Added simple block decoder for tilemapper.

tilemapper/blockdecoder.go

@@ -0,0 +1,170 @@
+// Copyright 2014 by Sascha L. Teichmann
+// Use of this source code is governed by the MIT license
+// that can be found in the LICENSE file.
+
+package main
+
+import (
+	"compress/zlib"
+	"encoding/binary"
+	"errors"
+	"io"
+	"io/ioutil"
+)
+
+var (
+	ErrMapContentSizeMismatch = errors.New("Content size does not match.")
+)
+
+const (
+	mapBlockSize = 16
+	nodeCount    = mapBlockSize * mapBlockSize * mapBlockSize
+)
+
+type DecodedBlock struct {
+	Version    byte
+	MapContent []byte
+	AirId      int
+	IgnoreId   int
+	NameMap    map[int]string
+}
+
+type PosBuf struct {
+	Data []byte
+	Pos  int
+}
+
+func NewDecodedBlock(data []byte) (db *DecodedBlock, err error) {
+	version := data[0]
+
+	contentWidth := int(data[2])
+	paramsWidth := int(data[3])
+
+	uncompressedLen := nodeCount * (contentWidth + paramsWidth)
+
+	offset := 2
+	if version >= 22 {
+		offset = 4
+	}
+
+	buf := NewPosBuf(data[offset:])
+	var zr io.ReadCloser
+	if zr, err = zlib.NewReader(buf); err != nil {
+		return
+	}
+
+	var mapContent []byte
+	if mapContent, err = ioutil.ReadAll(zr); err != nil {
+		return
+	}
+	zr.Close()
+
+	if uncompressedLen != len(mapContent) {
+		err = ErrMapContentSizeMismatch
+		return
+	}
+
+	offset += buf.Pos
+	buf.Pos = 0
+	buf.Data = data[offset:]
+
+	if zr, err = zlib.NewReader(buf); err != nil {
+		return
+	}
+
+	// Discard the meta data.
+	_, err = io.Copy(ioutil.Discard, zr)
+	zr.Close()
+	if err != nil {
+		return
+	}
+
+	offset += buf.Pos
+
+	switch {
+	case version <= 21:
+		offset += 2
+	case version == 23:
+		offset++
+	case version == 24:
+		ver := data[offset]
+		offset++
+		if ver == 1 {
+			num := int(binary.BigEndian.Uint16(data[offset:]))
+			offset += 2 + 10*num
+		}
+	}
+
+	offset++
+	numStaticObjects := int(binary.BigEndian.Uint16(data[offset:]))
+	offset += 2
+	for i := 0; i < numStaticObjects; i++ {
+		offset += 13
+		dataSize := int(binary.BigEndian.Uint16(data[offset:]))
+		offset += dataSize + 2
+	}
+	offset += 4
+
+	airId, ignoreId := -1, -1
+	nameMap := make(map[int]string)
+	if version >= 22 {
+		offset++
+		numMappings := int(binary.BigEndian.Uint16(data[offset:]))
+		offset += 2
+		for i := 0; i < numMappings; i++ {
+			nodeId := int(binary.BigEndian.Uint16(data[offset:]))
+			offset += 2
+			nameLen := int(binary.BigEndian.Uint16(data[offset:]))
+			offset += 2
+			name := string(data[offset : offset+nameLen])
+			offset += nameLen
+			switch name {
+			case "air":
+				airId = nodeId
+			case "ignore":
+				ignoreId = nodeId
+			default:
+				nameMap[nodeId] = name
+			}
+		}
+	}
+
+	db = &DecodedBlock{
+		Version:    version,
+		MapContent: mapContent,
+		AirId:      airId,
+		IgnoreId:   ignoreId,
+		NameMap:    nameMap}
+
+	return
+}
+
+func NewPosBuf(data []byte) *PosBuf {
+	return &PosBuf{Data: data}
+}
+
+func (pb *PosBuf) Read(p []byte) (int, error) {
+	pl := len(p)
+	ml := len(pb.Data)
+	if pb.Pos >= ml {
+		return 0, io.EOF
+	}
+	rest := ml - pb.Pos
+	if pl > rest {
+		copy(p, pb.Data[pb.Pos:])
+		pb.Pos = ml
+		return rest, io.EOF
+	}
+	copy(p, pb.Data[pb.Pos:pb.Pos+pl])
+	pb.Pos += pl
+	return pl, nil
+}
+
+func (pb *PosBuf) ReadByte() (byte, error) {
+	if pb.Pos >= len(pb.Data) {
+		return 0, io.EOF
+	}
+	c := pb.Data[pb.Pos]
+	pb.Pos++
+	return c, nil
+}

tilemapper/main.go

@@ -65,9 +65,16 @@ func main() {
 	numBlocks := 0
 	bytesTotal := int64(0)
 
+	versions := make(map[byte]int)
+
 	count := func(block *common.Block) {
 		numBlocks++
 		bytesTotal += int64(len(block.Data))
+		if db, err := NewDecodedBlock(block.Data); err == nil {
+			versions[db.Version]++
+		} else {
+			log.Printf("WARN: Decoding block failed: %s", err)
+		}
 	}
 
 	if err = client.QueryCuboid(cuboid, count); err != nil {
@@ -76,4 +83,8 @@ func main() {
 
 	fmt.Printf("num of blocks: %d\n", numBlocks)
 	fmt.Printf("num of bytes: %d\n", bytesTotal)
+
+	for version, count := range versions {
+		fmt.Printf("%d: %d\n", version, count)
+	}
 }