assume cs:code
code segment
start: mov ax,60 ;测试数据
call showsin
mov ax,4c00h
int 21h
showsin: jmp short show
table dw ag0,ag30,ag60,ag90,ag120,ag150,ag180
ag0 db '0',0
ag30 db '0.5',0
ag60 db '0.866',0
ag90 db '1',0
ag120 db '0.866',0
ag150 db '0.5',0
ag180 db '0',0
show: push bx
push es
push si
mov bx,0b800h
mov es,bx
cmp ax,0
jb showret
cmp ax,180
ja showret
;mov ah,0 ;???疑问在这里???
mov bl,30
div bl
mov bl,al
mov bh,0
add bx,bx
mov bx,table[bx]
mov si,160*12+40*2
shows: mov ah,cs:[bx]
cmp ah,0
je showret
mov es:[si],ah
inc bx
add si,2
jmp short shows
showret: pop si
pop es
pop bx
ret
code ends
end start
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疑问：为什么要加这条指令，不知道意义何在，我将之注释掉，对结果并无影响 |
