You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: fast_encoder.go
    path of file: ./repos/plumber/vendor/github.com/klauspost/compress/flate
    
    the code of the file until where you have to start completion: // Copyright 2011 The Snappy-Go Authors. All rights reserved.
// Modified for deflate by Klaus Post (c) 2015.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package flate

import (
	"encoding/binary"
	"fmt"
	"math/bi
    
func matchLen(a, b []byte) int {
	var checked int

	for len(a) >= 8 {
		if diff := binary.LittleEndian.Uint64(a) ^ binary.LittleEndian.Uint64(b); diff != 0 {
			return checked + (bits.TrailingZeros64(diff) >> 3)
		}
		checked += 8
		a = a[8:]
		b = b[8:]
	}
	b = b[:len(a)]
	for i := range a {
		if a[i] != b[i] {
			return i + checked
		}
	}
	return len(a) + checked
}