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  1. JDK
  2. JDK-4507868

method writeBits does not advance bit offset

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    • Subcomponent:
    • Resolved In Build:
      hopper
    • CPU:
      generic, x86
    • OS:
      generic, linux

      Description



      Name: ipR10067 Date: 09/27/2001




      Specification of the
      method javax.imageio.stream.ImageOutputStreamImpl.writeBits
      says:

      "public void writeBits(long bits, int numBits) throws IOException

        ... The bit offset is advanced by numBits and reduced modulo 8.
        

      "
      The implementation (JDK 1.4.0beta3, build b80) of the method
      sets current bit offset to numBits instead of advancing by numBits.

      To reproduce the bug run the following test:
      ------------ test.java ------------------------
      import javax.imageio.stream.MemoryCacheImageOutputStream;
      import java.io.ByteArrayOutputStream;
      import java.io.IOException;

      public class test {

          public static void main(String argv[]) {
             ByteArrayOutputStream ostream = new ByteArrayOutputStream();
             MemoryCacheImageOutputStream mcios = new MemoryCacheImageOutputStream(ostream);
             try {
                 for (int i=0; i < 8; i+=2) {
                     mcios.writeBits(3, 2);
                     System.out.println(mcios.getBitOffset());
                 }
             } catch (IOException e) {
                   System.out.println("Unexpected IOException: " + e);
             }
         }

      }

      ------------ Logs -----------------------------
      $ java -version
      java version "1.4.0-beta3"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta3-b80)
      Java HotSpot(TM) Client VM (build 1.4.0-beta3-b80, mixed mode)

      $ javac -d . test.java

      $ java test
      2
      2
      2
      2
      ======================================================================

      This bug affects new JCK test:
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits001]
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits002]
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits003]
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits004]
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits005]
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits006]
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits007]
      api/javax_imageio/stream/ImageOutputStreamImpl/index.html#WriteBits[WriteBits009]

      ======================================================================

      ======================================================================

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            Assignee:
            campbell Christopher Campbell (Inactive)
            Reporter:
            ipsunw Ip Ip (Inactive)
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