code review 143610043: go.image/vp8l: follow the default code length.

vp8l/decode.go

 // 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
 
@@ skipping 162 matching lines @@
                 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 {
@@ skipping 397 matching lines @@
         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
 }