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;********************************************************************************************************************************
;*																																*
;*	File: GDT.inc																												*
;*																																*
;*	This file defines the structures, constants, and macros for the Global Descriptor Table, or <GDT>, and its selectors.		*
;*																																*
;*	See Also:																													*
;*		- <Boot.asm>																											*
;*																																*
;*	Authors:																													*
;*		- Neil G. Dickson																										*
;*																																*
;********************************************************************************************************************************

;********************************************************************************************************************************
;*																																*
;*	Constants: GDT Selector Constants																							*
;*																																*
;*	These constants define segment selectors into the <GDT>.																	*
;*																																*
;*	SELECTOR_CORE_CODE				- <Core> code segment selector																*
;*	SELECTOR_CORE_DATA				- <Core> data segment selector																*
;*	SELECTOR_CORE_CALL_GATE			- <CoreCallGate> selector																	*
;*	SELECTOR_THREAD_SCHEDULER_TSS	- <ThreadSchedulerTSS> selector																*
;*	SELECTOR_USER_CODE				- Code segment selector for all applications												*
;*	SELECTOR_USER_DATA				- Data segment selector for all applications												*
;*	SELECTOR_BOOT_TSS				- <Boot> TSS selector (until <Boot> is unloaded)											*
;*																																*
;*	SZ_STORED_GDT					- Size of the initial <GDT>																	*
;*																																*
;********************************************************************************************************************************
SELECTOR_CORE_CODE				equ	08h
SELECTOR_CORE_DATA				equ	10h
SELECTOR_CORE_CALL_GATE			equ	18h
SELECTOR_THREAD_SCHEDULER_TSS	equ	20h
SELECTOR_USER_CODE				equ	28h
SELECTOR_USER_DATA				equ	30h
SZ_STORED_GDT					equ	38h

;********************************************************************************************************************************
;*																																*
;*	Macro: TSS_DESC																												*
;*																																*
;*	Define a qword of data containing a TSS descriptor.																			*
;*																																*
;*	Parameters:																													*
;*		address		- the address of the TSS																					*
;*		privilege	- the privilege level of the descriptor																		*
;*																																*
;********************************************************************************************************************************
TSS_DESC	MACRO	address,privilege
	dw	sizeof TSS32
	dw	lowword address
	db	(highword address) and 0FFh
	db	DESC_S_TSS_AVL_32 or DESC_PRESENT_BIT or privilege
	db	0
	db	high address
ENDM

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