test.asm

清华大学计算机系汇编语言课程

data segment


mess1       db 'Please input the  mark!',0ah,0dh,'$'
mess2       db 'The average mark is:',0ah,0dh,'$'
buf1         db 60
db ?
db 60 dup(?)
buf2         db 30  dup(?)
buf3         db 2 dup(0),'$'
data ends
code segment
assume cs:code,ds:data
start:  mov ax,data
mov ds,ax
lea dx,mess1
mov ah,9
int 21h
call input

	  lea      si,buf1
	  mov      cx,[si+1]
	  and      cx,0fh
	  shr       cx,1
	  dec       cx
	  lea       di, buf2
	  mov       al,[di]
	  L2:     inc        di

	  add       ax,[di]

	  loop       L2
	  div        cl
	  call        output
	  ;=====================================================================================
	  input  proc                               ;该子程序把输入的成绩转换成一字节压缩BCD码存放
	  pushf
	  push  ax
	  push  cx
	  push  bx
	  push  dx

	      push  di
	      mov     dx,offset buf1
	      mov     ah,0ah
	      int     21h

	  lea      si,buf1
	  mov      dl,0
	  mov      bl,0

	  mov      cx,[si+1]
	  and      cx,0fh
	  shr       cx,1
	  lea       di,buf2
	  L1:     mov      dl,[si+2]               ;把输入的第一个数字给dl
	  sub      dl,30h
	  shl      dl,1
	  shl      dl,1
	  shl      dl,1
	  shl      dl,1
	  mov      bl,[si+3]               ;把输入的第二个数字给bl
	  sub       bl,30h
	  add       dl,bl

	  mov       [di],dl
	  inc       di
	  add       si,2
	  loop       L1
	  pop        di

	  pop        dx
	  pop        bx
	  pop     cx
	  pop     ax
	  popf
	  ret
	  input endp
	  ;===============================================================================
	  output proc                                         ;该子程序把BCD码转换成asc码



	  push      bx
	  push      cx
	  push      dx






          push      si
	  push      di
	  mov       cl,4
	  lea       si,buf3
	  mov       ah,al

          mov       bl,ah

	  shr        bl,cl
	  add       bl,30h
	  mov       [si],bl
	  and       ah,0fh
	  add       ah,30h
	  mov       [si+1],ah
	  lea dx,mess2
	  mov ah,9
	  int 21h
	  mov  dx,offset buf3
	  mov  ah,9
	  int   21h
	  pop       di
	  pop       si
	  pop       dx
	  pop       cx
	  pop       bx


	  ret
	  output endp
	  code ends
	  end start