aexp4.asm

微机接口技术的入门必备试验代码 试验平台msdi

 ;*-------------------------------------------------------*
 ;*  Aexp4.asm(分支程序设计实验)                           *
 ;*  Copyright (c) 2002 by HUST                           *
 ;*  程序调试：在EXIT:MOV AH,4CH处设置断点，利用Add Watch   *
 ;*           命令查看A中的内容是否正确                     *
 ;*-------------------------------------------------------*

STACK  SEGMENT STACK
       DB 200 DUP(0)
STACK  ENDS
DATA   SEGMENT
 X     DB -2
 Y     DB 8
 A     DB ?
DATA   ENDS
CODE  SEGMENT
      ASSUME CS:CODE,DS:DATA,SS:STACK
START:
      MOV  AX,DATA
      MOV  DS,AX
      
      CMP  X,0     ;x与0进行比较
      JS   L1      ;x<0转L1
      CMP  Y,0    
      JL   L2      ;y<0转L2
      MOV  A,1     ;1送A
      JMP EXIT
L1:   CMP  Y,0
      JGE  L2      ;y>=0转L2
      MOV  A,-1    ;x<0,y<0时，-1送A
      JMP EXIT
L2:   MOV  A,0     ;x与y异号时，0送A         
EXIT: MOV AH,4CH
      INT 21H        
CODE  ENDS
END START