汇编程序44：检测点13.1 (jmp near ptr 标号指令的中断例程)

 安装程序：
 assume cs:code
 //jmp near ptr 标号指令的替代实现,使用iret指令
 code segment
     start:
           mov ax,cs
           mov ds,ax
           mov si,offset sub1
           mov ax,0020h
           mov es,ax
           mov di,
           mov bx,offset sub2 - offset sub1
           cld
           rep movsb
           mov ax,
           mov es,ax
           mov word ptr es:[7ch*],200h
           mov word ptr es:[7ch*+],
           mov ax,4c00h
           int 21h
      sub1:
           push bp
           mov bp,sp
           cmp bx,-32768 //近转移最小值偏移
           jl s0 //有符号数小于则转移
           cmp bx,32767 //近转移最大值偏移
           jg s0 //有符号数大于则转移
           add [bp+],bx //加上两转的偏移即可得到转移目标地址
        s0:
           pop bp
           iret
      sub2:
           nop
 code ends

 end start

 测试程序：
 assume cs:code
 //将数据段的数据显示屏幕上
 data segment
     db 'conversation',
 data ends

 code segment
     start:
           mov ax,data
           mov ds,ax
           mov si,
           mov ax,0b800h
           mov es,ax
           mov di,*
         s:
           cmp byte ptr [si],
           je ok
           mov al,[si]
           mov es:[di],al
           inc si
           add di,
           mov bx,offset s - offset ok
           int 7ch //安装程序
        ok:
           mov ax,4c00h
           int 21h
 code ends

 end start