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: dict_decoder.go
    path of file: ./repos/gccrs/libgo/go/compress/flate
    
    the code of the file until where you have to start completion: // Copyright 2016 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 flate

//
    
func (dd *dictDecoder) writeCopy(dist, length int) int {
	dstBase := dd.wrPos
	dstPos := dstBase
	srcPos := dstPos - dist
	endPos := dstPos + length
	if endPos > len(dd.hist) {
		endPos = len(dd.hist)
	}

	// Copy non-overlapping section after destination position.
	//
	// This section is non-overlapping in that the copy length for this section
	// is always less than or equal to the backwards distance. This can occur
	// if a distance refers to data that wraps-around in the buffer.
	// Thus, a backwards copy is performed here; that is, the exact bytes in
	// the source prior to the copy is placed in the destination.
	if srcPos < 0 {
		srcPos += len(dd.hist)
		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:])
		srcPos = 0
	}

	// Copy possibly overlapping section before destination position.
	//
	// This section can overlap if the copy length for this section is larger
	// than the backwards distance. This is allowed by LZ77 so that repeated
	// strings can be succinctly represented using (dist, length) pairs.
	// Thus, a forwards copy is performed here; that is, the bytes copied is
	// possibly dependent on the resulting bytes in the destination as the copy
	// progresses along. This is functionally equivalent to the following:
	//
	//	for i := 0; i < endPos-dstPos; i++ {
	//		dd.hist[dstPos+i] = dd.hist[srcPos+i]
	//	}
	//	dstPos = endPos
	//
	for dstPos < endPos {
		dstPos += copy(dd.hist[dstPos:endPos], dd.hist[srcPos:dstPos])
	}

	dd.wrPos = dstPos
	return dstPos - dstBase
}