func (e *fastEncoder) Block() *blockEnc {
	return e.blk
}
Block returns the current block.
package zstd
import (
	"math/bits"
	"github.com/klauspost/compress/zstd/internal/xxhash"
)
const (
	tableBits      = 15              
	tableSize      = 1 << tableBits  
	tableMask      = tableSize - 1   
	maxMatchLength = 131074
)
type tableEntry struct {
	val    uint32
	offset int32
}
type fastEncoder struct {
	o encParams
	cur int32
	maxMatchOff int32
	hist        []byte
	crc         *xxhash.Digest
	table       [tableSize]tableEntry
	tmp         [8]byte
	blk         *blockEnc
}
func (e *fastEncoder) CRC() *xxhash.Digest {
	return e.crc
}
func (e *fastEncoder) AppendCRC(dst []byte) []byte {
	crc := e.crc.Sum(e.tmp[:0])
	dst = append(dst, crc[7], crc[6], crc[5], crc[4])
	return dst
}
func (e *fastEncoder) WindowSize(size int) int32 {
	if size > 0 && size < int(e.maxMatchOff) {
		b := int32(1) << uint(bits.Len(uint(size)))
		if b < 1024 {
			b = 1024
		}
		return b
	}
	return e.maxMatchOff
}