硬盘.txt

会变语言实现的一些程序

    当我学习从DOS转向WINDOWS MASM32 时，曾在一些BBS上，提问过如何在Win下读写硬盘扇区，
也看了其他人提出的类似问题，但不知是出于何种原因，高手们都是闪烁其词，或让你去写VXD、
或提示你int_31的用法，就是不愿意直面问题。
    下面是我在DOS下摸索出而在Win下实现的例子。没有复杂的过程，现将此贴出，不知妥否。
    
;******************************
; 03-3-30 23:17
; 实验：直接读写硬盘
; 例一：在Ring0环境下，读出硬盘的主引导扇区    
;
; 例二：在Ring0环境下，向硬盘写入数据
;******************************

.586P
.MODEL FLAT, STDCALL
option casemap:none
include \masm32\include\windows.inc
include \masm32\include\user32.inc
include \masm32\include\kernel32.inc

includelib \masm32\lib\user32.lib
includelib \masm32\lib\kernel32.lib



.data

GDTR        df 0            ; This will receive the contents of the IDTR
                            ; register

CallPtr     dd 00h          ; As we're using the first descriptor (8) and
            dw 0Fh          ; its located in the LDT and the privilege level
                            ; is 3, our selector will be 000Fh.
                            ; That is because the low-order two bits of the
                            ; selector are the privilege level, and the 3rd
                            ; bit is set if the selector is in the LDT.

OurGate     dw 0            ; Offset low-order word
            dw 028h         ; Segment selector
            dw 0EC00h       ;
            dw 0            ; Offset high-order word

;----------------------------------------------------------------            
param   db 0,1,0,0,0                
        db 0e0h
        db 0c4h                     

   ASCII_      db     '0123456789ABCDEF'
   byte_       dd     200h
   Caption      db     'Windows 9x绝对磁盘读写，第0扇区',0



.data?
         Buffer        db    200h dup(?)
   ShowText   db    200h*3 dup (?)
;----------------------------------------------------------------            
.code

Start:

      mov      eax, offset Ring0Proc
      mov      [OurGate], ax              ; Put the offset words
      shr      eax, 16                    ; into our descriptor
      mov      [OurGate+6], ax

      xor      eax, eax
      sgdt     fword ptr GDTR
      mov      ebx, dword ptr [GDTR+2]    ; load GDT Base Address
      sldt     ax
      add      ebx, eax                   ; Address of the LDT descriptor in ebx
      mov      al, [ebx+4]                ; Load the base address
      mov      ah, [ebx+7]                ; of the LDT itself into
      shl      eax, 16                    ; eax, refer to your pmode
      mov      ax, [ebx+2]                ; manual for details

      add      eax, 8                     ; Skip NULL Descriptor
      mov      edi, eax
      mov      esi, offset OurGate
      movsd                               ; Move our custom callgate
      movsd                               ; into the LDT

      call     fword ptr [CallPtr]        ; Execute the Ring0 Procedure

      xor      eax, eax                   ; Clean up the LDT
      sub      edi, 8                     ; edi之值跟随在先前的 movsd 指令后。
      stosd
      stosd
      nop

;**********************************************
         call ShowBuffer
         invoke MessageBoxA,NULL,offset ShowText,offset Caption,MB_OK

      INVOKE     ExitProcess,NULL
;**********************************************


ShowBuffer proc                  

            cld                             
           lea  esi, Buffer            
           lea  edi, ShowText          
           mov  ebx,offset ASCII_        
           xor  edx,edx
           xor  ecx,ecx
   compute:
           xor  eax,eax
            cmp  edx,byte_
            jnc   end_
            lodsb
           push eax
           shr  eax,4           
           mov  al,[ebx+eax]
            stosb
           pop  eax
           and  eax,0fH         
           mov  al,[ebx+eax]
            mov  ah,' '                   
            stosw
           inc  ecx
           cmp  ecx,16               
           jnz  compute
           add  edx,ecx
           xor  ecx,ecx
           mov  byte ptr[edi-1],0dh
           jmp  compute
   end_:
             ret
             
ShowBuffer endp


;**********************************************

Ring0Proc PROC

;------------------------------------------------------

         pushad   
         mov al,[param+5]               
         mov dx,1f6h
         out dx,al
         call delay              
         mov ecx,6
         lea esi,param
         mov dx,1f1h             
outp:   lodsb                    
         out dx,al               
         inc dx                  
         loop outp               
         nop                     
         call delay
         lodsb
         out dx,al               
test_:   in al,dx
         cmp al,58h
         jnz test_
         xor eax,eax
         mov ecx,80h
         mov al,[param+1]
         mul cx
         mov ecx,eax
         lea edi,Buffer          
         mov dx,1f0h
         rep insd                
         nop
         popad
         xor eax,eax
         retf
delay:
         mov ecx,1000h
         mov dx,1f7h
n1:       in  al,dx
         cmp al,50h                 
         jz  n2
         loop n1
         mov  eax,1
n2:       ret

Ring0Proc ENDP


;**********************************************

            end Start