func NewPackedTable() *PackedTable {
	return &PackedTable{}
}
NewPackedTable return a packedTable
package cuckoo
import (
	"bytes"
	"encoding/binary"
	"fmt"
	"io"
	"math/rand"
)
type PackedTable struct {
	kDirBitsPerTag  uint
	kBitsPerBucket  uint
	kBytesPerBucket uint
	kDirBitsMask    uint32
	bitsPerTag      uint
	len        uint
	numBuckets uint
	buckets    []byte
	perm       PermEncoding
}