func (e *fastEncoder) CRC() *xxhash.Digest {
	return e.crc
}
CRC returns the underlying CRC writer.
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
}