Add zstd library

common/block.go

@@ -10,9 +10,10 @@ import (
 	"encoding/binary"
 	"errors"
 	"io"
-	"io/ioutil"
 	"log"
 	"sync"
+
+	"github.com/klauspost/compress/zstd"
 )
 
 // Error returned if a Producer has run to its end.
@@ -100,88 +101,102 @@ func NewDecodedBlock(data []byte, colors *Colors) (db *DecodedBlock, err error)
 
 	version := data[0]
 
-	contentWidth := Min(int(data[2]), 2)
-	paramsWidth := Min(int(data[3]), 2)
-
-	uncompressedLen := nodeCount * (contentWidth + paramsWidth)
-
+	//var mapContent := make([]byte, uncompressedLen)
+	var mapContent []byte
 	var offset int
-	switch {
-	case version >= 27:
-		offset = 6
-	case version >= 22:
-		offset = 4
-	default:
-		offset = 2
-	}
 
-	zr := zlibReaderPool.Get().(interface {
-		io.ReadCloser
-		zlib.Resetter
-	})
-	defer func() {
-		zr.Close() // This sould not be necessary.
-		zlibReaderPool.Put(zr)
-	}()
+	if version >= 29 {
+		dec, err := zstd.NewReader(nil)
+		if err != nil {
+			return nil, err
+		}
+		mapContent, err = dec.DecodeAll(data[1:], nil)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		contentWidth := Min(int(data[2]), 2)
+		paramsWidth := Min(int(data[3]), 2)
 
-	buf := posBuf{Data: data[offset:]}
-	if err = zr.Reset(&buf, nil); err != nil {
-		return
-	}
+		uncompressedLen := nodeCount * (contentWidth + paramsWidth)
 
-	mapContent := make([]byte, uncompressedLen)
+		switch {
+		case version >= 27:
+			offset = 6
+		case version >= 22:
+			offset = 4
+		default:
+			offset = 2
+		}
 
-	var k int
-	k, err = io.ReadFull(zr, mapContent)
-	if err != nil {
-		return
-	}
+		zr := zlibReaderPool.Get().(interface {
+			io.ReadCloser
+			zlib.Resetter
+		})
+		defer func() {
+			zr.Close() // This sould not be necessary.
+			zlibReaderPool.Put(zr)
+		}()
 
-	if k != uncompressedLen {
-		err = ErrMapContentSizeMismatch
-		return
-	}
+		buf := posBuf{Data: data[offset:]}
+		if err = zr.Reset(&buf, nil); err != nil {
+			return
+		}
 
-	// There is a bug before Go 1.7 that enforces
-	// to add 4 as an offset after the compressed
-	// geometry data. This is resolved via build tags
-	// and definitions in pre17offset.go and
-	// post17offset.go.
-	offset += buf.Pos + afterCompressOfs
-	buf.Pos = 0
-	if offset >= dataLen {
-		return nil, ErrBlockTruncated
-	}
-	buf.Data = data[offset:]
+		mapContent = make([]byte, uncompressedLen)
 
-	if err = zr.(zlib.Resetter).Reset(&buf, nil); err != nil {
-		return
-	}
+		var k int
+		k, err = io.ReadFull(zr, mapContent)
+		if err != nil {
+			return
+		}
 
-	// Discard the meta data.
-	if _, err = io.Copy(ioutil.Discard, zr); err != nil {
-		return
-	}
+		if k != uncompressedLen {
+			err = ErrMapContentSizeMismatch
+			return
+		}
 
-	offset += buf.Pos
-
-	switch {
-	case version <= 21:
-		offset += 2
-	case version == 23:
-		offset++
-	case version == 24:
+		// There is a bug before Go 1.7 that enforces
+		// to add 4 as an offset after the compressed
+		// geometry data. This is resolved via build tags
+		// and definitions in pre17offset.go and
+		// post17offset.go.
+		offset += buf.Pos + afterCompressOfs
+		buf.Pos = 0
 		if offset >= dataLen {
 			return nil, ErrBlockTruncated
 		}
-		ver := data[offset]
-		offset++
-		if ver == 1 {
-			if offset+1 >= dataLen {
+		buf.Data = data[offset:]
+
+		if err = zr.(zlib.Resetter).Reset(&buf, nil); err != nil {
+			return
+		}
+
+		// Discard the meta data.
+		if _, err = io.Copy(io.Discard, zr); err != nil {
+			return
+		}
+
+		offset += buf.Pos
+
+		switch {
+		case version <= 21:
+			offset += 2
+		case version == 23:
+			offset++
+		case version == 24:
+			if offset >= dataLen {
 				return nil, ErrBlockTruncated
 			}
-			num := int(binary.BigEndian.Uint16(data[offset:]))
-			offset += 2 + 10*num
+			ver := data[offset]
+			offset++
+			if ver == 1 {
+				if offset+1 >= dataLen {
+					return nil, ErrBlockTruncated
+				}
+				num := int(binary.BigEndian.Uint16(data[offset:]))
+				offset += 2 + 10*num
+			}
 		}
 	}