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| -rw-r--r-- | src/java/com/jogamp/gluegen/package.html | 25 |
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 & 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 & 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> |