positron/doc/sai.html

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   4   <title>Positron Developer's Guide: SAI File Format</title>
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   7 <h1>Positron Developer's Guide: SAI File Format</h1>
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   9 <p>
  10 This document explains the format of the SAI files.  SAI files are
  11 used in the database as a table of contents.  Every non-deleted record
  12 in the database will have a record in the SAI file.  SAI records are
  13 all the same size, so it is very easy to modify the contents of this
  14 file in place, including removing and reordering entries.
  15 </p>
  16
  17 <p>
  18 A record in a SAI file consists of a pointer to a MDB record, and to
  19 its associated PAI module (if applicable).  The pointer to the PAI
  20 module does not point to the start of the module, however, but to the
  21 location of the <em id="caveat">first entry within the module</em>.  See the
  22 <a href="pai.html">PAI file format</a> for more information.
  23 </p>
  24
  25 <table class="fielddef">
  26 <tr><th>Word Offset</th><th>Size (words)</th><th>Description</th></tr>
  27 <tr><td>0</td><td>2</td><td>Signature, "0x05181971"</td></tr>
  28 <tr><td>2</td><td>2</td><td>Reserved (zero by default)</td></tr>
  29 <tr><td>4</td><td>1</td><td>Number of entries (N)</td></tr>
  30 <tr><td>5</td><td>3</td><td>Reserved (zero by default) </td></tr>
  31 <tr><td>8</td><td>4</td><td>0x00000000, 0x00000000 (looks like an empty record)</td></tr>
  32 <tr><td>12</td><td>2</td><td>MDB pointer for record 1</td></tr>
  33 <tr><td>14</td><td>2</td><td>PAI pointer for record 1</td></tr>
  34 <tr><td>...</td><td>...</td><td>...</td></tr>
  35 <tr><td>12+4*(i-1)</td><td>2</td><td>MDB pointer for record i</td></tr>
  36 <tr><td>14+4*(i-1)</td><td>2</td><td>PAI pointer for record i</td></tr>
  37 <tr><td>...</td><td>...</td><td>...</td></tr>
  38 <tr><td>12+4*(N-1)</td><td>2</td><td>MDB pointer for record N</td></tr>
  39 <tr><td>14+4*(N-1)</td><td>2</td><td>PAI pointer for record N</td></tr>
  40 <tr><td>12+4*N</td><td>4</td><td>0x00000000, 0x00000000 (looks like an empty record)</td></tr>
  41 </table>
  42
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