73.asm

本书为清华大学第二版汇编语言的课后题详解

;7_3.asm

(1)
absdif  p1,p2,distance
宏展开:
1       push ax
2       mov  ax,p1
2       sub  ax,p2
1       cmp  ax,0
1       jge  ??0000
1       neg  ax
1??0000:mov  distance,ax
1       pop  ax

(2)
absdif  [bx],[si],x[di],cx
宏展开:
1       push ax
2       mov  ax,[bx]
2       sub  ax,[si]
1       cmp  ax,0
1       jge  ??0000
1       neg  ax
1??0000:mov  x[di],ax
1       pop  ax

(3)
absdif  [bx][si],x[bx][si],240h
宏展开:
1       push ax
2       mov  ax,[bx][si]
2       sub  ax,x[bx][si]
1       cmp  ax,0
1       jge  ??0000
1       neg  ax
1??0000:mov  240h,ax
1       pop  ax

(4)
absdif  ax,ax,ax
宏展开:
1       push ax
2       mov  ax,ax
2       sub  ax,ax
1       cmp  ax,0
1       jge  ??0000
1       neg  ax
1??0000:mov  ax,ax
1       pop  ax
    该调用是无效的,因为宏展开后得到的语句不是有效的.