data segment;
num db 5
fnum dw ?
data ends
stack segment para stack 'stack';
db 100dup(?)
stack ends
code segment
assume cs:code,ds:data,es:data,ss:stack
main proc far
begin: push ds
mov ax,0
push ax
mov ax,data
mov ds,ax
mov es,ax
push cx
mov ah,0
mov al,num
call factor;
mov fnum,ax
pop cx
ret
main endp
factor proc
push ax
sub ax,1
jne next
pop ax
jmp exit
next:call factor;
pop cx
mul cl
exit:ret
factor endp
code ends
end begin
为了实现N!的计算,0<N<65535