hunk.code_window: 				return
   			}
   		}
   	}()
   	time.Sleep(300 * time.Millisecond)
   	stop <- true
  
hunk.labels: keep keep keep keep keep replace keep keep keep
hunk.after_edit: 	time.Sleep(400 * time.Millisecond)
  
hunk.file_path: api/websocket_test.go
hunk.type: replace
file: // 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 vp8l implements a decoder for the VP8L lossless image format.
  //
  // The VP8L specification is at:
  // https://developers.google.com/speed/webp/docs/riff_container
  package vp8l // import "golang.org/x/image/vp8l"
  
  import (
  	"bufio"
  	"errors"
  	"image"
  	"image/color"
  	"io"
  )
  
  var (
  	errInvalidCodeLengths = errors.New("vp8l: invalid code lengths")
  	errInvalidHuffmanTree = errors.New("vp8l: invalid Huffman tree")
  )
  
  // colorCacheMultiplier is the multiplier used for the color cache hash
  // function, specified in section 4.2.3.
  const colorCacheMultiplier = 0x1e35a7bd
  
  // distanceMapTable is the look-up table for distanceMap.
  var distanceMapTable = [120]uint8{
  	0x18, 0x07, 0x17, 0x19, 0x28, 0x06, 0x27, 0x29, 0x16, 0x1a,
  	0x26, 0x2a, 0x38, 0x05, 0x37, 0x39, 0x15, 0x1b, 0x36, 0x3a,
  	0x25, 0x2b, 0x48, 0x04, 0x47, 0x49, 0x14, 0x1c, 0x35, 0x3b,
  	0x46, 0x4a, 0x24, 0x2c, 0x58, 0x45, 0x4b, 0x34, 0x3c, 0x03,
  	0x57, 0x59, 0x13, 0x1d, 0x56, 0x5a, 0x23, 0x2d, 0x44, 0x4c,
  	0x55, 0x5b, 0x33, 0x3d, 0x68, 0x02, 0x67, 0x69, 0x12, 0x1e,
  	0x66, 0x6a, 0x22, 0x2e, 0x54, 0x5c, 0x43, 0x4d, 0x65, 0x6b,
  	0x32, 0x3e, 0x78, 0x01, 0x77, 0x79, 0x53, 0x5d, 0x11, 0x1f,
  	0x64, 0x6c, 0x42, 0x4e, 0x76, 0x7a, 0x21, 0x2f, 0x75, 0x7b,
  	0x31, 0x3f, 0x63, 0x6d, 0x52, 0x5e, 0x00, 0x74, 0x7c, 0x41,
  	0x4f, 0x10, 0x20, 0x62, 0x6e, 0x30, 0x73, 0x7d, 0x51, 0x5f,
  	0x40, 0x72, 0x7e, 0x61, 0x6f, 0x50, 0x71, 0x7f, 0x60, 0x70,
  }
  
  // distanceMap maps a LZ77 backwards reference distance to a two-dimensional
  // pixel offset, specified in section 4.2.2.
  func distanceMap(w int32, code uint32) int32 {
  	if int32(code) > int32(len(distanceMapTable)) {
  		return int32(code) - int32(len(distanceMapTable))
  	}
  	distCode := int32(distanceMapTable[code-1])
  	yOffset := distCode >> 4
  	xOffset := 8 - distCode&0xf
  	if d := yOffset*w + xOffset; d >= 1 {
  		return d
  	}
  	return 1
  }
  
  // decoder holds the bit-stream for a VP8L image.
  type decoder struct {
  	r     io.ByteReader
  	bits  uint32
  	nBits uint32
  }
  
  // read reads the next n bits from the decoder's bit-stream.
  func (d *decoder) read(n uint32) (uint32, error) {
  	for d.nBits < n {
  		c, err := d.r.ReadByte()
  		if err != nil {
  			if err == io.EOF {
  				err = io.ErrUnexpectedEOF
  			}
  			return 0, err
  		}
  		d.bits |= uint32(c) << d.nBits
  		d.nBits += 8
  	}
  	u := d.bits & (1<<n - 1)
  	d.bits >>= n
  	d.nBits -= n
  	return u, nil
  }
  
  // decodeTransform decodes the next transform and the width of the image after
  // transformation (or equivalently, before inverse transformation), specified
  // in section 3.
  func (d *decoder) decodeTransform(w int32, h int32) (t transform, newWidth int32, err error) {
  	t.oldWidth = w
  	t.transformType, err = d.read(2)
  	if err != nil {
  		return transform{}, 0, err
  	}
  	switch t.transformType {
  	case transformTypePredictor, transformTypeCrossColor:
  		t.bits, err = d.read(3)
  		if err != nil {
  			return transform{}, 0, err
  		}
  		t.bits += 2
  		t.pix, err = d.decodePix(nTiles(w, t.bits), nTiles(h, t.bits), 0, false)
  		if err != nil {
  			return transform{}, 0, err
  		}
  	case transformTypeSubtractGreen:
  		// No-op.
  	case transformTypeColorIndexing:
  		nColors, err := d.read(8)
  		if err != nil {
  			return transform{}, 0, err
  		}
  		nColors++
  		t.bits = 0
  		switch {
  		case nColors <= 2:
  			t.bits = 3
  		case nColors <= 4:
  			t.bits = 2
  		case nColors <= 16:
  			t.bits = 1
  		}
  		w = nTiles(w, t.bits)
  		pix, err := d.decodePix(int32(nColors), 1, 4*256, false)
  		if err != nil {
  			return transform{}, 0, err
  		}
  		for p := 4; p < len(pix); p += 4 {
  			pix[p+0] += pix[p-4]
  			pix[p+1] += pix[p-3]
  			pix[p+2] += pix[p-2]
  			pix[p+3] += pix[p-1]
  		}
  		// The spec says that "if the index is equal or larger than color_table_size,
  		// the argb color value should be set to 0x00000000 (transparent black)."
  		// We re-slice up to 256 4-byte pixels.
  		t.pix = pix[:4*256]
  	}
  	return t, w, nil
  }
  
  // repeatsCodeLength is the minimum code length for repeated codes.
  const repeatsCodeLength = 16
  
  // These magic numbers are specified at the end of section 5.2.2.
  // The 3-length arrays apply to code lengths >= repeatsCodeLength.
  var (
  	codeLengthCodeOrder = [19]uint8{
  		17, 18, 0, 1, 2, 3, 4, 5, 16, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
  	}
  	repeatBits    = [3]uint8{2, 3, 7}
  	repeatOffsets = [3]uint8{3, 3, 11}
  )
  
  // decodeCodeLengths decodes a Huffman tree's code lengths which are themselves
  // encoded via a Huffman tree, specified in section 5.2.2.
  func (d *decoder) decodeCodeLengths(dst []uint32, codeLengthCodeLengths []uint32) error {
  	h := hTree{}
  	if err := h.build(codeLengthCodeLengths); err != nil {
  		return err
  	}
  
  	maxSymbol := len(dst)
  	useLength, err := d.read(1)
  	if err != nil {
  		return err
  	}
  	if useLength != 0 {
  		n, err := d.read(3)
  		if err != nil {
  			return err
  		}
  		n = 2 + 2*n
  		ms, err := d.read(n)
  		if err != nil {
  			return err
  		}
  		maxSymbol = int(ms) + 2
  		if maxSymbol > len(dst) {
  			return errInvalidCodeLengths
  		}
  	}
  
  	// The spec says that "if code 16 [meaning repeat] is used before
  	// a non-zero value has been emitted, a value of 8 is repeated."
  	prevCodeLength := uint32(8)
  
  	for symbol := 0; symbol < len(dst); {
  		if maxSymbol == 0 {
  			break
  		}
  		maxSymbol--
  		codeLength, err := h.next(d)
  		if err != nil {
  			return err
  		}
  		if codeLength < repeatsCodeLength {
  			dst[symbol] = codeLength
  			symbol++
  			if codeLength != 0 {
  				prevCodeLength = codeLength
  			}
  			continue
  		}
  
  		repeat, err := d.read(uint32(repeatBits[codeLength-repeatsCodeLength]))
  		if err != nil {
  			return err
  		}
  		repeat += uint32(repeatOffsets[codeLength-repeatsCodeLength])
  		if symbol+int(repeat) > len(dst) {
  			return errInvalidCodeLengths
  		}
  		// A code length of 16 repeats the previous non-zero code.
  		// A code length of 17 or 18 repeats zeroes.
  		cl := uint32(0)
  		if codeLength == 16 {
  			cl = prevCodeLength
  		}
  		for ; repeat > 0; repeat-- {
  			dst[symbol] = cl
  			symbol++
  		}
  	}
  	return nil
  }
  
  // decodeHuffmanTree decodes a Huffman tree into h.
  func (d *decoder) decodeHuffmanTree(h *hTree, alphabetSize uint32) error {
  	useSimple, err := d.read(1)
  	if err != nil {
  		return err
  	}
  	if useSimple != 0 {
  		nSymbols, err := d.read(1)
  		if err != nil {
  			return err
  		}
  		nSymbols++
  		firstSymbolLengthCode, err := d.read(1)
  		if err != nil {
  			return err
  		}
  		firstSymbolLengthCode = 7*firstSymbolLengthCode + 1
  		var symbols [2]uint32
  		symbols[0], err = d.read(firstSymbolLengthCode)
  		if err != nil {
  			return err
  		}
  		if nSymbols == 2 {
  			symbols[1], err = d.read(8)
  			if err != nil {
  				return err
  			}
  		}
  		return h.buildSimple(nSymbols, symbols, alphabetSize)
  	}
  
  	nCodes, err := d.read(4)
  	if err != nil {
  		return err
  	}
  	nCodes += 4
  	if int(nCodes) > len(codeLengthCodeOrder) {
  		return errInvalidHuffmanTree
  	}
  	codeLengthCodeLengths := [len(codeLengthCodeOrder)]uint32{}
  	for i := uint32(0); i < nCodes; i++ {
  		codeLengthCodeLengths[codeLengthCodeOrder[i]], err = d.read(3)
  		if err != nil {
  			return err
  		}
  	}
  	codeLengths := make([]uint32, alphabetSize)
  	if err = d.decodeCodeLengths(codeLengths, codeLengthCodeLengths[:]); err != nil {
  		return err
  	}
  	return h.build(codeLengths)
  }
  
  const (
  	huffGreen    = 0
  	huffRed      = 1
  	huffBlue     = 2
  	huffAlpha    = 3
  	huffDistance = 4
  	nHuff        = 5
  )
  
  // hGroup is an array of 5 Huffman trees.
  type hGroup [nHuff]hTree
  
  // decodeHuffmanGroups decodes the one or more hGroups used to decode the pixel
  // data. If one hGroup is used for the entire image, then hPix and hBits will
  // be zero. If more than one hGroup is used, then hPix contains the meta-image
  // that maps tiles to hGroup index, and hBits contains the log-2 tile size.
  func (d *decoder) decodeHuffmanGroups(w int32, h int32, topLevel bool, ccBits uint32) (
  	hGroups []hGroup, hPix []byte, hBits uint32, err error) {
  
  	maxHGroupIndex := 0
  	if topLevel {
  		useMeta, err := d.read(1)
  		if err != nil {
  			return nil, nil, 0, err
  		}
  		if useMeta != 0 {
  			hBits, err = d.read(3)
  			if err != nil {
  				return nil, nil, 0, err
  			}
  			hBits += 2
  			hPix, err = d.decodePix(nTiles(w, hBits), nTiles(h, hBits), 0, false)
  			if err != nil {
  				return nil, nil, 0, err
  			}
  			for p := 0; p < len(hPix); p += 4 {
  				i := int(hPix[p])<<8 | int(hPix[p+1])
  				if maxHGroupIndex < i {
  					maxHGroupIndex = i
  				}
  			}
  		}
  	}
  	hGroups = make([]hGroup, maxHGroupIndex+1)
  	for i := range hGroups {
  		for j, alphabetSize := range alphabetSizes {
  			if j == 0 && ccBits > 0 {
  				alphabetSize += 1 << ccBits
  			}
  			if err := d.decodeHuffmanTree(&hGroups[i][j], alphabetSize); err != nil {
  				return nil, nil, 0, err
  			}
  		}
  	}
  	return hGroups, hPix, hBits, nil
  }
  
  const (
  	nLiteralCodes  = 256
  	nLengthCodes   = 24
  	nDistanceCodes = 40
  )
  
  var alphabetSizes = [nHuff]uint32{
  	nLiteralCodes + nLengthCodes,
  	nLiteralCodes,
  	nLiteralCodes,
  	nLiteralCodes,
  	nDistanceCodes,
  }
  
  // decodePix decodes pixel data, specified in section 5.2.2.
  func (d *decoder) decodePix(w int32, h int32, minCap int32, topLevel bool) ([]byte, error) {
  	// Decode the color cache parameters.
  	ccBits, ccShift, ccEntries := uint32(0), uint32(0), ([]uint32)(nil)
  	useColorCache, err := d.read(1)
  	if err != nil {
  		return nil, err
  	}
  	if useColorCache != 0 {
  		ccBits, err = d.read(4)
  		if err != nil {
  			return nil, err
  		}
  		if ccBits < 1 || 11 < ccBits {
  			return nil, errors.New("vp8l: invalid color cache parameters")
  		}
  		ccShift = 32 - ccBits
  		ccEntries = make([]uint32, 1<<ccBits)
  	}
  
  	// Decode the Huffman groups.
  	hGroups, hPix, hBits, err := d.decodeHuffmanGroups(w, h, topLevel, ccBits)
  	if err != nil {
  		return nil, err
  	}
  	hMask, tilesPerRow := int32(0), int32(0)
  	if hBits != 0 {
  		hMask, tilesPerRow = 1<<hBits-1, nTiles(w, hBits)
  	}
  
  	// Decode the pixels.
  	if minCap < 4*w*h {
  		minCap = 4 * w * h
  	}
  	pix := make([]byte, 4*w*h, minCap)
  	p, cachedP := 0, 0
  	x, y := int32(0), int32(0)
  	hg, lookupHG := &hGroups[0], hMask != 0
  	for p < len(pix) {
  		if lookupHG {
  			i := 4 * (tilesPerRow*(y>>hBits) + (x >> hBits))
  			hg = &hGroups[uint32(hPix[i])<<8|uint32(hPix[i+1])]
  		}
  
  		green, err := hg[huffGreen].next(d)
  		if err != nil {
  			return nil, err
  		}
  		switch {
  		case green < nLiteralCodes:
  			// We have a literal pixel.
  			red, err := hg[huffRed].next(d)
  			if err != nil {
  				return nil, err
  			}
  			blue, err := hg[huffBlue].next(d)
  			if err != nil {
  				return nil, err
  			}
  			alpha, err := hg[huffAlpha].next(d)
  			if err != nil {
  				return nil, err
  			}
  			pix[p+0] = uint8(red)
  			pix[p+1] = uint8(green)
  			pix[p+2] = uint8(blue)
  			pix[p+3] = uint8(alpha)
  			p += 4
  
  			x++
  			if x == w {
  				x, y = 0, y+1
  			}
  			lookupHG = hMask != 0 && x&hMask == 0
  
  		case green < nLiteralCodes+nLengthCodes:
  			// We have a LZ77 backwards reference.
  			length, err := d.lz77Param(green - nLiteralCodes)
  			if err != nil {
  				return nil, err
  			}
  			distSym, err := hg[huffDistance].next(d)
  			if err != nil {
  				return nil, err
  			}
  			distCode, err := d.lz77Param(distSym)
  			if err != nil {
  				return nil, err
  			}
  			dist := distanceMap(w, distCode)
  			pEnd := p + 4*int(length)
  			q := p - 4*int(dist)
  			qEnd := pEnd - 4*int(dist)
  			if p < 0 || len(pix) < pEnd || q < 0 || len(pix) < qEnd {
  				return nil, errors.New("vp8l: invalid LZ77 parameters")
  			}
  			for ; p < pEnd; p, q = p+1, q+1 {
  				pix[p] = pix[q]
  			}
  
  			x += int32(length)
  			for x >= w {
  				x, y = x-w, y+1
  			}
  			lookupHG = hMask != 0
  
  		default:
  			// We have a color cache lookup. First, insert previous pixels
  			// into the cache. Note that VP8L assumes ARGB order, but the
  			// Go image.RGBA type is in RGBA order.
  			for ; cachedP < p; cachedP += 4 {
  				argb := uint32(pix[cachedP+0])<<16 |
  					uint32(pix[cachedP+1])<<8 |
  					uint32(pix[cachedP+2])<<0 |
  					uint32(pix[cachedP+3])<<24
  				ccEntries[(argb*colorCacheMultiplier)>>ccShift] = argb
  			}
  			green -= nLiteralCodes + nLengthCodes
  			if int(green) >= len(ccEntries) {
  				return nil, errors.New("vp8l: invalid color cache index")
  			}
  			argb := ccEntries[green]
  			pix[p+0] = uint8(argb >> 16)
  			pix[p+1] = uint8(argb >> 8)
  			pix[p+2] = uint8(argb >> 0)
  			pix[p+3] = uint8(argb >> 24)
  			p += 4
  
  			x++
  			if x == w {
  				x, y = 0, y+1
  			}
  			lookupHG = hMask != 0 && x&hMask == 0
  		}
  	}
  	return pix, nil
  }
  
  // lz77Param returns the next LZ77 parameter: a length or a distance, specified
  // in section 4.2.2.
  func (d *decoder) lz77Param(symbol uint32) (uint32, error) {
  	if symbol < 4 {
  		return symbol + 1, nil
  	}
  	extraBits := (symbol - 2) >> 1
  	offset := (2 + symbol&1) << extraBits
  	n, err := d.read(extraBits)
  	if err != nil {
  		return 0, err
  	}
  	return offset + n + 1, nil
  }
  
  // decodeHeader decodes the VP8L header from r.
  func decodeHeader(r io.Reader) (d *decoder, w int32, h int32, err error) {
  	rr, ok := r.(io.ByteReader)
  	if !ok {
  		rr = bufio.NewReader(r)
  	}
  	d = &decoder{r: rr}
  	magic, err := d.read(8)
  	if err != nil {
  		return nil, 0, 0, err
  	}
  	if magic != 0x2f {
  		return nil, 0, 0, errors.New("vp8l: invalid header")
  	}
  	width, err := d.read(14)
  	if err != nil {
  		return nil, 0, 0, err
  	}
  	width++
  	height, err := d.read(14)
  	if err != nil {
  		return nil, 0, 0, err
  	}
  	height++
  	_, err = d.read(1) // Read and ignore the hasAlpha hint.
  	if err != nil {
  		return nil, 0, 0, err
  	}
  	version, err := d.read(3)
  	if err != nil {
  		return nil, 0, 0, err
  	}
  	if version != 0 {
  		return nil, 0, 0, errors.New("vp8l: invalid version")
  	}
  	return d, int32(width), int32(height), nil
  }
  
  // DecodeConfig decodes the color model and dimensions of a VP8L image from r.
  func DecodeConfig(r io.Reader) (image.Config, error) {
  	_, w, h, err := decodeHeader(r)
  	if err != nil {
  		return image.Config{}, err
  	}
  	return image.Config{
  		ColorModel: color.NRGBAModel,
  		Width:      int(w),
  		Height:     int(h),
  	}, nil
  }
  
  // Decode decodes a VP8L image from r.
  func Decode(r io.Reader) (image.Image, error) {
  	d, w, h, err := decodeHeader(r)
  	if err != nil {
  		return nil, err
  	}
  	// Decode the transforms.
  	var (
  		nTransforms    int
  		transforms     [nTransformTypes]transform
  		transformsSeen [nTransformTypes]bool
  		originalW      = w
  	)
  	for {
  		more, err := d.read(1)
  		if err != nil {
  			return nil, err
  		}
  		if more == 0 {
  			break
  		}
  		var t transform
  		t, w, err = d.decodeTransform(w, h)
  		if err != nil {
  			return nil, err
  		}
  		if transformsSeen[t.transformType] {
  			return nil, errors.New("vp8l: repeated transform")
  		}
  		transformsSeen[t.transformType] = true
  		transforms[nTransforms] = t
  		nTransforms++
  	}
  	// Decode the transformed pixels.
  	pix, err := d.decodePix(w, h, 0, true)
  	if err != nil {
  		return nil, err
  	}
  	// Apply the inverse transformations.
  	for i := nTransforms - 1; i >= 0; i-- {
  		t := &transforms[i]
  		pix = inverseTransforms[t.transformType](t, pix, h)
  	}
  	return &image.NRGBA{
  		Pix:    pix,
  		Stride: 4 * int(originalW),
  		Rect:   image.Rect(0, 0, int(originalW), int(h)),
  	}, nil
  }
  