Host. More...

Defines
#define	VL_YESNO(x) ((x)?"yes":"no")
	Convert a boolean to "yes" or "no" strings.
Configuration options
#define	VL_DISABLE_THREADS
	Defined if multi-threading support is disabled.
#define	VL_DISABLE_SSE2
	Defined if SSE2 support if disabled.
Defining functions
#define	VL_EXPORT
	Declares a DLL exported symbol.
#define	VL_INLINE
	Adds appropriate inline function qualifier.
C preprocessor helper macros
#define	VL_STRINGIFY(x) # x
	Convert the argument to a string.
#define	VL_XSTRINGIFY(x) VL_STRINGIFY(x)
	Expand and then convert the argument to a string.
#define	VL_CAT(x, y) x ## y
	Concatenate two arguments into a lexical unit.
#define	VL_XCAT(x, y) VL_CAT(x,y)
	Expand and then concatenate two arguments into a lexical unit.
#define	VL_XCAT3(x, y, z) VL_XCAT(VL_XCAT(x,y),z)
	Expand and then concatenate three arguments into a lexical unit.
#define	VL_XCAT4(x, y, z, u) VL_XCAT(VL_XCAT3(x,y,z),u)
	Expand and then concatenate four arguments into a lexical unit.
#define	VL_XCAT5(x, y, z, u, v) VL_XCAT(VL_XCAT4(x,y,z,u),v)
	Expand and then concatenate five arguments into a lexical unit.
Identifying the host operating system
#define	VL_OS_LINUX 1
	Defined if the host operating system is Linux.
#define	VL_THREADS_POSIX 1
#define	VL_OS_MACOSX 1
	Defined if the host operating system is Mac OS X.
#define	VL_THREADS_POSIX 1
#define	VL_OS_WIN 1
	Defined if the host operating system is Windows (32 or 64)
#define	VL_THREADS_WIN 1
#define	VL_OS_WIN64 1
	Defined if the host operating system is Windows-64.
#define	VL_THREADS_WIN 1
Identifying the host compiler
#define	VL_COMPILER_GNUC
	Defined if the host compiler is GNU C.
#define	VL_COMPILER_MSC _MSC_VER
	Defined if the host compiler is Microsoft Visual C++.
#define	VL_COMPILER_LCC 1
Identifying the host CPU architecture
#define	VL_ARCH_IX86 300
	Defined if the host CPU is of the Intel x86 family.
#define	VL_ARCH_IA64
	Defined if the host CPU is of the Intel Architecture-64 family.
Identifying the host data model
#define	VL_COMPILER_LLP64
	Defined if the host compiler data model is LLP64.
#define	VL_COMPILER_LP64
	Defined if the host compiler data model is LP64.
#define	VL_COMPILER_ILP32
	Defined if the host compiler data model is ILP32.
Identifying the host endianness
#define	VL_ARCH_LITTLE_ENDIAN
	Defined if the host CPU is little endian.
#define	VL_ARCH_BIG_ENDIAN
	Defined if the host CPU is big endian.
Printing the atomic data types
#define	VL_FL_INT64 "I64"
	`printf` length flag for vl_int64 and vl_uint64.
#define	VL_FL_INT32 ""
	`printf` length flag for vl_int32 and vl_uint32.
#define	VL_FL_INT16 "h"
	`printf` length flag for vl_int16 and vl_uint16.
#define	VL_FL_INT8 "hh"
	`printf` length flag for vl_int8 and vl_uint8.
#define	VL_FL_INDEX VL_FL_INT64
	`printf` length flag for vl_index and vl_uindex
#define	VL_FL_INDEX VL_FL_INT32
	`printf` length flag for vl_index and vl_uindex
#define	VL_FMT_INDEX VL_FL_INDEX "d"
	`printf` flag for vl_index
#define	VL_FMT_INTPTR VL_FMT_INDEX
	`printf` flag for vl_intptr
#define	VL_FMT_UINDEX VL_FL_INDEX "u"
	`printf` flag for vl_uindex
#define	VL_FMT_SIZE VL_FMT_UINDEX
	`printf` flag for vl_size
#define	VL_FMT_UINTPTR VL_FMT_UINDEX
	`printf` flag for vl_uintptr
Atomic data types limits
#define	VL_BIG_INT 0x7FFFFFFFL
	Largest integer (math constant)
#define	VL_SMALL_INT (- VL_BIG_INT - 1)
	Smallest integer (math constant)
#define	VL_BIG_UINT 0xFFFFFFFFUL
	Largest unsigned integer (math constant)
Functions
char *	vl_static_configuration_to_string_copy ()
	Human readable static library configuration.
Endianness detection and conversion
void	vl_swap_host_big_endianness_8 (void dst, void src)
	Host <-> big endian transformation for 8-bytes value.
void	vl_swap_host_big_endianness_4 (void dst, void src)
	Host <-> big endian transformation for 4-bytes value.
void	vl_swap_host_big_endianness_2 (void dst, void src)
	Host <-> big endian transformation for 2-bytes value.
Obtaining host info at run time
void	_vl_x86cpu_info_init (VlX86CpuInfo *self)
char *	_vl_x86cpu_info_to_string_copy (VlX86CpuInfo const *self)
Atomic data types
#define	VL_TRUE 1
	`true` (1) constant
#define	VL_FALSE 0
	`false` (0) constant
typedef long long	vl_int64
	Signed 64-bit integer.
typedef int	vl_int32
	Signed 32-bit integer.
typedef short	vl_int16
	Signed 16-bit integer.
typedef char	vl_int8
	Signed 8-bit integer.
typedef long long unsigned	vl_uint64
	Unsigned 64-bit integer.
typedef int unsigned	vl_uint32
	Unsigned 32-bit integer.
typedef short unsigned	vl_uint16
	Unsigned 16-bit integer.
typedef char unsigned	vl_uint8
	Unsigned 8-bit integer.
typedef int	vl_int
	Same as `int`.
typedef unsigned int	vl_uint
	Same as `unsigned int`.
typedef int	vl_bool
	Boolean.
typedef vl_int64	vl_intptr
	Integer holding a pointer.
typedef vl_uint64	vl_uintptr
	Unsigned integer holding a pointer.
typedef vl_uint64	vl_size
	Unsigned integer holding the size of a memory block.
typedef vl_int64	vl_index
	Signed version of vl_size and vl_uindex.
typedef vl_uint64	vl_uindex
	Same as vl_size.

Detailed Description

This module provides functionalities to identify the host operating system, C compiler, and CPU architecture. It also provides a few features to abstract from such details.

See also:: http://predef.sourceforge.net/index.php

Host operating system

The module defines a symbol to identify the host operating system: VL_OS_WIN for Windows, VL_OS_LINUX for Linux, VL_OS_MACOSX for Mac OS X, and so on.

Host compiler

The module defines a symbol to identify the host compiler: VL_COMPILER_MSC for Microsoft Visual C++, VL_COMPILER_GNUC for GNU C, and so on. The (integer) value of such symbols corresponds the version of the compiler.

The module defines a symbol to identify the data model of the compiler: VL_COMPILER_ILP32, VL_COMPILER_LP64, or VL_COMPILER_LLP64 (see Sect. Data models). For convenience, it also defines a number of atomic types of prescribed width (vl_int8, vl_int16, vl_int32, etc.).

Remarks:: While some of such functionalities are provided by the standard header stdint.h, the latter is not supported by all platforms.

Data models

The C language defines a number of atomic data types (such as char, short, int and so on). The number of bits (width) used to represent each data type depends on the compiler data model. The following table summarizes the relevant conventions:

**Compiler data models.** The table shows how many bits are allocated to each atomic data type according to each model.
Data model	`short`	`int`	`long`	`long long`	`void*`	Compiler
ILP32	16	32	32	64	32	common 32 bit architectures
LP64	16	32	64	64	64	UNIX-64 (Linux, Mac OS X)
ILP64	16	64	64	64	64	Alpha, Cray
SLIP64	64	64	64	64	64
LLP64	16	32	32	64	64	Windows-64

Other compiler-specific features

The module provides the macro VL_EXPORT to declare symbols exported from the library and the macro VL_INLINE to declare inline functions. Such features are not part of the C89 standard, and change depending on the compiler.

Example:

The following header file declares a function f that should be visible from outside the library.

 #include <vl/generic.h>
 VL_EXPORT void f () ;
 VL_EXPORT int i ;

Notice that the macro VL_EXPORT needs not to be included again when the function is defined.

Example:

The following header file declares an inline function f:

 #include <vl/generic.h>
 VL_INLINE int f() ;

 VL_INLINE int f() { return 1 ; }

Here the first instruction defines the function f, where the second declares it. Notice that since this is an inline function, its definition must be found in the header file rather than in an implementation file. Notice also that definition and declaration can be merged.

These macros translate according to the following tables:

Macros for exporting library symbols
Platform	Macro name	Value when building the library	Value when importing the library
Unix/GCC	VL_EXPORT	empty (assumes `-visibility=hidden` GCC option)	`__attribute__((visibility ("default")))`
Win/Visual C++	VL_EXPORT	`__declspec(dllexport)`	`__declspec(dllimport)`

Macros for declaring inline functions
Platform	Macro name	Value
Unix/GCC	VL_INLINE	static inline
Win/Visual C++	VL_INLINE	static __inline

Host CPU architecture

The module defines a symbol to identify the host CPU architecture: VL_ARCH_IX86 for Intel x86, VL_ARCH_IA64 for Intel 64, and so on.

Endianness

The module defines a symbol to identify the host CPU endianness: VL_ARCH_BIG_ENDIAN for big endian and VL_ARCH_LITTLE_ENDIAN for little endian. The functions vl_swap_host_big_endianness_8(), vl_swap_host_big_endianness_4(), vl_swap_host_big_endianness_2() to change the endianness of data (from/to host and network order).

Recall that endianness concerns the way multi-byte data types (such as 16, 32 and 64 bits integers) are stored into the addressable memory. All CPUs uses a contiguous address range to store atomic data types (e.g. a 16-bit integer could be assigned to the addresses 0x10001 and 0x10002), but the order may differ.

The convention is big endian, or in network order, if the most significant byte of the multi-byte data types is assigned to the smaller memory address. This is the convention used for instance by the PPC architecture.

The convention is little endian if the least significant byte is assigned to the smaller memory address. This is the convention used for instance by the x86 architecture.

Remarks:: The names “big endian” and “little endian” are a little confusing. “Big endian” means “big endian first”, i.e. the address of the most significant byte comes first. Similarly, “little endian” means “little endian first”, in the sense that the address of the least significant byte comes first.

Endianness is a concern when data is either exchanged with processors that use different conventions, transmitted over a network, or stored to a file. For the latter two cases, one usually saves data in big endian (network) order regardless of the host CPU.

host-threads

The file defines #VL_THREADS_WIN if multi-threading support is enabled and the host supports Windows threads and #VL_THREADS_POSIX if it supports POSIX threads.

Author:: Andrea Vedaldi

Define Documentation

#define VL_ARCH_BIG_ENDIAN

See also:: Endianness

#define VL_ARCH_IA64

See also:: Host CPU architecture

#define VL_ARCH_IX86 300

See also:: Host CPU architecture

#define VL_ARCH_LITTLE_ENDIAN

See also:: Endianness

#define VL_CAT	(	x,
		y
	)	x ## y

Parameters:

x	first argument to be concatenated.
y	second argument to be concatenated.

This macro concatenates its arguments into a single lexical unit by means of the ## preprocessor operator. Notice that arguments concatenated by ## are not pre-expanded by the C preprocessor. To macro-expand the arguments and then concatenate them,use VL_XCAT.

See also:: VL_XCAT

#define VL_COMPILER_GNUC

Value:

(__GNUC__ * 10000 \
+ __GNUC_MINOR__ * 100)

This macro is defined if the compiler is GNUC. Its value is calculated as

 10000 * MAJOR + 100 * MINOR + PATCHLEVEL

See also:: Host compiler

#define VL_COMPILER_ILP32

See also:: Data models

#define VL_COMPILER_LLP64

See also:: Data models

#define VL_COMPILER_LP64

See also:: Data models

#define VL_COMPILER_MSC _MSC_VER

See also:: Host compiler

#define VL_DISABLE_SSE2

Define this symbol to disable SSE2 support.

#define VL_DISABLE_THREADS

Define this symbol to disable multi-threading support.

#define VL_EXPORT

See also:: Other compiler-specific features

#define VL_INLINE

See also:: Other compiler-specific features

#define VL_STRINGIFY ( x ) # x

Parameters:

x	value to be stringified.

This macro stringifies the argument x by means of the # prerpocessor operator.

The standard C preprocessor does not prescan arguments which are stringified, so

 #define A B
 char const * str = VL_STRINGIFY(A) ;

initializes str with a pointer to the string "A", which mihgt be unexpected. To fix this issue, you can use VL_XSTRINGIFY.

See also:: VL_XSTRINGIFY

#define VL_XCAT	(	x,
		y
	)	VL_CAT(x,y)

Parameters:

x	first argument to be concatenated.
y	second argument to be concatenated.

This macro is the same as VL_CAT, except that the arguments are macro expanded before being concatenated.

See also:: VL_CAT

#define VL_XCAT3	(	x,
		y,
		z
	)	VL_XCAT(VL_XCAT(x,y),z)

Parameters:

x	first argument to be concatenated.
y	second argument to be concatenated.
z	third argument to be concatenated.

This macro is the same as VL_XCAT, except that it has three arguments.

See also:: VL_XCAT

#define VL_XCAT4	(	x,
		y,
		z,
		u
	)	VL_XCAT(VL_XCAT3(x,y,z),u)

Parameters:

x	first argument to be concatenated.
y	second argument to be concatenated.
z	third argument to be concatenated.
u	fourth argument to be concatenated.

This macro is the same as VL_XCAT, except that it has four arguments.

See also:: VL_XCAT

#define VL_XCAT5	(	x,
		y,
		z,
		u,
		v
	)	VL_XCAT(VL_XCAT4(x,y,z,u),v)

Parameters:

x	first argument to be concatenated.
y	second argument to be concatenated.
z	third argument to be concatenated.
u	fourth argument to be concatenated.
v	fifth argument to be concatenated.

This macro is the same as VL_XCAT, except that it has five arguments.

See also:: VL_XCAT

#define VL_XSTRINGIFY ( x ) VL_STRINGIFY(x)

Parameters:

x	value to be macro-expanded and converted.

This macro macro-expands the argument x and stringifies the result of the expansion. For instance

 #define A B
 char const * str = VL_STRINGIFY(A) ;

initializes str with a pointer to the string "B".

See also:: VL_STRINGIFY

#define VL_YESNO ( x ) ((x)?"yes":"no")

Parameters:

x	boolean to convert. A pointer to either the string "yes" (if x is true) or the string "no".

Example

 VL_PRINTF("Is x true? %s.", VL_YESNO(x))

Function Documentation

char* vl_static_configuration_to_string_copy ( )

Returns:: a new string with the static configuration.

The string includes information about the compiler, the host, and other static configuration parameters. The string must be released by vl_free.

void vl_swap_host_big_endianness_2	(	void *	dst,
		void *	src
	)		`[inline]`

Parameters:

dst	destination 2-byte buffer.
src	source 2-byte bufffer.

See also:: Endianness.

void vl_swap_host_big_endianness_4	(	void *	dst,
		void *	src
	)		`[inline]`

Parameters:

dst	destination 4-byte buffer.
src	source 4-byte bufffer.

See also:: Endianness.

void vl_swap_host_big_endianness_8	(	void *	dst,
		void *	src
	)		`[inline]`

Parameters:

dst	destination 8-byte buffer.
src	source 8-byte bufffer.

See also:: Endianness.

VLFeat.org

Defines

Functions

Atomic data types

Detailed Description

Host operating system

Host compiler

Data models

Other compiler-specific features

Host CPU architecture

Endianness

host-threads

Define Documentation

Function Documentation