer->get()) << 32;
-		value |= uint64_t(buffer->get()) << 24;
-		value |= uint64_t(buffer->get()) << 16;
-		value |= uint64_t(buffer->get()) << 8;
-		value |= uint64_t(buffer->get());
 	}
 
 public:

src/NBT/FloatTag.hpp

@@ -36,13 +36,10 @@ class FloatTag : public Tag {
 private:
 	friend class Tag;
 
-	FloatTag(Buffer *buffer) {
+	const uint8_t *ptr;
-		uint32_t value;
 
-		value = uint32_t(buffer->get()) << 24;
+	FloatTag(Buffer *buffer) {
-		value |= uint32_t(buffer->get()) << 16;
+		ptr = buffer->get(4);
-		value |= uint32_t(buffer->get()) << 8;
-		value |= uint32_t(buffer->get());
 	}
 
 public:

src/NBT/IntArrayTag.hpp

@@ -38,24 +38,12 @@ class IntArrayTag : public Tag {
 private:
 	friend class Tag;
 
-	std::vector<uint32_t> value;
+	uint32_t len;
+	const uint8_t *ptr;
 
 	IntArrayTag(Buffer *buffer) {
-		uint32_t len = uint32_t(buffer->get()) << 24;
+		len = buffer->get32();
-		len |= uint32_t(buffer->get()) << 16;
+		ptr = buffer->get(4*len);
-		len |= uint32_t(buffer->get()) << 8;
-		len |= uint32_t(buffer->get());
-
-		value.resize(len);
-
-		for (uint32_t i = 0; i < len; i++) {
-			uint32_t v = uint32_t(buffer->get()) << 24;
-			v |= uint32_t(buffer->get()) << 16;
-			v |= uint32_t(buffer->get()) << 8;
-			v |= uint32_t(buffer->get());
-
-			value[i] = v;
-		}
 	}
 
 public:

src/NBT/IntTag.hpp

@@ -36,13 +36,10 @@ class IntTag : public Tag {
 private:
 	friend class Tag;
 
-	uint32_t value;
+	const uint8_t *ptr;
 
 	IntTag(Buffer *buffer) {
-		value = uint32_t(buffer->get()) << 24;
+		ptr = buffer->get(4);
-		value |= uint32_t(buffer->get()) << 16;
-		value |= uint32_t(buffer->get()) << 8;
-		value |= uint32_t(buffer->get());
 	}
 
 public:
@@ -51,7 +48,7 @@ public:
 	}
 
 	uint32_t getValue() const {
-		return value;
+		return Buffer::parse32(ptr);
 	}
 };
 

src/NBT/ListTag.hpp

@@ -53,10 +53,7 @@ private:
 	Type type;
 
 	ListTag(Type type0, Buffer *buffer) : type(type0) {
-		uint32_t len = uint32_t(buffer->get()) << 24;
+		uint32_t len = buffer->get32();
-		len |= uint32_t(buffer->get()) << 16;
-		len |= uint32_t(buffer->get()) << 8;
-		len |= uint32_t(buffer->get());
 
 		this->resize(len);
 

src/NBT/LongTag.hpp

@@ -36,17 +36,10 @@ class LongTag : public Tag {
 private:
 	friend class Tag;
 
-	uint64_t value;
+	const uint8_t *ptr;
 
 	LongTag(Buffer *buffer) {
-		value = uint64_t(buffer->get()) << 56;
+		ptr = buffer->get(8);
-		value |= uint64_t(buffer->get()) << 48;
-		value |= uint64_t(buffer->get()) << 40;
-		value |= uint64_t(buffer->get()) << 32;
-		value |= uint64_t(buffer->get()) << 24;
-		value |= uint64_t(buffer->get()) << 16;
-		value |= uint64_t(buffer->get()) << 8;
-		value |= uint64_t(buffer->get());
 	}
 
 public:
@@ -55,7 +48,7 @@ public:
 	}
 
 	uint64_t getValue() const {
-		return value;
+		return Buffer::parse64(ptr);
 	}
 };
 

src/NBT/ShortTag.hpp

@@ -36,11 +36,10 @@ class ShortTag : public Tag {
 private:
 	friend class Tag;
 
-	uint16_t value;
+	const uint8_t *ptr;
 
 	ShortTag(Buffer *buffer) {
-		value = buffer->get() << 8;
+		ptr = buffer->get(2);
-		value |= buffer->get();
 	}
 
 public:
@@ -49,7 +48,7 @@ public:
 	}
 
 	uint16_t getValue() const {
-		return value;
+		return Buffer::parse16(ptr);
 	}
 };
 

src/NBT/StringTag.hpp

@@ -36,23 +36,18 @@ class StringTag : public Tag {
 private:
 	friend class Tag;
 
-	std::string value;
+	uint16_t len;
+	const uint8_t *ptr;
 
 	StringTag(Buffer *buffer) {
-		uint16_t len = buffer->get() << 8;
+		len = buffer->get16();
-		len |= buffer->get();
+		ptr = buffer->get(len);
-
-		value = buffer->getString(len);
 	}
 
 public:
 	virtual Type getType() const {
 		return Type::String;
 	}
-
-	const std::string & getValue() const {
-		return value;
-	}
 };
 
 }

src/NBT/Tag.cpp

@@ -90,7 +90,7 @@ std::shared_ptr<const Tag> Tag::readTag(Type type, Buffer *buffer) {
 }
 
 std::shared_ptr<const Tag> Tag::readList(Buffer *buffer) {
-	Type type = static_cast<Type>(buffer->get());
+	Type type = static_cast<Type>(buffer->get8());
 
 	switch (type) {
 	case Type::End:
@@ -135,13 +135,12 @@ std::shared_ptr<const Tag> Tag::readList(Buffer *buffer) {
 }
 
 std::pair<std::string, std::shared_ptr<const Tag>> Tag::readNamedTag(Buffer *buffer) {
-	Type type = static_cast<Type>(buffer->get());
+	Type type = static_cast<Type>(buffer->get8());
 	if (type == Type::End)
 		return std::make_pair("", std::shared_ptr<EndTag>(new EndTag()));
 
-	uint16_t len = buffer->get() << 8;
+	uint16_t len = buffer->get16();
-	len |= buffer->get();
+	std::string name(reinterpret_cast<const char*>(buffer->get(len)), len);
-	std::string name = buffer->getString(len);
 
 	return std::make_pair(name, readTag(type, buffer));
 }

src/World/Chunk.cpp

@@ -82,7 +82,6 @@ Chunk::Chunk(uint8_t *buffer, size_t buflen) {
 	if (format != 2)
 		throw std::invalid_argument("unknown chunk format");
 
-	UniqueCPtr<uint8_t[]> data;
 	size_t len;
 	std::tie(data, len) = inflateChunk(buffer+5, size-1);
 

src/World/Chunk.hpp

@@ -43,6 +43,8 @@ public:
 	static const size_t SIZE = 16;
 
 private:
+	UniqueCPtr<uint8_t[]> data;
+
 	static std::pair<UniqueCPtr<uint8_t[]>, size_t> inflateChunk(uint8_t *data, size_t len);
 
 	std::shared_ptr<const NBT::ListTag<NBT::CompoundTag>> sections;