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: sha3.go
    path of file: ./repos/teller/vendor/github.com/cloudflare/circl/internal/sha3
    
    the code of the file until where you have to start completion: // Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sha3

// spongeDirection indicates the direction bytes are flowing through the sponge.
type spongeDirection int

const (
	// spongeAbsorbing indicates that the sponge is absorbing input.
	spongeAbsorbing spongeDirection = 
    
func (d *State) padAndPermute(dsbyte byte) {
	// Pad with this instance's domain-separator bits. We know that there's
	// at least one byte of space in d.buf() because, if it were full,
	// permute would have been called to empty it. dsbyte also contains the
	// first one bit for the padding. See the comment in the state struct.
	zerosStart := d.bufe + 1
	d.bufe = d.rate
	buf := d.buf()
	buf[zerosStart-1] = dsbyte
	for i := zerosStart; i < d.rate; i++ {
		buf[i] = 0
	}
	// This adds the final one bit for the padding. Because of the way that
	// bits are numbered from the LSB upwards, the final bit is the MSB of
	// the last byte.
	buf[d.rate-1] ^= 0x80
	// Apply the permutation
	d.permute()
	d.state = spongeSqueezing
	d.bufe = d.rate
	copyOut(d, buf)
}