crt0.s

一个操作系统的源代码

;/** stub.s
; **
; ** Original Author: Kasper Verdich Lund
; ** Date: 10.26.99
; **
; ** Description:
; ** Kernel startup code 
; **
; ** This program is free software, you can redistribute it and/or
; ** modify it under the terms of the GNU General Public License
; ** as published by the Free Software Foundation; either version
; ** 2 of the License, or (at your option) any later version.
; **
; ** This program is distributed in the hope that it will be
; ** useful, but WITHOUT ANY WARRANTY; without even the implied
; ** warranty or MERCHANTABILITY or FITNESS FOR A PARTICULAR
; ** PURPOSE.  See the GNU General Public License for more
; ** details.
; **
; ** You should have received a copy of the GNU General Public
; ** License along with this program; if not, write to the
; ** Free Software Foundation, Inc., 59 Temple Place, Suite 330,
; ** Boston, MA 02111-1307 USA
; **
; *********************************************************Apostle OS**/

	SECTION	.text
	GLOBAL	_start
_start:	
	jmp	boot_entry

	ALIGN	4
	EXTERN	edata
	EXTERN	end
boot_hdr:
	dd	0x1BADB002
	dd	0x00010000
	dd	0-0x1BADB002-0x00010000
	dd	boot_hdr
	dd	_start
	dd	edata
	dd	end
	dd	boot_entry

	EXTERN	main
boot_entry:
	
	; ebx holds a pointer to
	; the multiboot info block
	
	mov	esp,boot_stack
	
	push	dword 0
	popf

; Clear the BSS

	mov	edi,edata
	mov	ecx,end
	sub	ecx,edi
	xor	eax,eax
	shr	ecx,2
	rep	stosd

	push	ebx		; save parameter for main
	
	call	main
	jmp	short $		; Hang


	SECTION	.bss
	ALIGNB	4
%IFDEF DEBUG
	RESB	4096
%ELSE
	RESB	1024
%ENDIF
boot_stack: