子程序递归的问题

2010-09-09 09:28:01 109 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

如下代码：是杨继文《80X86汇编语言程序设计教程》中关于子程序递归的代码。我觉得有问题，我原封不动抄上来，请大家指出哪错啦？



fact	proc

	push dx

	mov dx,ax

	cmp ax,0

	jz done

	dec ax

	call fact

	mul dx

	pop dx

	ret

done:	mov ax,1

	pop dx

	ret

fact	endp

...全文

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masmaster 2010-09-10

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[Quote=引用 2 楼 suchx 的回复:]
This program looks strange, you can write your own fact program.
Assembly code

.MODEL SMALL
.STACK 1024H
CR=0DH
LF=0AH
.DATA
INMES DB 'INPUT N : ','$'
CHRERR DB CR,LF,'0..9 EXPECTED.',CR,LF……
[/Quote]

thanks

suchx 2010-09-10

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This program looks strange, you can write your own fact program.



.MODEL SMALL

.STACK 1024H

CR=0DH

LF=0AH

.DATA

INMES  DB 'INPUT N : ','$'

CHRERR DB CR,LF,'0..9 EXPECTED.',CR,LF,'$'

RNGERR DB CR,LF,'RANGE CHECK ERROR .','$'

OUTMES DB CR,LF,'FACT= ','$'

HLTMES DB CR,LF,'PRESS ANY KEY TO HALT .','$'

BUFSIZE=6

BUF    DB BUFSIZE

       DB 0

       DB BUFSIZE DUP(0)

     N DW 0

     Y DW 0

BASE   DW 10

.CODE

_MAIN PROC NEAR

START:NOP

      MOV AX,@DATA

      MOV DS,AX

      MOV ES,AX

      CALL READ

      MOV CX,N

      CALL FACT

      MOV Y,AX

      CALL WRITE

      MOV AX,4C00H

      INT 21H

_MAIN ENDP

READ PROC NEAR

  RE1:LEA DX,INMES

      CALL DISPMES

      LEA DX,BUF

      MOV AH,0AH

      INT 21H

      CALL ATOD

      JC RE1

      MOV N,AX

      RET

READ ENDP

FACT PROC NEAR

      PUSH CX

      TEST CX,CX

      JZ F1

      DEC CX

      TEST CX,CX

      JZ F1

      CALL FACT

      POP CX

      MUL CX

      TEST DX,DX

      JZ F2

      LEA DX,RNGERR

      CALL DISPMES

      CALL HALT

      JMP SHORT F2

   F1:POP CX

      MOV AX,1

   F2:RET

FACT ENDP

WRITE PROC NEAR

       LEA DX,OUTMES

       CALL DISPMES

       MOV AX,Y

       CALL DTOA

       LEA DX,BUF[2]

       CALL DISPMES

       RET

WRITE ENDP

ATOD   PROC NEAR

       PUSH SI

       XOR AX,AX

       XOR DX,DX

       XOR BX,BX

       XOR CH,CH

       MOV CL,BUF[1]

       LEA SI,BUF[2]

   AT1:MUL BASE

       TEST DX,DX

       JZ AT2

       LEA DX,RNGERR

       CALL DISPMES

       JMP SHORT AT9

   AT2:MOV BL,[SI]

       CMP BL,'0'

       JB AT3

       CMP BL,'9'

       JA AT3

       JMP SHORT AT4

   AT3:LEA DX,CHRERR

       CALL DISPMES

       JMP SHORT AT9

   AT4:SUB BL,'0'

       ADD AX,BX

       JNO AT5

       LEA DX,RNGERR

       CALL DISPMES

       JMP SHORT AT9

   AT5:INC SI

       LOOP AT1

       CLC

       JMP SHORT AT8

   AT9:STC

   AT8:POP SI

       RET

ATOD   ENDP

DTOA   PROC NEAR

       PUSH SI

       PUSH DI

       XOR CX,CX

       LEA DI,BUF[2+BUFSIZE-1]

       MOV WORD PTR [DI],'$'

       DEC DI

   DT1:XOR DX,DX

       DIV BASE

       ADD DL,'0'

       MOV [DI],DL

       DEC DI

       INC CX

       TEST AX,AX

       JNZ DT1

       MOV SI,DI

       INC SI

       LEA DI,BUF[2]

       CLD

       REP MOVSB

       MOV BYTE PTR [DI],'$'

       POP DI

       POP SI

       RET

DTOA   ENDP

DISPMES PROC NEAR

       PUSH AX

       MOV AH,9

       INT 21H

       POP AX

       RET

DISPMES ENDP

HALT  PROC NEAR

       LEA DX,HLTMES

       CALL DISPMES

       MOV AH,1

       INT 21H

       MOV AX,4C00H

       INT 21H

HALT  ENDP

END START

masmaster 2010-09-09

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这本书给我的感觉，错误确实不少！！！