GDT::Pointer Struct Reference

Structure that describes a GDT Pointer (aka GDT Descriptor). More...

#include <machine/gdt.h>

Public Member Functions
template<typename T, size_t LEN>
constexpr	Pointer (const T(&desc)[LEN])
	Constructor (automatic length).
constexpr	Pointer (void *desc, size_t len)
	Constructor.
void	set (void *desc, size_t len)
	Set an address.

Public Attributes
uint16_t	limit
	GDT size in bytes (minus 1 byte).
void *	base
	GDT base address.

Detailed Description

Structure that describes a GDT Pointer (aka GDT Descriptor).

It contains both the length (in bytes) of the GDT (minus 1 byte) and the pointer to the GDT. The pointer to the GDT can be loaded using the instruction lgdt.

Note

As Intel uses little endian for representing multi-byte values, the GDT::Pointer structure can be used for 16, 32, and 64 bit descriptor tables:

*         | 16 bit | 16 bit  | 16 bit  | 16 bit  | 16 bit  |
*         +--------+---------------------------------------+
* Pointer | limit  | base (up to 64 bit)                   |
*         +--------+---------+---------+---------+---------+
*         | used for 16 bit  | ignored...                  |
*         |      used for 32 bit       | ignored...        |
*         |                used for 64 bit                 |
*        

See also

ISDMv3, Figure 2-6; Memory Management Registers

Constructor & Destructor Documentation

Pointer() [1/2]

template<typename T, size_t LEN>

GDT::Pointer::Pointer ( const T(&) desc[LEN] )

inlineexplicitconstexpr

Constructor (automatic length).

Parameters

desc	Array of GDT segment descriptors – must be defined in the same module!

Pointer() [2/2]

GDT::Pointer::Pointer ( void * desc, size_t len )

inlineconstexpr

Constructor.

Parameters

desc	Address of the GDT segment descriptors
len	Number of entries

Member Function Documentation

set()

void GDT::Pointer::set ( void * desc, size_t len )

inline

Set an address.

Note

On change, lgdt must be executed again

Parameters

desc	Address of the GDT segment descriptors
len	Number of entries

Member Data Documentation

limit

uint16_t GDT::Pointer::limit

GDT size in bytes (minus 1 byte).

base

void* GDT::Pointer::base

GDT base address.

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The documentation for this struct was generated from the following file:

• machine/gdt.h