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-rw-r--r--src/java/com/jogamp/gluegen/package.html25
1 files changed, 18 insertions, 7 deletions
diff --git a/src/java/com/jogamp/gluegen/package.html b/src/java/com/jogamp/gluegen/package.html
index 449eb31..5e86aad 100644
--- a/src/java/com/jogamp/gluegen/package.html
+++ b/src/java/com/jogamp/gluegen/package.html
@@ -42,8 +42,9 @@
<h4>GlueGen Internal Alignment for Compound Data</h4>
In general, depending on CPU and it's configuration (OS), alignment is set up
- for each type (char, short, int, long, ..),<br>
- where structures are aligned naturally, i.e. their inner components are aligned.<br>
+ for each type (char, short, int, long, ..).
+ <p>Compounds (structures) are aligned naturally, i.e. their inner components are aligned<br>
+ and are itself aligned to it's largest element.</p>
See:<br>
<ul>
<li><a href="http://en.wikipedia.org/wiki/Data_structure_alignment">Wikipedia Data Structure Alignment</a></li>
@@ -52,18 +53,28 @@
<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>
+ <h5>Simple alignment arithmetic</h5>
+ <blockquote>remainder = net_size % alignment</blockquote>
+ since alignment is a multiple of 2 <code>-> x % 2n == x & (2n - 1)</code><br>
+ <blockquote>remainder = net_size & ( alignment - 1 )</blockquote>
+ <blockquote>
+ padding = alignment - remainder ;<br>
+ aligned_size = net_size + padding ;
+ </blockquote>
+
<h5>Type Size &amp; Alignment for x86, x86_64, armv7l-32bit-eabi and Window(mingw/mingw64)</h5>
Runtime query is implemented as follows:
<pre>
typedef struct {
char fill; // nibble one byte
- // padding to align s1
- _TYPE_ s1; //
- } type_t;
+ // padding to align s1: padding_0
+ type_t s1; //
+ } test_struct_type_t;
- padding = sizeof(type_t) - sizeof(_TYPE_) - sizeof(char);
- alignment = sizeof(type_t) - sizeof(_TYPE_) ;
+ padding_0 = sizeof(test_struct_type_t) - sizeof(type_t) - sizeof(char) ;
+ alignmentOf(type_t) = sizeof(test_struct_type_t) - sizeof(type_t) ;
</pre>
+
<table border="1">
<tr><th>type</th> <th colspan="2">32 bits</th><th colspan="2">64 bits</th></tr>
<tr><th></th> <th>size</th><th>alignment</th><th>size</th><th>alignment</th></tr>