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: decode29_ppm.go
    path of file: ./repos/scan4all/vendor/github.com/nwaples/rardecode
    
    the code of the file until where you have to start completion: package rardecode

import "io"

type ppm29Decoder struct {
	m   model // ppm model
	esc byte  // escape character
	br  io.ByteReader
}

func (d *ppm29Decoder) init(br *rarBitReader) error {
	maxOrder, err := br.readBits(7)
	if err != nil {
		return err
	}
	reset := maxOrder&0x20 > 0

	// Should have flushed all unread bits from
    
func (d *ppm29Decoder) decode(w *window) ([]byte, error) {
	c, err := d.m.ReadByte()
	if err != nil {
		return nil, err
	}
	if c != d.esc {
		w.writeByte(c)
		return nil, nil
	}
	c, err = d.m.ReadByte()
	if err != nil {
		return nil, err
	}

	switch c {
	case 0:
		return nil, endOfBlock
	case 2:
		return nil, endOfBlockAndFile
	case 3:
		return d.readFilterData()
	case 4:
		offset := 0
		for i := 0; i < 3; i++ {
			c, err = d.m.ReadByte()
			if err != nil {
				return nil, err
			}
			offset = offset<<8 | int(c)
		}
		len, err := d.m.ReadByte()
		if err != nil {
			return nil, err
		}
		w.copyBytes(int(len)+32, offset+2)
	case 5:
		len, err := d.m.ReadByte()
		if err != nil {
			return nil, err
		}
		w.copyBytes(int(len)+4, 1)
	default:
		w.writeByte(d.esc)
	}
	return nil, nil
}