rdconfig.asm

来自「一个朋友写的操作系统源码」· 汇编 代码 · 共 67 行

sseg segment stack

     db 128 dup (0)

sseg ends

dseg segment para public 'global'

     extrn parambuf:byte
     extrn paramnr:word
     configpath db 'config.txt',0  ; file name to be open

dseg ends

cseg segment para public 'code'

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

     public 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
     mov sp,bp
     pop bp
     pop es
     pop ds
     ret

     rdconfig endp

cseg ends

end