code review 147380043: compress/*: note that NewReader may introduce buffering

src/compress/bzip2/bzip2.go

 // Copyright 2011 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 bzip2 implements bzip2 decompression.
 package bzip2
 
 import "io"
 
 // There's no RFC for bzip2. I used the Wikipedia page for reference and a lot
@@ skipping 24 matching lines @@
         tPos         uint32    // Index of the next output byte in tt.
 
         preRLE      []uint32 // contains the RLE data still to be processed.
         preRLEUsed  int      // number of entries of preRLE used.
         lastByte    int      // the last byte value seen.
         byteRepeats uint     // the number of repeats of lastByte seen.
         repeats     uint     // the number of copies of lastByte to output.
 }
 
 // NewReader returns an io.Reader which decompresses bzip2 data from r.
+// If r does not also implement io.ByteReader,
+// the decompressor may read more data than necessary from r.
 func NewReader(r io.Reader) io.Reader {
         bz2 := new(reader)
         bz2.br = newBitReader(r)
         return bz2
 }
 
 const bzip2FileMagic = 0x425a // "BZ"
 const bzip2BlockMagic = 0x314159265359
 const bzip2FinalMagic = 0x177245385090
 
@@ skipping 437 matching lines @@
 
 // updateCRC updates the crc value to incorporate the data in b.
 // The initial value is 0.
 func updateCRC(val uint32, b []byte) uint32 {
         crc := ^val
         for _, v := range b {
                 crc = crctab[byte(crc>>24)^v] ^ (crc << 8)
         }
         return ^crc
 }