path: root/doc/GlueGen_Mapping.html

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<nav id="TOC" role="doc-toc">
    <strong>Contents</strong><label for="contents">⊕</label>
  <input type="checkbox" id="contents">
  <ul>
  <li><a href="#gluegen-native-data--function-mapping-for-java">GlueGen
  Native Data &amp; Function Mapping for Java™</a>
  <ul>
  <li><a href="#references">References</a></li>
  <li><a href="#overview">Overview</a></li>
  <li><a href="#primitive-mapping">Primitive Mapping</a>
  <ul>
  <li><a href="#string-mapping">String Mapping</a></li>
  <li><a href="#alignment-for-compound-data">Alignment for Compound
  Data</a></li>
  </ul></li>
  <li><a href="#struct-mapping">Struct Mapping</a>
  <ul>
  <li><a href="#gluegen-struct-settings">GlueGen Struct
  Settings</a></li>
  <li><a href="#struct-mapping-notes">Struct Mapping Notes</a></li>
  <li><a href="#struct-java-signature-table">Struct Java Signature
  Table</a></li>
  <li><a href="#struct-setter-pseudo-code">Struct Setter
  Pseudo-Code</a></li>
  </ul></li>
  <li><a href="#platform-header-files">Platform Header Files</a></li>
  <li><a href="#pre-defined-macros">Pre-Defined Macros</a></li>
  </ul></li>
  </ul>
</nav>

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<h1 id="gluegen-native-data--function-mapping-for-java">GlueGen Native
Data &amp; Function Mapping for Java™</h1>
<h2 id="references">References</h2>
<ul>
<li><a href="https://jogamp.org/cgit/gluegen.git/about/">GlueGen Git
Repo</a></li>
<li><a
href="https://jogamp.org/deployment/jogamp-next/javadoc/gluegen/javadoc/">GlueGen
Java™ API-Doc</a></li>
<li><a href="https://jogamp.org/gluegen/doc/manual/">GlueGen
Manual</a></li>
<li><a href="https://jogamp.org/gluegen/www/">GlueGen Project
Page</a></li>
<li><a href="https://jogamp.org/gluegen/doc/HowToBuild.html">How To
Build</a></li>
</ul>
<h2 id="overview">Overview</h2>
<p><a href="https://jogamp.org/gluegen/www/">GlueGen</a> is a compiler
for function and data-structure declarations, generating Java and JNI C
code offline at compile time and allows using native libraries within
your Java application.</p>
<p>It reads ANSI C header files and separate configuration files which
provide control over many aspects of the glue code generation. GlueGen
uses a complete ANSI C parser and an internal representation (IR)
capable of representing all C types to represent the APIs for which it
generates interfaces. It has the ability to perform significant
transformations on the IR before glue code emission.</p>
<p>GlueGen can produce native foreign function bindings to Java as well
as map native data structures to be fully accessible from Java including
potential calls to embedded function pointer.</p>
<p>GlueGen is also capable to bind even low-level APIs such as the Java
Native Interface (JNI) and the AWT Native Interface (JAWT) back up to
the Java programming language.</p>
<p>GlueGen utilizes <a
href="https://jogamp.org/cgit/jcpp.git/about/">JCPP</a>, migrated C
preprocessor written in Java.</p>
<p>GlueGen is used for the <a href="https://jogamp.org">JogAmp</a>
projects <a href="https://jogamp.org/cgit/joal.git/about/">JOAL</a>, <a
href="https://jogamp.org/cgit/jogl.git/about/">JOGL</a> and <a
href="https://jogamp.org/cgit/jocl.git/">JOCL</a>.</p>
<p>GlueGen is part of <a href="https://jogamp.org">the JogAmp
project</a>.</p>
<h2 id="primitive-mapping">Primitive Mapping</h2>
<p>Gluegen has build-in types (terminal symbols) for:</p>
<table>
<thead>
<tr class="header">
<th style="text-align: left;">type</th>
<th style="text-align: left;">java-bits</th>
<th style="text-align: left;">native-bits <br> x32</th>
<th style="text-align: left;">native bits <br> x64</th>
<th style="text-align: left;">type</th>
<th style="text-align: left;">signed</th>
<th style="text-align: left;">origin</th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td style="text-align: left;">void</td>
<td style="text-align: left;">0</td>
<td style="text-align: left;">0</td>
<td style="text-align: left;">0</td>
<td style="text-align: left;">void</td>
<td style="text-align: left;">void</td>
<td style="text-align: left;">ANSI-C</td>
</tr>
<tr class="even">
<td style="text-align: left;">char</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">any</td>
<td style="text-align: left;">ANSI-C</td>
</tr>
<tr class="odd">
<td style="text-align: left;">short</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">any</td>
<td style="text-align: left;">ANSI-C</td>
</tr>
<tr class="even">
<td style="text-align: left;">int</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">any</td>
<td style="text-align: left;">ANSI-C</td>
</tr>
<tr class="odd">
<td style="text-align: left;">long</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;"><strong>32</strong>†</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">any</td>
<td style="text-align: left;">ANSI-C - Windows</td>
</tr>
<tr class="even">
<td style="text-align: left;">long</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;"><strong>64</strong></td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">any</td>
<td style="text-align: left;">ANSI-C - Unix</td>
</tr>
<tr class="odd">
<td style="text-align: left;">float</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">float</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">ANSI-C</td>
</tr>
<tr class="even">
<td style="text-align: left;">double</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">double</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">ANSI-C</td>
</tr>
<tr class="odd">
<td style="text-align: left;">__int32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">any</td>
<td style="text-align: left;">windows</td>
</tr>
<tr class="even">
<td style="text-align: left;">__int64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">any</td>
<td style="text-align: left;">windows</td>
</tr>
<tr class="odd">
<td style="text-align: left;">int8_t</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="even">
<td style="text-align: left;">uint8_t</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">unsigned</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="odd">
<td style="text-align: left;">int16_t</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="even">
<td style="text-align: left;">uint16_t</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">unsigned</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="odd">
<td style="text-align: left;">int32_t</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="even">
<td style="text-align: left;">uint32_t</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">unsigned</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="odd">
<td style="text-align: left;">int64_t</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="even">
<td style="text-align: left;">uint64_t</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">unsigned</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="odd">
<td style="text-align: left;">intptr_t</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="even">
<td style="text-align: left;">uintptr_t</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">unsigned</td>
<td style="text-align: left;">stdint.h</td>
</tr>
<tr class="odd">
<td style="text-align: left;">ptrdiff_t</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">stddef.h</td>
</tr>
<tr class="even">
<td style="text-align: left;">size_t</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">64</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">unsigned</td>
<td style="text-align: left;">stddef.h</td>
</tr>
<tr class="odd">
<td style="text-align: left;">wchar_t</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">32</td>
<td style="text-align: left;">integer</td>
<td style="text-align: left;">signed</td>
<td style="text-align: left;">stddef.h</td>
</tr>
</tbody>
</table>
<p><strong>Warning:</strong> Try to avoid unspecified bit sized types,
especially <strong>long</strong>, since it differs on Unix and
Windows!<br />
<strong>Notes:</strong></p>
<ul>
<li>† Type <strong>long</strong> will result in broken code on Windows,
since we don't differentiate the OS and it's bit size is ambiguous.</li>
<li>Anonymous void-pointer <em>void*</em> are mapped to NIO
<em>Buffer</em>.</li>
<li>Pointers to pointer-size types like <em>intptr_t*</em>,
<em>uintptr_t*</em>, <em>ptrdiff_t*</em> and <em>size_t*</em> are mapped
to <em>PointerBuffer</em>, to reflect the architecture depending storage
size.</li>
</ul>
<h3 id="string-mapping">String Mapping</h3>
<h4 id="function-return-string-values">Function return String
values</h4>
<p>Function return values are currently mapped from <code>char*</code>
to Java String using <em>UTF-8</em> via JNI function</p>
<blockquote>
<p><code>jstring NewStringUTF(JNIEnv *env, const char *bytes)</code></p>
</blockquote>
<p><em>FIXME</em>: This might need more flexibility in case UTF-8 is not
suitable for 8-bit wide <code>char</code> mappings or wide characters,
e.g. for UTF-16 needs to be supported.</p>
<h4 id="function-argument-string-values">Function argument String
values</h4>
<p>Function argument values are either mapped from <code>char*</code> to
Java String using <em>UTF-8</em> via JNI function</p>
<blockquote>
<p><code>const char * GetStringUTFChars(JNIEnv *env, jstring string, jboolean *isCopy)</code>.</p>
</blockquote>
<p>Alternatively, if a 16-bit wide <em>character</em> type has been
detected, i.e. <em>short</em>, the native <em>character</em> are mapped
to Java using <em>UTF-16</em> via JNI function</p>
<blockquote>
<p><code>void GetStringRegion(JNIEnv *env, jstring str, jsize start, jsize len, jchar *buf)</code>.</p>
</blockquote>
<h4 id="struct-string-mapping">Struct String mapping</h4>
<p>String value mapping for <code>Struct</code> fields is performed
solely from the Java side using <em>Charset</em> and is hence most
flexible.</p>
<p>By default, <em>UTF-8</em> is being used for getter and setter of
String values.<br />
The <em>Struct</em> class provides two methods to get and set the used
<em>Charset</em> for conversion</p>
<pre><code>  /** Returns the Charset for this class&#39;s String mapping, default is StandardCharsets.UTF_8. */
  public static Charset getCharset() { return _charset; };

  /** Sets the Charset for this class&#39;s String mapping, default is StandardCharsets.UTF_8. */
  public static void setCharset(Charset cs) { _charset = cs; }
</code></pre>
<p>In case the String length has not been configured via
<code>ReturnedArrayLength</code>, it will be dynamically calculated via
<code>strnlen(aptr, max_len)</code>.<br />
The maximum length default for the <code>strnlen(..)</code> operation is
8192 bytes and can be get and set using:</p>
<pre><code>  /** Returns the maximum number of bytes to read to determine native string length using `strnlen(..)`, default is 8192. */
  public static int getMaxStrnlen() { return _max_strnlen; };

  /** Sets the maximum number of bytes to read to determine native string length using `strnlen(..)`, default is 8192. */
  public static void setMaxStrnlen(int v) { _max_strnlen = v; }</code></pre>
<p><em>FIXME</em>: This only works reliable using an 8-bit Charset
encoding, e.g. the default <em>UTF-8</em>.</p>
<h3 id="alignment-for-compound-data">Alignment for Compound Data</h3>
<p>In general, depending on CPU and it's configuration (OS), alignment
is set up for each type (char, short, int, long, ..).</p>
<p>Compounds (structures) are aligned naturally, i.e. their inner
components are aligned<br />
and are itself aligned to it's largest element.</p>
<p>See:</p>
<ul>
<li><a
href="http://en.wikipedia.org/wiki/Data_structure_alignment">Wikipedia
Data Structure Alignment</a></li>
<li><a
href="http://en.wikipedia.org/wiki/Data_structure_alignment#Data_structure_padding">Wikipedia
Data Structure Alignment - Padding</a></li>
<li><a href="http://www.viva64.com/en/l/0021/">Viva64 Data
Alignment</a></li>
<li><a
href="http://developer.apple.com/library/mac/#documentation/Darwin/Conceptual/64bitPorting/transition/transition.html#//apple_ref/doc/uid/TP40001064-CH207-SW1">Apple:
Darwin 64bit Porting - Data Type Size &amp; Alignment</a></li>
</ul>
<h4 id="simple-alignment-arithmetic">Simple alignment arithmetic</h4>
<p>Modulo operation, where the 2nd handles the case offset ==
alignment:</p>
<blockquote>
<p>padding = ( alignment - ( offset % alignment ) ) % alignment ;<br />
aligned_offset = offset + padding ;</p>
</blockquote>
<p>Optimization utilizing alignment as a multiple of 2
<code>-&gt; x % 2n == x &amp; ( 2n - 1 )</code></p>
<blockquote>
<p>remainder = offset &amp; ( alignment - 1 ) ;<br />
padding = ( remainder &gt; 0 ) ? alignment - remainder : 0 ;<br />
aligned_offset = offset + padding ;</p>
</blockquote>
<p>Without branching, using the 2nd modulo operation for the case offset
== alignment:</p>
<blockquote>
<p>padding = ( alignment - ( offset &amp; ( alignment - 1 ) ) ) &amp; (
alignment - 1 ) ;<br />
aligned_offset = offset + padding ;</p>
</blockquote>
<p>See
<code>com.jogamp.gluegen.cgram.types.SizeThunk.align(..)</code>.</p>
<h4
id="type-size--alignment-for-x86-x86_64-armv6l-32bit-eabi-and-windowmingwmingw64">Type
Size &amp; Alignment for x86, x86_64, armv6l-32bit-eabi and
Window(mingw/mingw64)</h4>
<p>Runtime query is implemented as follows:</p>
<pre><code>   typedef struct {
     char   fill;  // nibble one byte
                   // padding to align s1: padding_0 
     type_t s1;    // 
   } test_struct_type_t;
  
             padding_0 = sizeof(test_struct_type_t) - sizeof(type_t) - sizeof(char) ;
   alignmentOf(type_t) = sizeof(test_struct_type_t) - sizeof(type_t) ;</code></pre>
<table>
<thead>
<tr class="header">
<th style="text-align: left;">type</th>
<th style="text-align: left;">size <br> <em>32 bit</em></th>
<th style="text-align: left;">alignment <br> <em>32 bit</em></th>
<th style="text-align: left;">size <br> <em>64 bit</em></th>
<th style="text-align: left;">alignment <br> <em>64 bit</em></th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td style="text-align: left;">char</td>
<td style="text-align: left;">1</td>
<td style="text-align: left;">1</td>
<td style="text-align: left;">1</td>
<td style="text-align: left;">1</td>
</tr>
<tr class="even">
<td style="text-align: left;">short</td>
<td style="text-align: left;">2</td>
<td style="text-align: left;">2</td>
<td style="text-align: left;">2</td>
<td style="text-align: left;">2</td>
</tr>
<tr class="odd">
<td style="text-align: left;">int</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
</tr>
<tr class="even">
<td style="text-align: left;">float</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
</tr>
<tr class="odd">
<td style="text-align: left;">long</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">8†,4∗</td>
<td style="text-align: left;">8†,4∗</td>
</tr>
<tr class="even">
<td style="text-align: left;">pointer</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">4</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
</tr>
<tr class="odd">
<td style="text-align: left;">long long</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">4†,8∗+</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
</tr>
<tr class="even">
<td style="text-align: left;">double</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">4†,8∗+</td>
<td style="text-align: left;">8</td>
<td style="text-align: left;">8</td>
</tr>
<tr class="odd">
<td style="text-align: left;">long double</td>
<td style="text-align: left;">12†∗,8+,16-</td>
<td style="text-align: left;">4†∗,8+,16-</td>
<td style="text-align: left;">16</td>
<td style="text-align: left;">16</td>
</tr>
</tbody>
</table>
<p>† Linux, Darwin<br />
+armv7l-eabi<br />
- MacOsX-32bit-gcc4<br />
∗ Windows</p>
<h2 id="struct-mapping">Struct Mapping</h2>
<p>A <em>Struct</em> is a C compound type declaration, which can be
mapped to a Java class.</p>
<p>A <em>Struct</em> may utilize the following data types for its
fields</p>
<ul>
<li><em>Primitive</em>, i.e. <em>char</em>, <em>int32_t</em>, ...
<ul>
<li>See <a href="#primitive-mapping"><em>Primitive Mapping</em></a>
above.</li>
<li>See <a href="#string-mapping"><em>String Mapping</em></a>
above.</li>
</ul></li>
<li><em>Struct</em>, i.e. another compound variable</li>
<li><em>Function Pointer</em>, a <em>typedef</em>'ed and set callable
function pointer</li>
</ul>
<p>A field may be a direct aggregation, i.e. instance, within the struct
including an array or a reference to a single element or array via a
pointer.</p>
<p>Both, <em>primitive</em> and <em>struct</em> field type mappings only
produce pure Java code, utilizing the <em>GlueGen Runtime</em>. Hence no
additional native code must be compiled nor a resulting additional
library loaded to use the mapping.</p>
<p>Only when mapping <em>function-pointer</em> within <em>structs</em>,
additional native glue-code is produced to call the underlying native
function which has to be compiled and its library loaded.</p>
<p>The generated method
<code>public static boolean usesNativeCode()</code> can be used to
validate whether the produced Java class requires a corresponding
library for additional native code.</p>
<h3 id="gluegen-struct-settings">GlueGen Struct Settings</h3>
<h4 id="immutableaccess-symbol"><strong>ImmutableAccess</strong>
<em>symbol</em></h4>
<p>Immutable access can be set for a whole struct or a single field of a
struct.</p>
<p>Immutable access will simply suppress generating setters in the Java
code and hence also reduces the footprint of the generated Java class
for such struct.</p>
<ul>
<li><p><code>ImmutableAccess TK_Struct</code></p>
<p>Immutable access for the whole struct `TK_Struct</p>
<p>Sets pseudo-code flag <em>ImmutableAccess</em>, see below.</p></li>
<li><p><code>ImmutableAccess TK_Struct.val</code></p>
<p>Immutable access for the single field <code>val</code> within struct
<code>TK_Struct</code></p>
<p>Sets pseudo-code flag <em>ImmutableAccess</em>, see below.</p></li>
</ul>
<h4 id="maxoneelement-symbol"><strong>MaxOneElement</strong>
<em>symbol</em></h4>
<ul>
<li><p><code>MaxOneElement TK_Struct.val</code></p>
<p>Sets field pointer <code>val</code> to point to a array with a
maximum of one element and unset initial value (zero elements).</p>
<p>Sets pseudo-code flag <em>MaxOneElement</em>, see below.</p></li>
</ul>
<h4
id="returnedarraylength-symbol-expression"><strong>ReturnedArrayLength</strong>
<em>symbol</em> <em>expression</em></h4>
<ul>
<li><p><code>ReturnedArrayLength TK_Struct.val 3</code></p>
<p>Sets field pointer <code>val</code> to point to a array with three
elements.</p>
<p>Sets pseudo-code flag <em>ConstElemCount</em>, see below.</p>
<p>Having set <em>ConstElemCount</em> also implies <em>native
ownership</em> for a <em>Pointer</em> referenced <em>native</em>
memory.</p></li>
<li><p><code>ReturnedArrayLength TK_Struct.val 1</code></p>
<p>Sets field pointer <code>val</code> to point to a array with one
element.</p>
<p>Sets pseudo-code flags <em>ConstElemCount</em> and
<em>MaxOneElement</em>, see below.</p>
<p>Having set <em>ConstElemCount</em> also implies <em>native
ownership</em> for a <em>Pointer</em> referenced <em>native</em>
memory.</p></li>
<li><p><code>ReturnedArrayLength TK_Struct.val getValElements()</code></p>
<p>Sets field pointer <code>val</code> to point to a array with a
variable length as described by the field <code>valElements</code>
retrievable via its getter <code>getValElements()</code>.</p>
<p>Sets pseudo-code flag <em>VariaElemCount</em>, see below.</p></li>
</ul>
<h4 id="returnsstring-symbol"><strong>ReturnsString</strong>
<em>symbol</em></h4>
<p>A direct C code <code>char</code> array or indirect array via pointer
can be interpreted as a Java <code>String</code>.</p>
<ul>
<li><p><code>ReturnsString TK_Struct.name</code></p>
<p>Sets field char-array or char-pointer <code>name</code> to be
additionally interpreted as a Java <code>String</code>. Besides the
<code>byte[]</code> and <code>ByteBuffer</code> getter and setter
variants, a <code>String</code> variant will be added.</p>
<p>Sets pseudo-code flags <em>String</em>, see below.</p>
<p>See <a href="#string-mapping"><em>String Mapping</em></a>
above.</p></li>
</ul>
<h4 id="returnsstringonly-symbol"><strong>ReturnsStringOnly</strong>
<em>symbol</em></h4>
<ul>
<li><p><code>ReturnsStringOnly TK_Struct.name</code></p>
<p>Sets field char-array or char-pointer <code>name</code> to be
exclusively interpreted as a Java <code>String</code>. Instead of the
<code>byte[]</code> and <code>ByteBuffer</code> getter and setter
variants, a <code>String</code> variant will be produced.</p>
<p>Sets pseudo-code flags <em>StringOnly</em>, see below.</p>
<p>See <a href="#string-mapping"><em>String Mapping</em></a>
above.</p></li>
</ul>
<h3 id="struct-mapping-notes">Struct Mapping Notes</h3>
<ul>
<li><p><em>ConstElemCount</em> via <strong>ReturnedArrayLength
&lt;int&gt;</strong> implies <em>native ownership</em> for a
<em>Pointer</em> referenced <em>native</em> memory if the expression is
constant. Otherwise the <em>native</em> memory has <em>java
ownership</em>. See <a
href="#returnedarraylength-symbol-expression">ReturnedArrayLength
Setting</a> above.</p></li>
<li><p>To release native memory with <em>java ownership</em>, i.e. a
native ByteBuffer, <code>releaseVal()</code> can be used.</p></li>
<li><p>To shrink a <em>Pointer</em> &amp; <em>VariaElemCount</em>
pointer-array elemCount size with <em>java ownership</em> , the memory
must be cleared with <code>releaseVal()</code> first. This is due to
<code>setVal(src, srcPos, destPos, len)</code> reusing the existing
memory in case <code>destPos + len &lt; elemCount</code>.</p></li>
</ul>
<h3 id="struct-java-signature-table">Struct Java Signature Table</h3>
<p>Please find below signature table as generated by the <em>C
Declaration</em> including its <em>C Modifier</em>, e.g.
<code>const</code> for constant, <code>[const]</code> for const and
non-const and <code>empty</code> for non-const (variable).</p>
<p>Further, the <em>GlueGen Setting</em> (see above) impacts the code
generation as well.</p>
<p>Below table demonstrates <em>primitive</em> types being mapped within
a <code>struct</code> named <code>TK_Struct</code>. A similar mapping is
produced for <code>struct</code> types, i.e. <em>compounds</em>.</p>
<table>
<thead>
<tr class="header">
<th style="text-align: left;">C Mod</th>
<th style="text-align: left;">C Declaration</th>
<th style="text-align: left;">Java Setter</th>
<th style="text-align: left;">Java Getter</th>
<th style="text-align: left;">GlueGen Setting</th>
<th style="text-align: left;">Ownership</th>
<th style="text-align: left;">Remarks</th>
</tr>
</thead>
<tbody>
<tr class="odd">
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">static boolean usesNativeCode()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java, static, <br> <em>true</em> if using
native code</td>
</tr>
<tr class="even">
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">static int size()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java, static, <br> native size in
bytes</td>
</tr>
<tr class="odd">
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">static TK_Struct create()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java, static ctor</td>
</tr>
<tr class="even">
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">static TK_Struct create(ByteBuffer)</td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java, static ctor <br> w/ existing
ByteBuffer</td>
</tr>
<tr class="odd">
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">static TK_Struct derefPointer(long
addr)</td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java, static ctor <br> dereferencing
ByteBuffer <br> at native address of size()</td>
</tr>
<tr class="even">
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">ByteBuffer getBuffer()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java, <br> underlying ByteBuffer</td>
</tr>
<tr class="odd">
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">long getDirectBufferAddress()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java, native address <br> of underlying
getBuffer()</td>
</tr>
<tr class="even">
<td style="text-align: left;"></td>
<td style="text-align: left;">int32_t val</td>
<td style="text-align: left;">setVal(int v)</td>
<td style="text-align: left;">int getVal()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Static</td>
<td style="text-align: left;"></td>
</tr>
<tr class="odd">
<td style="text-align: left;">const</td>
<td style="text-align: left;">int32_t val</td>
<td style="text-align: left;"><em>none</em></td>
<td style="text-align: left;">int getVal()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Static</td>
<td style="text-align: left;">Read only</td>
</tr>
<tr class="even">
<td style="text-align: left;"></td>
<td style="text-align: left;">int32_t val</td>
<td style="text-align: left;"><em>none</em></td>
<td style="text-align: left;">int getVal()</td>
<td style="text-align: left;"><strong>ImmutableAccess</strong></td>
<td style="text-align: left;">Static</td>
<td style="text-align: left;">Read only</td>
</tr>
<tr class="odd">
<td style="text-align: left;">[const]</td>
<td style="text-align: left;">int32_t* val</td>
<td style="text-align: left;">setVal(int v) <br> releaseVal()</td>
<td style="text-align: left;">int getVal() <br> boolean isValNull() <br>
int getValElemCount()</td>
<td style="text-align: left;"><strong>MaxOneElement</strong></td>
<td style="text-align: left;">Java</td>
<td style="text-align: left;">Starts w/ null elements,<br>max 1
element</td>
</tr>
<tr class="even">
<td style="text-align: left;">const</td>
<td style="text-align: left;">int32_t* val</td>
<td style="text-align: left;"><em>none</em></td>
<td style="text-align: left;">int getVal() <br> boolean isValNull() <br>
static int getValElemCount()</td>
<td style="text-align: left;"><strong>ReturnedArrayLength
1</strong></td>
<td style="text-align: left;">Native</td>
<td style="text-align: left;">Const element count 1</td>
</tr>
<tr class="odd">
<td style="text-align: left;"></td>
<td style="text-align: left;">int32_t* val</td>
<td style="text-align: left;">setVal(int v)</td>
<td style="text-align: left;">int getVal() <br> boolean isValNull() <br>
static int getValElemCount()</td>
<td style="text-align: left;"><strong>ReturnedArrayLength
1</strong></td>
<td style="text-align: left;">Native</td>
<td style="text-align: left;">Const element count 1</td>
</tr>
<tr class="even">
<td style="text-align: left;"></td>
<td style="text-align: left;">int32_t val[3]</td>
<td style="text-align: left;">setVal(int[] src, int srcPos, int destPos,
int len)</td>
<td style="text-align: left;">IntBuffer getVal() <br> int[] getVal(int
srcPos, int[] dest, int destPos, int len)</td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Static</td>
<td style="text-align: left;"></td>
</tr>
<tr class="odd">
<td style="text-align: left;">const</td>
<td style="text-align: left;">int32_t val[3]</td>
<td style="text-align: left;"><em>none</em></td>
<td style="text-align: left;">IntBuffer getVal() <br> int[] getVal(int
srcPos, int[] dest, int destPos, int len)</td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Static</td>
<td style="text-align: left;">Read only</td>
</tr>
<tr class="even">
<td style="text-align: left;">const</td>
<td style="text-align: left;">int32_t* val</td>
<td style="text-align: left;"><em>none</em></td>
<td style="text-align: left;">IntBuffer getVal() <br> int[] getVal(int
srcPos, int[] dest, int destPos, int len) <br> boolean isValNull() <br>
static int getValElemCount()</td>
<td style="text-align: left;"><strong>ReturnedArrayLength
3</strong></td>
<td style="text-align: left;">Native</td>
<td style="text-align: left;">Read only <br> Const element count 3</td>
</tr>
<tr class="odd">
<td style="text-align: left;"></td>
<td style="text-align: left;">int32_t* val</td>
<td style="text-align: left;">setVal(int[] src, int srcPos, int destPos,
int len)</td>
<td style="text-align: left;">IntBuffer getVal() <br> int[] getVal(int
srcPos, int[] dest, int destPos, int len) <br> boolean isValNull() <br>
static int getValElemCount()</td>
<td style="text-align: left;"><strong>ReturnedArrayLength
3</strong></td>
<td style="text-align: left;">Native</td>
<td style="text-align: left;">Const element count 3</td>
</tr>
<tr class="even">
<td style="text-align: left;">[const]</td>
<td style="text-align: left;">int32_t* val</td>
<td style="text-align: left;">setVal(int[] src, int srcPos, int destPos,
int len) <br> releaseVal()</td>
<td style="text-align: left;">IntBuffer getVal() <br> int[] getVal(int
srcPos, int[] dest, int destPos, int len) <br> boolean isValNull() <br>
int getValElemCount()</td>
<td style="text-align: left;"></td>
<td style="text-align: left;">Java</td>
<td style="text-align: left;">Starts w/ null elements</td>
</tr>
<tr class="odd">
<td style="text-align: left;">[const]</td>
<td style="text-align: left;">int32_t* val</td>
<td style="text-align: left;">setVal(int[] src, int srcPos, int destPos,
int len) <br> releaseVal()</td>
<td style="text-align: left;">IntBuffer getVal() <br> int[] getVal(int
srcPos, int[] dest, int destPos, int len) <br> boolean isValNull()</td>
<td style="text-align: left;"><strong>ReturnedArrayLength
getValCount()</strong></td>
<td style="text-align: left;"><em>Ambiguous</em></td>
<td style="text-align: left;">Variable element count<br>using field
<em>valCount</em>,<br>which has getter and setter</td>
</tr>
<tr class="even">
<td style="text-align: left;">[const]</td>
<td style="text-align: left;">char* name</td>
<td style="text-align: left;">setName(String srcVal) <br>
releaseVal()</td>
<td style="text-align: left;">String getName() <br> boolean isNameNull()
<br> int getNameElemCount()</td>
<td style="text-align: left;"><strong>ReturnsStringOnly</strong></td>
<td style="text-align: left;">Java</td>
<td style="text-align: left;">String only, w/ EOS</td>
</tr>
<tr class="odd">
<td style="text-align: left;">[const]</td>
<td style="text-align: left;">char* name</td>
<td style="text-align: left;">setName(String srcVal) <br> setName(byte[]
src, int srcPos, int destPos, int len) <br> releaseVal()</td>
<td style="text-align: left;">String getNameAsString() <br> ByteBuffer
getName() <br> boolean isNameNull() <br> int getNameElemCount()</td>
<td style="text-align: left;"><strong>ReturnsString</strong></td>
<td style="text-align: left;">Java</td>
<td style="text-align: left;">String and byte access, w/ EOS</td>
</tr>
</tbody>
</table>
<h3 id="struct-setter-pseudo-code">Struct Setter Pseudo-Code</h3>
<ul>
<li><em>ImmutableAccess</em>: Drops setter, immutable</li>
<li><em>Pointer</em> &amp; <em>ConstValue</em> &amp;
<em>ConstElemCount</em>: Drops setter, native ownership on
const-value</li>
<li><em>Array</em> &amp; <em>ConstValue</em> : Drops setter, const-value
array</li>
<li><em>Primitive</em>
<ul>
<li>Single aggregated instance
<ul>
<li>Store value within <em>native</em> memory</li>
</ul></li>
<li><em>Array</em> | <em>Pointer</em>
<ul>
<li><em>MaxOneElement</em>
<ul>
<li><em>Pointer</em>
<ul>
<li><em>ConstValue</em>: Allocate new memory and store value</li>
<li><em>VariaValue</em>:
<ul>
<li><em>ConstElemCount</em>: Reuse <em>native</em> memory and store
value with matching <em>elemCount 1</em>, otherwise Exception</li>
<li><em>VariaElemCount</em>: Reuse <em>native</em> memory and store
value with matching <em>elemCount 1</em>, otherwise allocates new memory
(had <em>elemCount 0</em>)</li>
</ul></li>
</ul></li>
<li><em>Array</em> &amp; <em>VariaValue</em>: Reuse <em>native</em>
memory and store value (has const <em>elemCount 1</em>)</li>
<li><em>else</em>: <em>SKIP</em> setter for const single-primitive
array</li>
</ul></li>
<li><em>AnyElementCount</em>
<ul>
<li><em>String</em> &amp; <em>isByteBuffer</em> &amp; <em>Pointer</em>
<ul>
<li><em>ConstElemCount</em>: Reuse <em>native</em> memory and store
UTF-8 bytes with EOS with matching <em>elemCount</em>, otherwise
Exception
<ul>
<li><em>StringOnly</em>: End, no more setter for this field, otherwise
continue</li>
</ul></li>
<li><em>VariaElemCount</em>: Allocate new <em>native</em> memory and
store UTF-8 bytes with EOS
<ul>
<li><em>StringOnly</em>: End, no more setter for this field, otherwise
continue</li>
</ul></li>
</ul></li>
<li><em>ConstValue</em>
<ul>
<li><em>Pointer</em>
<ul>
<li><em>VariaElemCount</em>: Allocates new <em>native</em> memory and
store value</li>
</ul></li>
<li><em>else</em>: <em>SKIP</em> setter for const primitive array</li>
</ul></li>
<li><em>Array</em> | <em>ConstElemCount</em>: Reuse <em>native</em>
memory and store value with &lt;= <em>elemCount</em>, otherwise
Exception</li>
<li><em>Pointer</em> &amp; <em>VariaElemCount</em>: Reuse
<em>native</em> memory and store value with &lt;= <em>elemCount</em>,
otherwise allocate new <em>native</em> memory</li>
</ul></li>
</ul></li>
</ul></li>
<li><em>Struct</em> ...</li>
</ul>
<h2 id="platform-header-files">Platform Header Files</h2>
<p>GlueGen provides convenient platform headers,<br />
which can be included in your C header files for native compilation and
GlueGen code generation.</p>
<p>Example:</p>
<pre><code>   #include &lt;gluegen_stdint.h&gt;
   #include &lt;gluegen_stddef.h&gt;
 
   uint64_t test64;
   size_t size1;
   ptrdiff_t ptr1;</code></pre>
<p>To compile this file you have to include the following folder to your
compilers system includes, ie <code>-I</code>:</p>
<pre><code>    gluegen/make/stub_includes/platform</code></pre>
<p>To generate code for this file you have to include the following
folder to your GlueGen <code>includeRefid</code> element:</p>
<pre><code>    gluegen/make/stub_includes/gluegen</code></pre>
<h2 id="pre-defined-macros">Pre-Defined Macros</h2>
<p>To identity a GlueGen code generation run, GlueGen defines the
following macros:</p>
<pre><code>     #define __GLUEGEN__ 2</code></pre>