init_p.asm

自己编写的操作系统的源代码

        page    60,132
        title   PROTECTED MODE INITIALIZATION MOUDLE
;******************************************************************************
;******************************************************************************
;**                                                                          **
;**                                 init_p.asm                               **
;**                                                                          **
;**               Copyright (C) 2005-2006 Universe Corporation               **
;**                                                                          **
;**                            All Rights Reserved                           **
;**                                                                          **
;**                      Lanzhou University Of Tecnology                     ** 
;**                                                                          **
;**                              [phone]                              **
;**                                                                          **
;******************************************************************************
;******************************************************************************
;+ includes +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
        include asm\equates.inc
        include asm\macros.inc
        include asm\structs.inc
;+ code segment +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.486p
startup group   _init_p
_init_p segment word public use32 'CODE'
        assume  cs:startup
;------------------------------------------------------------------------------
        public  _INIT_P_STARTS
_INIT_P_STARTS  label   byte    ; marks start of module
;------------------------------------------------------------------------------
; re-initialize register
        mov     ax,DS_SEL
        mov     ds,ax
        mov     es,ax
        mov     fs,ax
        mov     gs,ax
        mov     ss,ax
        mov     esp,ESP_INIT_P

; initialize page directory
        mov     eax,00002007h
        mov     edi,PAGE_DIR_START
        mov     ecx,PAGE_TBLS_NR
next_page_dir:
        stosd
        add     eax,00001000h
        loop    next_page_dir
        
; initialize page table
        mov     eax,00000007h
        mov     di,PAGE_TBL_START
        mov     ecx,PAGE_TBLS_NR * 1024
next_page_tbl:
        stosd
        add     eax,00001000h
        loop    next_page_tbl
        
; make CR3 point to the page directory
        mov     eax,00001000h
        mov     cr3,eax
        
; enable paging
        mov     eax,cr0
        or      eax,8000000h
        mov     cr0,eax
        
        jmp     short $         ; system halt
;- data -----------------------------------------------------------------------
        org     INIT_P_SECS_NR * 512 - 2

        word    5a5ah
;------------------------------------------------------------------------------
        public  _INIT_P_ENDS
_INIT_P_ENDS    label   byte    ; marks end of module
;------------------------------------------------------------------------------
_init_p ends
;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
        end