rdconfig.asm

一个朋友写的操作系统源码

sseg segment stack

     db 128 dup (0)

sseg ends

dseg segment para public 'global'

     extrn parambuf:byte
     extrn paramnr:word
     extrn zonespace:byte

     extrn newline:byte

     configpath db 'config.txt',0  ; file name to be open

     inprom    db   13,10,13,10
               db   ' please input the full path for your kernel image:',13,10
               db   13,10,20h,'#','$'
     verion    db   13,10
               db   '                   stuix boot manager verion 1.0',13,10
               db   '                   ============================='
               db   13,10,13,10,'$'
     lodwin    db   ' 1. To load windows, press [w] key','$'
     lodstuix  db   ' 2. To load stuix, press [s] key','$'
     custlod   db   ' 3. To load a custom kernel press [m] key'
               db   13,10,13,10,' please enter your choice: ','$'

     canonbuf  db   21 dup (24h)
     clsbuf    db   21 dup (20h)
               db   '$'

dseg ends

cseg segment para public 'code'

     assume cs:cseg,ds:dseg,ss:sseg

     public rdconfig,chksynx,printmenu,pathinput,lodmbr,joinbuf

     extrn panic:near
     extrn printf:near


;/============================================================================
;
;                             rdconfig
;
;============================================================================/


     rdconfig proc near

     push ds  ; save caller's segment
     push es
     push bp  ; make stack frame
     mov bp,sp

     mov ax,3d00h  ; read only open file         
     mov dx,offset configpath
     int 21h
     jnc suc
     ; don't clear carry if error detected
     mov sp,bp
     pop bp  ; restore stack frame
     pop es
     pop ds
     ret     ; leave error code in ax

suc:
     mov bx,ax    ;we will read the config file
     xor ax,ax
     mov ah,3fh
     mov dx,offset parambuf
     mov cx,1024
     int 21h
     jnc suc1
     mov sp,bp
     pop bp
     pop es
     pop ds
     ret
suc1:
     mov [paramnr],ax   ; indicate how many byte we read from config file
     clc                ; guaratee no error

     ; the file handler is already set properly

     mov ah,3eh
     int 21h            ; close config file

     ; we don't care if this operating is successful

     mov sp,bp
     pop bp
     pop es
     pop ds
     ret

     rdconfig endp


;/============================================================================
;
;                             chksynx
;
;============================================================================/


     chksynx proc near

     push ds
     push es
     push bp
     mov bp,sp

     sub sp,4

     ; stack arranges like this

     ; [bp-2] : first '/' char position
     ; [bp-4] : first '$' char position

     ; try to find the '#', if '#' not present in our parameter
     ; buf, we will refuse to continue operating and panic

     cmp word ptr [paramnr],0    ; configuration file can't be NULL
     jne cnext1
     mov ax,105
     push ax
     call panic
cnext1:
     cld                 ; clear direction
     mov di,offset parambuf
     mov cx,[paramnr]
     mov al,35           ; '#'
     repnz scasb         ; find first '#' char
     jz found1
     mov ax,100          ; get appropriate error code
     push ax
     call panic
found1:

     ; '/' should be first encounted

     cld                 ; clear direction
     mov di,offset parambuf
     mov cx,[paramnr]
     mov al,47           ; '/'
     repnz scasb         ; find first '/' char
     jz found2
     mov ax,106
     push ax
     call panic
found2:
     mov [bp-2],di       ; save position of '/'
     cld                 ; clear direction
     mov di,offset parambuf
     mov cx,[paramnr]
     mov al,36           ; '$'
     repnz scasb         ; find first '$' char
     jz found3
     mov ax,106
     push ax
     call panic
found3:
     mov [bp-4],di
     cmp [bp-2],di       ; who is big?
     jb right
     mov ax,106
     push ax
     call panic
right:
     mov sp,bp
     pop bp
     pop es
     pop ds
     ret

     chksynx endp


;/============================================================================
;
;                             printmenu
;
;============================================================================/

     printmenu proc near

     push ds
     push es

     ; clear the screen and home cursor

     mov ch,0
     mov cl,0
     mov dh,24
     mov dl,79
     mov bh,07
     mov al,0
     mov ah,6
     int 10h             ; clear screen 
     mov bh,0
     mov dh,0
     mov dl,0
     mov ah,2
     int 10h             ; home cursor

     mov ax,offset verion
     push ax
     call printf
     pop cx

     mov ax,offset newline
     push ax
     call printf
     pop cx

     mov ax,offset newline
     push ax
     call printf
     pop cx

     mov ax,offset lodwin
     push ax
     call printf
     pop cx

     mov ax,offset newline
     push ax
     call printf
     pop cx

     mov ax,offset newline
     push ax
     call printf
     pop cx

     mov ax,offset lodstuix
     push ax
     call printf
     pop cx

     mov ax,offset newline
     push ax
     call printf
     pop cx

     mov ax,offset newline
     push ax
     call printf
     pop cx

     mov ax,offset custlod
     push ax
     call printf
     pop cx

     ; wait to accept user input, it only support
     ; w, s, m key, if other key is pressed, it
     ; will refuse to operate as if nothing hapens

waitkey:
     mov ah,0
     int 16h
     cmp al,77h    ; 'w'
     jne pmnext1
     mov ax,0
     pop es
     pop ds
     ret
pmnext1:
     cmp al,73h    ; 's'
     jne pmnext2
     mov ch,0
     mov cl,0
     mov dh,24
     mov dl,79
     mov bh,07
     mov al,0
     mov ah,6
     int 10h             ; clear screen 
     mov bh,0
     mov dh,0
     mov dl,0
     mov ah,2
     int 10h             ; home cursor

     mov ax,1
     pop es
     pop ds
     ret
pmnext2:
     cmp al,6dh          ; 'm'
     jne pmnext3
     mov ax,offset inprom
     push ax
     call printf
     pop cx

     mov ax,2
     pop es
     pop ds
     ret
pmnext3:
     jmp waitkey

     printmenu endp


;/============================================================================
;
;                             pathinput
;
;============================================================================/

     pathinput proc near

     push ds
     push es
     push bp
     mov bp,sp
     sub sp,8

     ; stack arranges like this

     ; [bp-2] : canonical buf pointer
     ; [bp-4] : canonical buf limiter
     ; [bp-6] : cursor line
     ; [bp-8] : cursor column

     ; initialize local variable

     mov word ptr [bp-2],offset canonbuf
     mov ax,offset canonbuf
     add ax,20
     mov [bp-4],ax

     ; save original cursor position

     mov ah,3
     mov bh,0
     int 10h
     mov [bp-6],dh
     mov [bp-8],dl

     ; create an input loop, until '$' is encounted
     ; it treat enter key as '$'

inputloop:

     ; first check the canonbuf pointer, if it
     ; execeed limiter, it's time to return

     mov ax,[bp-2]
     cmp ax,[bp-4]
     jb noful
     jmp endinput
noful:

     ; accept user input

     mov ah,0
     int 16h
     cmp al,1bh         ; 'esc'
     jne ipnext1
     mov word ptr [bp-2],offset canonbuf
     mov di,offset canonbuf
     mov al,24h         ; '$'
     mov cx,21
     cld
     repnz stosb

     ; restore cursor and clear the echo
     ; at last restore cursor again

     mov dh,[bp-6]
     mov dl,[bp-8]
     mov bh,0
     mov ah,2
     int 10h

     mov ax,offset clsbuf
     push ax
     call printf        ; line feed
     pop cx

     mov dh,[bp-6]
     mov dl,[bp-8]
     mov ah,2
     int 10h
     jmp inputloop
ipnext1:
     cmp al,8           ; back space
     jne ipnext2
     cmp word ptr [bp-2],offset canonbuf
     jne accept
     jmp inputloop
accept:

     dec word ptr [bp-2]    ; obsolete one char
     mov al,24h             ; feed with '$'
     mov di,[bp-2]
     cld
     stosb
     

     ; get current cursor position and obsolete one echo

     mov ah,3
     mov bh,0
     int 10h
     dec dl
     mov bh,0
     mov ah,2
     int 10h

     mov ah,3
     mov bh,0
     int 10h
     push dx

     mov ax,[bp-2]
     sub ax,offset canonbuf
     add ax,offset clsbuf
     push ax
     call printf
     pop cx

     pop dx
     mov ah,2
     mov bh,0
     int 10h

     jmp inputloop
ipnext2:
     cmp al,13            ; carridge return
     jne ipnext3
endinput:
     mov di,[bp-2]
     mov al,36            ; '$'
     cld
     stosb
     mov ax,[bp-2]
     sub ax,offset canonbuf
     inc ax

     ; return the number of char in canonbuf, including '$'

     mov sp,bp
     pop bp
     pop es
     pop ds
     ret
ipnext3:
     cmp al,36       ; '$'

     ; '$' don't need echo

     jne ipnext4
     jmp endinput
ipnext4:

     ; ordinary char process and echo

     mov di,[bp-2]
     cld
     stosb
     mov [bp-2],di
     mov bh,0
     mov ah,0eh
     int 10h
     jmp inputloop

     pathinput endp


;/============================================================================
;
;                             lodmbr
;
;============================================================================/


     lodmbr proc near

     push ds
     push es

     ; we just load mbr at 7c00h and execute it

     mov bx,offset zonespace
     mov dl,80h
     mov dh,0
     mov ch,0
     mov cl,1
     mov al,1
     mov ah,2
     int 13h
     mov ah,1
     int 13h
     cmp ah,0
     je hdok
     pop es
     pop ds                ; conversation method
     mov al,ah
     xor ah,ah
     push ax
     call panic
hdok:

     ; we don't believe the hard disk will fail
     ; if so, it must be a fatal error, it is
     ; not necessary to try any more

     pop es
     pop ds
     push ds
     push es
     mov ax,0
     mov es,ax
     mov di,7c00h
     mov si,offset zonespace
     mov cx,512
     cld
     repnz movsb
     mov ax,0
     mov ds,ax
     mov si,7c00h
     add si,200h-2
     lodsw
     cmp ax,0aa55h
     je execmbr
     pop es
     pop ds
     mov ax,11
     push ax
     call panic
execmbr:
     db 0eah
     dw 7c00h
     dw 0

     ; now stuix boot manager is obsoleting

     lodmbr endp


;/============================================================================
;
;                             joinbuf
;
;============================================================================/


     joinbuf proc near

     push ds
     push es
     push bp

     mov bp,sp
     sub sp,2

     ; stack arranges like this

     ; [bp-2] : number of char need to be concatenate

     mov ax,8[bp]
     mov [bp-2],ax

     mov si,offset canonbuf
     mov di,offset parambuf
     add di,11                ; skip string '/etc/fstab$'
     mov cx,[bp-2]
     cld
     repnz movsb
     mov al,23h               ; '#'
     stosb                    ; append at tail

     ; calulate the total effective character in parambuf

     mov si,offset parambuf
     sub di,si
     mov [paramnr],di         ; used by syntax check

     mov sp,bp
     pop bp
     pop es
     pop ds
     ret

     joinbuf endp


cseg ends

end