GlueGen Code Generator

JogAmp GlueGen Code Generator

GlueGen Data Type Mapping

Gluegen has build-in types (terminal symbols) for:

type	java bits	native bits		type	signed	origin
		x32	x64
void	0	0	0	void	void	ANSI-C
char	8	8	8	integer	any	ANSI-C
short	16	16	16	integer	any	ANSI-C
int	32	32	32	integer	any	ANSI-C
long	64	32	32¹	integer	any	ANSI-C - Windows
long	64	32	64	integer	any	ANSI-C - Unix
float	32	32	32	float	signed	ANSI-C
double	64	64	64	double	signed	ANSI-C
__int32	32	32	32	integer	any	windows
__int64	64	64	64	integer	any	windows
int8_t	8	8	8	integer	signed	stdint.h
uint8_t	8	8	8	integer	unsigned	stdint.h
int16_t	16	16	16	integer	signed	stdint.h
uint16_t	16	16	16	integer	unsigned	stdint.h
int32_t	32	32	32	integer	signed	stdint.h
uint32_t	32	32	32	integer	unsigned	stdint.h
int64_t	64	64	64	integer	signed	stdint.h
uint64_t	64	64	64	integer	unsigned	stdint.h
intptr_t	64	32	64	integer	signed	stdint.h
uintptr_t	64	32	64	integer	unsigned	stdint.h
ptrdiff_t	64	32	64	integer	signed	stddef.h
size_t	64	32	64	integer	unsigned	stddef.h
wchar_t	32	32	32	integer	signed	stddef.h

Warning: Try to avoid unspecified bit sized types, especially long, since it differs on Unix and Windows!
Notes:

Type long will result in broken code on Windows, since we don't differentiate the OS and it's bit size is ambiguous.
Anonymous void-pointer void* are mapped to NIO Buffer.
Pointers to pointer-size types like intptr_t*, uintptr_t*, ptrdiff_t* and size_t* are mapped to PointerBuffer, to reflect the architecture depending storage size.

GlueGen Internal Alignment for Compound Data

In general, depending on CPU and it's configuration (OS), alignment is set up for each type (char, short, int, long, ..).

Compounds (structures) are aligned naturally, i.e. their inner components are aligned
and are itself aligned to it's largest element.

See:

Simple alignment arithmetic

Modulo operation, where the 2nd handles the case offset == alignment:

padding = ( alignment - ( offset % alignment ) ) % alignment ;
aligned_offset = offset + padding ;

Optimization utilizing alignment as a multiple of 2 -> x % 2n == x & ( 2n - 1 )

remainder = offset & ( alignment - 1 ) ;
padding = ( remainder > 0 ) ? alignment - remainder : 0 ;
aligned_offset = offset + padding ;

Without branching, using the 2nd modulo operation for the case offset == alignment:

padding = ( alignment - ( offset & ( alignment - 1 ) ) ) & ( alignment - 1 ) ;
aligned_offset = offset + padding ;

See com.jogamp.gluegen.cgram.types.SizeThunk.align(..).

Type Size & Alignment for x86, x86_64, armv6l-32bit-eabi and Window(mingw/mingw64)

Runtime query is implemented as follows:

   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) ;

type	32 bits		64 bits
	size	alignment	size	alignment
char	1	1	1	1
short	2	2	2	2
int	4	4	4	4
float	4	4	4	4
long	4	4	8^†,4^∗	8^†,4^∗
pointer	4	4	8	8
long long	8	4^†,8^∗⁺	8	8
double	8	4^†,8^∗⁺	8	8
long double	12^†^∗,8⁺,16^-	4^†^∗,8⁺,16^-	16	16

^† Linux, Darwin
⁺armv7l-eabi
^- MacOsX-32bit-gcc4
^∗ Windows

GlueGen Platform Header Files

GlueGen provides convenient platform headers,
which can be included in your C header files for native compilation and GlueGen code generation.

Example:

   #include <gluegen_stdint.h>
   #include <gluegen_stddef.h>
 
   uint64_t test64;
   size_t size1;
   ptrdiff_t ptr1;

To compile this file you have to include the following folder to your compilers system includes, ie -I:

    gluegen/make/stub_includes/platform

To generate code for this file you have to include the following folder to your GlueGen includeRefid element:

    gluegen/make/stub_includes/gluegen

GlueGen Pre-Defined Macros

To identity a GlueGen code generation run, GlueGen defines the following macros:

     #define __GLUEGEN__ 2