DATA SEGMENT
     pkey   DB  0dh,0ah,"pleas input N end by ';' :$"
     over   DB  0AH,0DH,"overflow!",0dh,0ah,'$'
     result  DB  0dh,0ah,'result is:','$'
     DAT1  DB  8 DUP(0)
DATA ENDS

STACK SEGMENT
    SSTACK DB 100 DUP(0)
STACK ENDS 

CODE SEGMENT
     ASSUME CS:CODE,DS:DATA,SS:STACK 
     
STATE:  
    MOV AX,DATA
    MOV DS,AX
    LEA SI,DAT1     ;開辟緩沖區(qū)
    LEA DX,pkey
    MOV AH,9
    INT 21H         ;DOS功能調(diào)用，輸出字符串
    
LLP:MOV AH,1
    INT 21H         ;DOS功能調(diào)用，輸入N值
    SUB AL,2FH      
    INC DX          ;DX計(jì)數(shù)
    MOV [SI],AL     ;將輸入的數(shù)據(jù)存在SI緩沖區(qū)
    INC SI
    CMP AL,0CH      ;輸入為封號(hào)結(jié)束輸入
    JNZ LLP
    SUB SI,2
    CMP DX,02H      ;DX不為2表示輸入為兩位數(shù)
    JNZ LLLP 

LLP1:MOV CX,1
     MOV BL,2       ;賦初始值    
     JMP LP
LLLP:
     MOV DI,SI
     SUB DI,1          
     SUB [DI],1
     MOV AL,10
     MUL [DI]
     ADD [SI],AX     ;輸入是兩位數(shù)時(shí)十位乘10加個(gè)位
     SUB AH,AH
     JMP LLP1
     
LP: MOV BH,[SI]      ;把循環(huán)次數(shù)給BH
    MOV AL,BL
    INC BL
    MUL BL           ;BL(加1)和AL(原值)相乘給AX
    ADD CX,AX        ;AX和CX相加給CX，通過循環(huán)實(shí)現(xiàn)累加
    JO  OOF         ;如果溢出重新輸入
    CMP BH,BL        ;判斷是否達(dá)到N值
    JNZ LP 
    MOV AX,CX
    MOV CX,0AH
    MOV BX,0                 
              
    
LOP:MOV DX,0
    DIV CX         ;AX表示的32位數(shù)除以10，商放在AX,余數(shù)放在DX
    INC BX
    ADD DX,30H
    PUSH DX           ;將余數(shù)依次壓入棧
    CMP AX,0
    JNZ LOP           ;商不為0繼續(xù)除10
    LEA DX,result
    MOV AH,9
    INT 21H           ;DOS功能調(diào)用，輸出字符串  
    
OUTPUT:
     POP DX
     MOV AH,2
     INT 21H          ;DX中數(shù)據(jù)依次出棧并顯示
     DEC BX
     JNZ OUTPUT       ;出棧完成后停止
     JMP STATE            
     
OOF:LEA DX,over
    MOV AH,09H
    INT 21H           ;DOS功能調(diào)用，溢出顯示
    JMP STATE 
          
CODE ENDS

END STATE

DATA SEGMENT 
    pkey   DB  0AH,0DH,"Please Input N(1-8):",'$'  
    result DB  0AH,0DH,"the results is:",'$' 
    over   DB  0AH,0DH,"overflow!",0AH,0DH,'$'
DATA ENDS           

STACK SEGMENT
    SSTACK DB 100 DUP(0)
STACK ENDS          

CODE SEGMENT
    ASSUME CS:CODE,DS:DATA,SS:STACK
    
STATE: 
       MOV AX,DATA
       MOV DS,AX   ;數(shù)據(jù)段初始化

       LEA DX,pkey
       MOV AH,09H
       INT 21H       ;DOS功能調(diào)用，顯示字符串  
       
       MOV AH,1      
       INT 21H       ;DOS功能調(diào)用，輸入N 
       SUB AL,30H
       CMP AL,08H
       JA  OOF       ;輸入大于8溢出 
       
       XOR AH,AH   
       MOV BP,AX     ;賦循環(huán)計(jì)數(shù)值N給BP  
       
LP:    MOV BX,BP
       DEC BX
       JZ  LLP       ;階乘次數(shù)為BX,BX為0必須馬上跳轉(zhuǎn)
       MUL BX        ;AX中存放階乘結(jié)果(十六進(jìn)制轉(zhuǎn)十進(jìn)制用)
       DEC BP
       JNZ LP 

LLP:   MOV CX,0
       MOV BX,10
       
LLLP:  MOV DX,0     
       DIV BX        ;AX表示的32位數(shù)除以10，商放在AX,余數(shù)放在DX 
       ADD DX,30H    
       PUSH DX       ;將余數(shù)轉(zhuǎn)換為ASCII碼值并壓入棧
       INC CX
       CMP AX,0      ;商不為0就繼續(xù)除10
       JNZ LLLP 

       MOV AH,09H
       LEA DX,result 
       INT 21H       ;DOS功能調(diào)用，輸出字符串
       
LOP:   POP DX           
       MOV AH,2                                     
       INT 21H       ;DX各位出棧并顯示
       LOOP LOP     
       JMP STATE   

OOF:   LEA DX,over
       MOV AH,09H
       INT 21H      ;DOS功能調(diào)用，溢出顯示
       JMP STATE 
   
CODE ENDS
     END STATE