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Graham Nelson edf47b5c10 Fixed Booklet Title infelicity
2020-04-08 23:41:00 +01:00

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Binary Files</title>
<meta name="viewport" content="width=device-width initial-scale=1">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Language" content="en-gb">
<link href="../inweb.css" rel="stylesheet" rev="stylesheet" type="text/css">
</head>
<body>
<nav role="navigation">
<h1><a href="../webs.html">Sources</a></h1>
<ul>
<li><a href="../inweb/index.html">inweb</a></li>
</ul>
<h2>Foundation</h2>
<ul>
<li><a href="../foundation-module/index.html">foundation-module</a></li>
<li><a href="../foundation-test/index.html">foundation-test</a></li>
</ul>
</nav>
<main role="main">
<!--Weave of 'Binary Files' generated by 7-->
<ul class="crumbs"><li><a href="../webs.html">Source</a></li><li><a href="index.html">foundation</a></li><li><a href="index.html#6">Chapter 6: Media</a></li><li><b>Binary Files</b></li></ul><p class="purpose">Routines for reading raw data from binary files.</p>
<ul class="toc"><li><a href="#SP1">&#167;1. Reading binary data</a></li><li><a href="#SP7">&#167;7. Size</a></li><li><a href="#SP8">&#167;8. Opening</a></li><li><a href="#SP9">&#167;9. Copying</a></li></ul><hr class="tocbar">
<p class="inwebparagraph"><a id="SP1"></a><b>&#167;1. Reading binary data. </b>To begin with, integers of 8, 16, 32 and 64 bit widths respectively,
arranged with most significant byte (MSB) first.
</p>
<pre class="display">
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::read_int8</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">result</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c1</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">c1</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="plain">*</span><span class="identifier">result</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">c1</span><span class="plain">;</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::read_int16</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">result</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c1</span><span class="plain">, </span><span class="identifier">c2</span><span class="plain">;</span>
<span class="identifier">c1</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c2</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">c1</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c2</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="plain">*</span><span class="identifier">result</span><span class="plain"> = (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">c1</span><span class="plain">) &lt;&lt; </span><span class="constant">8</span><span class="plain">) + ((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">c2</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::read_int32</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">result</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c1</span><span class="plain">, </span><span class="identifier">c2</span><span class="plain">, </span><span class="identifier">c3</span><span class="plain">, </span><span class="identifier">c4</span><span class="plain">;</span>
<span class="identifier">c1</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c2</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c3</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c4</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">c1</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c2</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c3</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c4</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="plain">*</span><span class="identifier">result</span><span class="plain"> = (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">c1</span><span class="plain">) &lt;&lt; </span><span class="constant">24</span><span class="plain">) +</span>
<span class="plain">(((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">c2</span><span class="plain">) &lt;&lt; </span><span class="constant">16</span><span class="plain">) +</span>
<span class="plain">(((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">c3</span><span class="plain">) &lt;&lt; </span><span class="constant">8</span><span class="plain">) + ((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">c4</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::read_int64</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> *</span><span class="identifier">result</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c1</span><span class="plain">, </span><span class="identifier">c2</span><span class="plain">, </span><span class="identifier">c3</span><span class="plain">, </span><span class="identifier">c4</span><span class="plain">, </span><span class="identifier">c5</span><span class="plain">, </span><span class="identifier">c6</span><span class="plain">, </span><span class="identifier">c7</span><span class="plain">, </span><span class="identifier">c8</span><span class="plain">;</span>
<span class="identifier">c1</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c2</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c3</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c4</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c5</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c6</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c7</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c8</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">c1</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c2</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c3</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c4</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c5</span><span class="plain"> == </span><span class="identifier">EOF</span>
<span class="plain">|| </span><span class="identifier">c6</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c7</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c8</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="plain">*</span><span class="identifier">result</span><span class="plain"> = (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c1</span><span class="plain">) &lt;&lt; </span><span class="constant">56</span><span class="plain">) +</span>
<span class="plain"> (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c2</span><span class="plain">) &lt;&lt; </span><span class="constant">48</span><span class="plain">) +</span>
<span class="plain"> (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c3</span><span class="plain">) &lt;&lt; </span><span class="constant">40</span><span class="plain">) +</span>
<span class="plain"> (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c4</span><span class="plain">) &lt;&lt; </span><span class="constant">32</span><span class="plain">) +</span>
<span class="plain"> (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c5</span><span class="plain">) &lt;&lt; </span><span class="constant">24</span><span class="plain">) +</span>
<span class="plain"> (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c6</span><span class="plain">) &lt;&lt; </span><span class="constant">16</span><span class="plain">) +</span>
<span class="plain"> (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c7</span><span class="plain">) &lt;&lt; </span><span class="constant">8</span><span class="plain">) +</span>
<span class="plain">((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain">) </span><span class="identifier">c8</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::read_int8 is used in 6/sd (<a href="6-sd.html#SP2">&#167;2</a>, <a href="6-sd.html#SP3">&#167;3</a>).</p>
<p class="endnote">The function BinaryFiles::read_int16 is used in 6/id (<a href="6-id.html#SP1">&#167;1</a>), 6/sd (<a href="6-sd.html#SP1">&#167;1</a>, <a href="6-sd.html#SP2">&#167;2</a>, <a href="6-sd.html#SP3">&#167;3</a>).</p>
<p class="endnote">The function BinaryFiles::read_int32 is used in <a href="#SP5">&#167;5</a>, 6/id (<a href="6-id.html#SP2">&#167;2</a>), 6/sd (<a href="6-sd.html#SP1">&#167;1</a>, <a href="6-sd.html#SP2">&#167;2</a>, <a href="6-sd.html#SP3">&#167;3</a>).</p>
<p class="endnote">The function BinaryFiles::read_int64 is used in 6/sd (<a href="6-sd.html#SP2">&#167;2</a>).</p>
<p class="inwebparagraph"><a id="SP2"></a><b>&#167;2. </b></p>
<pre class="display">
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::write_int32</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">val</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c1</span><span class="plain"> = (</span><span class="reserved">int</span><span class="plain">) ((</span><span class="identifier">val</span><span class="plain"> &gt;&gt; </span><span class="constant">24</span><span class="plain">) &amp; </span><span class="constant">0xFF</span><span class="plain">);</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c2</span><span class="plain"> = (</span><span class="reserved">int</span><span class="plain">) ((</span><span class="identifier">val</span><span class="plain"> &gt;&gt; </span><span class="constant">16</span><span class="plain">) &amp; </span><span class="constant">0xFF</span><span class="plain">);</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c3</span><span class="plain"> = (</span><span class="reserved">int</span><span class="plain">) ((</span><span class="identifier">val</span><span class="plain"> &gt;&gt; </span><span class="constant">8</span><span class="plain">) &amp; </span><span class="constant">0xFF</span><span class="plain">);</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c4</span><span class="plain"> = (</span><span class="reserved">int</span><span class="plain">) (</span><span class="identifier">val</span><span class="plain"> &amp; </span><span class="constant">0xFF</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">putc</span><span class="plain">(</span><span class="identifier">c1</span><span class="plain">, </span><span class="identifier">binary_file</span><span class="plain">) == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">putc</span><span class="plain">(</span><span class="identifier">c2</span><span class="plain">, </span><span class="identifier">binary_file</span><span class="plain">) == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">putc</span><span class="plain">(</span><span class="identifier">c3</span><span class="plain">, </span><span class="identifier">binary_file</span><span class="plain">) == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">putc</span><span class="plain">(</span><span class="identifier">c4</span><span class="plain">, </span><span class="identifier">binary_file</span><span class="plain">) == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::write_int32 appears nowhere else.</p>
<p class="inwebparagraph"><a id="SP3"></a><b>&#167;3. </b>We will sometimes need to toggle between MSB and LSB representation of
integers 32 or 64 bits wide:
</p>
<pre class="display">
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">BinaryFiles::swap_bytes32</span><span class="plain">(</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">value</span><span class="plain">) {</span>
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">result</span><span class="plain"> = (((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff</span><span class="plain">) &lt;&lt; </span><span class="constant">24</span><span class="plain">) +</span>
<span class="plain">((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff00</span><span class="plain">) &lt;&lt; </span><span class="constant">8</span><span class="plain">) +</span>
<span class="plain">((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff0000</span><span class="plain">) &gt;&gt; </span><span class="constant">8</span><span class="plain">) +</span>
<span class="plain">((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff000000</span><span class="plain">) &gt;&gt; </span><span class="constant">24</span><span class="plain"> ) );</span>
<span class="plain">*</span><span class="identifier">value</span><span class="plain"> = </span><span class="identifier">result</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">BinaryFiles::swap_bytes64</span><span class="plain">(</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> *</span><span class="identifier">value</span><span class="plain">) {</span>
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="reserved">long</span><span class="plain"> </span><span class="identifier">result</span><span class="plain"> = (((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff</span><span class="plain">) &lt;&lt; </span><span class="constant">56</span><span class="plain">) +</span>
<span class="plain"> ((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff00</span><span class="plain">) &lt;&lt; </span><span class="constant">40</span><span class="plain">) +</span>
<span class="plain"> ((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff0000</span><span class="plain">) &lt;&lt; </span><span class="constant">24</span><span class="plain">) +</span>
<span class="plain"> ((*</span><span class="identifier">value</span><span class="plain"> &amp; </span><span class="constant">0xff000000</span><span class="plain">) &lt;&lt; </span><span class="constant">8</span><span class="plain">) +</span>
<span class="plain"> ((*</span><span class="identifier">value</span><span class="plain"> &gt;&gt; </span><span class="constant">8</span><span class="plain">) &amp; </span><span class="constant">0xff000000</span><span class="plain">) +</span>
<span class="plain"> ((*</span><span class="identifier">value</span><span class="plain"> &gt;&gt; </span><span class="constant">24</span><span class="plain">) &amp; </span><span class="constant">0xff0000</span><span class="plain">) +</span>
<span class="plain"> ((*</span><span class="identifier">value</span><span class="plain"> &gt;&gt; </span><span class="constant">40</span><span class="plain">) &amp; </span><span class="constant">0xff00</span><span class="plain">) +</span>
<span class="plain"> ((*</span><span class="identifier">value</span><span class="plain"> &gt;&gt; </span><span class="constant">56</span><span class="plain">) &amp; </span><span class="constant">0xff</span><span class="plain">) );</span>
<span class="plain">*</span><span class="identifier">value</span><span class="plain"> = </span><span class="identifier">result</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::swap_bytes32 is used in 6/sd (<a href="6-sd.html#SP2">&#167;2</a>).</p>
<p class="endnote">The function BinaryFiles::swap_bytes64 is used in 6/sd (<a href="6-sd.html#SP2">&#167;2</a>).</p>
<p class="inwebparagraph"><a id="SP4"></a><b>&#167;4. </b>Some file formats also have variable-sized integers, as a sequence of
bytes (most significant first) in which each byte consists of seven bits
of data plus a most significant bit which marks that a continuation byte
follows:
</p>
<pre class="display">
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::read_variable_length_integer</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">result</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c</span><span class="plain">;</span>
<span class="plain">*</span><span class="identifier">result</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
<span class="reserved">do</span><span class="plain"> {</span>
<span class="identifier">c</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">c</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="plain">*</span><span class="identifier">result</span><span class="plain"> = (*</span><span class="identifier">result</span><span class="plain"> &lt;&lt; </span><span class="constant">7</span><span class="plain">) + (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">char</span><span class="plain">) </span><span class="identifier">c</span><span class="plain">) &amp; </span><span class="constant">0x7F</span><span class="plain">);</span>
<span class="plain">} </span><span class="reserved">while</span><span class="plain"> (((</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">char</span><span class="plain">) </span><span class="identifier">c</span><span class="plain">) &amp; </span><span class="constant">0x80</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::read_variable_length_integer is used in 6/sd (<a href="6-sd.html#SP3">&#167;3</a>).</p>
<p class="inwebparagraph"><a id="SP5"></a><b>&#167;5. </b>Here we read just the mantissa of a particular representation of
floating-point numbers:
</p>
<pre class="display">
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::read_float80</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> *</span><span class="identifier">result</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c1</span><span class="plain">, </span><span class="identifier">c2</span><span class="plain">, </span><span class="identifier">exp</span><span class="plain">;</span>
<span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">prev</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">, </span><span class="identifier">mantissa</span><span class="plain">;</span>
<span class="identifier">c1</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="identifier">c2</span><span class="plain"> = </span><span class="identifier">getc</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">c1</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain"> || </span><span class="identifier">c2</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="reserved">if</span><span class="plain"> (!</span><span class="functiontext">BinaryFiles::read_int32</span><span class="plain">(</span><span class="identifier">binary_file</span><span class="plain">, &amp;</span><span class="identifier">mantissa</span><span class="plain">)) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="identifier">exp</span><span class="plain"> = </span><span class="constant">30</span><span class="plain"> - </span><span class="identifier">c2</span><span class="plain">;</span>
<span class="reserved">while</span><span class="plain"> (</span><span class="identifier">exp</span><span class="plain">--) {</span>
<span class="identifier">prev</span><span class="plain"> = </span><span class="identifier">mantissa</span><span class="plain">;</span>
<span class="identifier">mantissa</span><span class="plain"> &gt;&gt;= </span><span class="constant">1</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">prev</span><span class="plain"> &amp; </span><span class="constant">1</span><span class="plain">) </span><span class="identifier">mantissa</span><span class="plain">++;</span>
<span class="plain">*</span><span class="identifier">result</span><span class="plain"> = (</span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain">) </span><span class="identifier">mantissa</span><span class="plain">;</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::read_float80 is used in 6/sd (<a href="6-sd.html#SP1">&#167;1</a>).</p>
<p class="inwebparagraph"><a id="SP6"></a><b>&#167;6. </b>And lastly we read a string of a supplied length from the file, and
then null terminate it to make it valid C string. (<code class="display"><span class="extract">string</span></code> must therefore
be at least <code class="display"><span class="extract">length</span></code> plus 1 bytes long.)
</p>
<pre class="display">
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::read_string</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">binary_file</span><span class="plain">, </span><span class="reserved">char</span><span class="plain"> *</span><span class="identifier">string</span><span class="plain">, </span><span class="reserved">unsigned</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">length</span><span class="plain">) {</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">length</span><span class="plain"> &gt; </span><span class="constant">0</span><span class="plain">) {</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fread</span><span class="plain">(</span><span class="identifier">string</span><span class="plain">, </span><span class="constant">1</span><span class="plain">, </span><span class="identifier">length</span><span class="plain">, </span><span class="identifier">binary_file</span><span class="plain">) != </span><span class="identifier">length</span><span class="plain">) </span><span class="reserved">return</span><span class="plain"> </span><span class="constant">FALSE</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="identifier">string</span><span class="plain">[</span><span class="identifier">length</span><span class="plain">] = </span><span class="constant">0</span><span class="plain">;</span>
<span class="reserved">return</span><span class="plain"> </span><span class="constant">TRUE</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::read_string is used in 6/sd (<a href="6-sd.html#SP3">&#167;3</a>).</p>
<p class="inwebparagraph"><a id="SP7"></a><b>&#167;7. Size. </b></p>
<pre class="display">
<span class="reserved">long</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::size</span><span class="plain">(</span><span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">F</span><span class="plain">) {</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">TEST_FILE</span><span class="plain"> = </span><span class="functiontext">BinaryFiles::try_to_open_for_reading</span><span class="plain">(</span><span class="identifier">F</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">TEST_FILE</span><span class="plain">) {</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">fseek</span><span class="plain">(</span><span class="identifier">TEST_FILE</span><span class="plain">, </span><span class="constant">0</span><span class="plain">, </span><span class="identifier">SEEK_END</span><span class="plain">) == </span><span class="constant">0</span><span class="plain">) {</span>
<span class="reserved">long</span><span class="plain"> </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">file_size</span><span class="plain"> = </span><span class="identifier">ftell</span><span class="plain">(</span><span class="identifier">TEST_FILE</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">file_size</span><span class="plain"> == -1</span><span class="identifier">L</span><span class="plain">) </span><span class="functiontext">Errors::fatal_with_file</span><span class="plain">(</span><span class="string">"ftell failed on linked file"</span><span class="plain">, </span><span class="identifier">F</span><span class="plain">);</span>
<span class="functiontext">BinaryFiles::close</span><span class="plain">(</span><span class="identifier">TEST_FILE</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">file_size</span><span class="plain">;</span>
<span class="plain">} </span><span class="reserved">else</span><span class="plain"> </span><span class="functiontext">Errors::fatal_with_file</span><span class="plain">(</span><span class="string">"fseek failed on linked file"</span><span class="plain">, </span><span class="identifier">F</span><span class="plain">);</span>
<span class="functiontext">BinaryFiles::close</span><span class="plain">(</span><span class="identifier">TEST_FILE</span><span class="plain">);</span>
<span class="plain">}</span>
<span class="reserved">return</span><span class="plain"> -1</span><span class="identifier">L</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::size appears nowhere else.</p>
<p class="inwebparagraph"><a id="SP8"></a><b>&#167;8. Opening. </b></p>
<pre class="display">
<span class="reserved">FILE</span><span class="plain"> *</span><span class="functiontext">BinaryFiles::open_for_reading</span><span class="plain">(</span><span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">F</span><span class="plain">) {</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">handle</span><span class="plain"> = </span><span class="functiontext">Filenames::fopen</span><span class="plain">(</span><span class="identifier">F</span><span class="plain">, </span><span class="string">"rb"</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">handle</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="functiontext">Errors::fatal_with_file</span><span class="plain">(</span><span class="string">"unable to read file"</span><span class="plain">, </span><span class="identifier">F</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">handle</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="functiontext">BinaryFiles::try_to_open_for_reading</span><span class="plain">(</span><span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">F</span><span class="plain">) {</span>
<span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Filenames::fopen</span><span class="plain">(</span><span class="identifier">F</span><span class="plain">, </span><span class="string">"rb"</span><span class="plain">);</span>
<span class="plain">}</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="functiontext">BinaryFiles::open_for_writing</span><span class="plain">(</span><span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">F</span><span class="plain">) {</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">handle</span><span class="plain"> = </span><span class="functiontext">Filenames::fopen</span><span class="plain">(</span><span class="identifier">F</span><span class="plain">, </span><span class="string">"wb"</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">handle</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) </span><span class="functiontext">Errors::fatal_with_file</span><span class="plain">(</span><span class="string">"unable to write file"</span><span class="plain">, </span><span class="identifier">F</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">handle</span><span class="plain">;</span>
<span class="plain">}</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="functiontext">BinaryFiles::try_to_open_for_writing</span><span class="plain">(</span><span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">F</span><span class="plain">) {</span>
<span class="reserved">return</span><span class="plain"> </span><span class="functiontext">Filenames::fopen</span><span class="plain">(</span><span class="identifier">F</span><span class="plain">, </span><span class="string">"wb"</span><span class="plain">);</span>
<span class="plain">}</span>
<span class="reserved">void</span><span class="plain"> </span><span class="functiontext">BinaryFiles::close</span><span class="plain">(</span><span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">handle</span><span class="plain">) {</span>
<span class="identifier">fclose</span><span class="plain">(</span><span class="identifier">handle</span><span class="plain">);</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::open_for_reading appears nowhere else.</p>
<p class="endnote">The function BinaryFiles::try_to_open_for_reading is used in <a href="#SP7">&#167;7</a>, <a href="#SP9">&#167;9</a>.</p>
<p class="endnote">The function BinaryFiles::open_for_writing appears nowhere else.</p>
<p class="endnote">The function BinaryFiles::try_to_open_for_writing is used in <a href="#SP9">&#167;9</a>.</p>
<p class="endnote">The function BinaryFiles::close is used in <a href="#SP7">&#167;7</a>, <a href="#SP9">&#167;9</a>.</p>
<p class="inwebparagraph"><a id="SP9"></a><b>&#167;9. Copying. </b>This achieves a binary copy of a file when we haven't got access to the shell,
or to system APIs.
</p>
<pre class="display">
<span class="reserved">int</span><span class="plain"> </span><span class="functiontext">BinaryFiles::copy</span><span class="plain">(</span><span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">from</span><span class="plain">, </span><span class="reserved">filename</span><span class="plain"> *</span><span class="identifier">to</span><span class="plain">, </span><span class="reserved">int</span><span class="plain"> </span><span class="identifier">suppress_error</span><span class="plain">) {</span>
<span class="reserved">if</span><span class="plain"> ((</span><span class="identifier">from</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) || (</span><span class="identifier">to</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">))</span>
<span class="functiontext">Errors::fatal</span><span class="plain">(</span><span class="string">"files confused in copier"</span><span class="plain">);</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">FROM</span><span class="plain"> = </span><span class="functiontext">BinaryFiles::try_to_open_for_reading</span><span class="plain">(</span><span class="identifier">from</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">FROM</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) {</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">suppress_error</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">) </span><span class="functiontext">Errors::fatal_with_file</span><span class="plain">(</span><span class="string">"unable to read file"</span><span class="plain">, </span><span class="identifier">from</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> -1;</span>
<span class="plain">}</span>
<span class="reserved">FILE</span><span class="plain"> *</span><span class="identifier">TO</span><span class="plain"> = </span><span class="functiontext">BinaryFiles::try_to_open_for_writing</span><span class="plain">(</span><span class="identifier">to</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">TO</span><span class="plain"> == </span><span class="identifier">NULL</span><span class="plain">) {</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">suppress_error</span><span class="plain"> == </span><span class="constant">FALSE</span><span class="plain">) </span><span class="functiontext">Errors::fatal_with_file</span><span class="plain">(</span><span class="string">"unable to write to file"</span><span class="plain">, </span><span class="identifier">to</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> -1;</span>
<span class="plain">}</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">size</span><span class="plain"> = </span><span class="constant">0</span><span class="plain">;</span>
<span class="reserved">while</span><span class="plain"> (</span><span class="constant">TRUE</span><span class="plain">) {</span>
<span class="reserved">int</span><span class="plain"> </span><span class="identifier">c</span><span class="plain"> = </span><span class="identifier">fgetc</span><span class="plain">(</span><span class="identifier">FROM</span><span class="plain">);</span>
<span class="reserved">if</span><span class="plain"> (</span><span class="identifier">c</span><span class="plain"> == </span><span class="identifier">EOF</span><span class="plain">) </span><span class="reserved">break</span><span class="plain">;</span>
<span class="identifier">size</span><span class="plain">++;</span>
<span class="identifier">putc</span><span class="plain">(</span><span class="identifier">c</span><span class="plain">, </span><span class="identifier">TO</span><span class="plain">);</span>
<span class="plain">}</span>
<span class="functiontext">BinaryFiles::close</span><span class="plain">(</span><span class="identifier">FROM</span><span class="plain">); </span><span class="functiontext">BinaryFiles::close</span><span class="plain">(</span><span class="identifier">TO</span><span class="plain">);</span>
<span class="reserved">return</span><span class="plain"> </span><span class="identifier">size</span><span class="plain">;</span>
<span class="plain">}</span>
</pre>
<p class="inwebparagraph"></p>
<p class="endnote">The function BinaryFiles::copy appears nowhere else.</p>
<hr class="tocbar">
<ul class="toc"><li><i>(This section begins Chapter 6: Media.)</i></li><li><a href="6-id.html">Continue with 'Image Dimensions'</a></li></ul><hr class="tocbar">
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