HexEdit - Window Binary File Editor

<?xml version="1.0"?>
<!DOCTYPE binary_file_format SYSTEM "BinaryFileFormat.dtd">

<binary_file_format name="GIF" default_byte_order="little" default_read_only="false" default_char_set="ascii"
                    web_site="http://www.dcs.ed.ac.uk/home/mxr/gfx/2d/GIF89a.txt" allow_editing="false">
  <struct name="Header" type_name="" comment="">
    <data type="string" name="Signature" format="ascii" len="3" comment="Should be
GIF"/>
    <data type="string" name="Version" format="ascii" len="3" comment="Should be
either 87a or 89a"/>
  </struct>
  <struct name="Logical_Screen_Descriptor" type_name="" comment="">
    <data type="int" format="unsigned" name="Logical Screen Width" len ="2"/>
    <data type="int" format="unsigned" name="Logical Screen Height" len ="2"/>
    <data type="int" format="unsigned" name="Packed_Fields" len ="1" display="bin"
  comment="MSB = Global Color Table Flag(1bit) Color Resolution(3bits) Sort
Flag(1bit) Size of Global Color Table (3bits)"/>
    <data type="int" format="unsigned" name="Background Color Index" len ="1"/>
    <data type="int" format="unsigned" name="Pixel Aspect Ratio" len ="1"/>
  </struct>
  <if test="Logical_Screen_Descriptor.Packed_Fields > 0x7f">
    <for name="Global Color Table" count="1 &lt;&lt;
((Logical_Screen_Descriptor.Packed_Fields &amp; 0x07)+1)" type_name="">
      <struct name="Color" type_name="" comment="">
        <data type="int" format="unsigned" name="Red" len ="1"/>
        <data type="int" format="unsigned" name="Green" len ="1"/>
        <data type="int" format="unsigned" name="Blue" len ="1"/>
      </struct>
    </for>
  </if>


  <for name="Field" stop_test="this.Seperator == 0x3B" type_name=""
  comment="Determine the type of Field">
    <struct name="Field">
      <data type="int" format="unsigned" name="Seperator" display="hex" len ="1"
    comment=""/>
      <if test="Seperator == 0x2c" comment="">
        <struct name="Image_Descriptor" type_name="" comment="Image field">
          <data type="int" format="unsigned" name="Image Left Position" len ="2"/>
          <data type="int" format="unsigned" name="Image Top Position" len ="2"/>
          <data type="int" format="unsigned" name="Image Width" len ="2"/>
          <data type="int" format="unsigned" name="Image Heigth" len ="2"/>
          <data type="int" format="unsigned" name="Packed_Fields" display="bin" len
="1"/>
          <if test="Packed_Fields > 0x7f" comment="">
            <struct name="Local Color Table" type_name="" comment="">
              <for name="Color" count="1 &lt;&lt; ((Packed_Fields &amp; 0x07)+1)"
    type_name="" comment="" >
                <struct name="Color">
                  <data type="int" format="unsigned" name="Red" len ="1"/>
                  <data type="int" format="unsigned" name="Green" len ="1"/>
                  <data type="int" format="unsigned" name="Blue" len ="1"/>
                </struct>
              </for>
            </struct>
          </if>
          <struct name="Table Based Image Data" type_name="" comment="">
            <data type="int" format="unsigned" name="LZW Minimum Code Size" len
="1"/>
            <for name="LZW Data" stop_test="this.blocksize == 0x00" type_name=""
    comment="" >
              <struct name="Data ssubblock" type_name="" comment="">
                <data type="int" format="unsigned" name="blocksize" len="1"/>
                <for count="blocksize">
                  <data type="int" format="unsigned" name="data" display="hex"
      len="1"/>
                </for>
              </struct>
            </for>
          </struct>
        </struct>
      </if>
      <if test="Seperator == 0x21" comment="">
        <struct name="Extension">
          <data type="int" format="unsigned" name="Label" display="hex" len ="1"/>
          <if test="Label == 0xF9" comment="">
            <for name="Graphic Control" stop_test="this.BlockSize == 0x00"
      type_name="" comment="" >
              <struct name="BLOCK" >
                <data type="int" format="unsigned" name="BlockSize" len ="1"/>
                <if test="BlockSize &gt; 0" comment="" >
                  <struct name="DATA" >
                    <data type="int" format="unsigned" name="Packed_Fields" len ="1"/>
                    <data type="int" format="unsigned" name="Delay Time" len ="2"/>
                    <data type="int" format="unsigned" name="Transparent Color Index" len
="1"/>
                  </struct>
                </if>
              </struct>
            </for>
          </if>
          <if test="Label == 0xFE" comment="">
            <for name="Comment string" stop_test="this.BlockSize == 0x00" type_name=""
      comment="" >
              <struct name="Comment string">
                <data type="int" format="unsigned" name="BlockSize" len ="1"/>
                <if test="BlockSize &gt; 0x00" >
                  <data type="string" format="ascii" name="data" len ="BlockSize"/>
                </if>
              </struct>
            </for>
          </if>
          <if test="Label == 0x01" comment="">
            <struct name="Plain text" >
              <data type="int" format="unsigned" name="BlockSize" len ="1"/>
              <data type="int" format="unsigned" name="Text Grid Left Posistion" len
="2"/>
              <data type="int" format="unsigned" name="Text Grid Top Posistion" len
="2"/>
              <data type="int" format="unsigned" name="Text Grid Width" len ="2"/>
              <data type="int" format="unsigned" name="Text Grid Height" len ="2"/>
              <data type="int" format="unsigned" name="Character Cell Width" len
="1"/>
              <data type="int" format="unsigned" name="Character Cell Height" len
="1"/>
              <data type="int" format="unsigned" name="Text Foreground Color Index"
    len ="1"/>
              <data type="int" format="unsigned" name="Text Background Color Index"
    len ="1"/>
              <for name="text" stop_test="this.blocksize == 0x00" type_name=""
    comment="" >
                <struct name="Data subblock" type_name="" comment="">
                  <data type="int" format="unsigned" name="blocksize" len ="1"/>
                  <data type="string" format="ascii" name="data" len ="blocksize"/>
                </struct>
              </for>
            </struct>
          </if>

          <if test="Label == 0xFF">
            <struct name="Application">
              <data type="int" format="unsigned" name="BlockSize" len ="1"
      comment="Should always be 11"/>
              <data type="string" format="ascii" name="Application Identifier" len
="8"/>
              <data type="string" format="ascii" name="Application Authentication
Code" len ="3"/>
              <for name="Data" stop_test="this.blocksize == 0x00" type_name=""
      comment="" >
                <struct name="Application Data" type_name="" comment="">
                  <data type="int" format="unsigned" name="blocksize" len ="1"/>
                  <data type="none" display="hex" name="data" len ="blocksize"/>
                </struct>
              </for>
            </struct>
          </if>

        </struct>
      </if>
    </struct>
  </for>
</binary_file_format>