求大神帮忙解一个简单汇编程序（数制之间的转换）

求大神回复

CODE  SEGMENT
              ASSUME    CS:CODE
 
        BUFF  DB        3,?,3 DUP(?)
        ERRR  DB        13,10,'error $'
        LFCR  DB        13,10,'$'
 
      START:  PUSH      CS
              POP       DS
              PUSH      CS
              POP       ES
         @0:
              MOV       AH,10
              LEA       DX,BUFF
              INT       21H
 
              LEA       SI,BUFF
              MOV       CL,[SI+1]
              MOV       CH,0
              CLD
              ADD       SI,2
              MOV       BL,0
         @1:
              LODSB
              CMP       AL,'0'
              JB        @10
              CMP       AL,'9'
              JBE       @9
              CMP       AL,'A'
              JB        @10
              CMP       AL,'F'
              JBE       @8
              CMP       AL,'a'
              JB        @10
              CMP       AL,'f'
              JBE       @7
              JMP       @10
         @7:
              SUB       AL,'a'
              ADD       AL,10
              JMP       @11
         @8:
              SUB       AL,'A'
              ADD       AL,10
              JMP       @11
         @9:
              SUB       AL,'0'
              JMP       @11
        @10:
              LEA       DX,ERRR
              MOV       AH,9
              INT       21H
              JMP       @0
        @11:
              ROL       BL,1
              ROL       BL,1
              ROL       BL,1
              ROL       BL,1
              ADD       BL,AL
              LOOP      @1
              MOV       AL,BL
              MOV       AH,0
              PUSH      AX
              PUSH      AX
               
              MOV       AH,9
              LEA       DX,LFCR
              INT       21H
 
              POP       AX
              CALL      DSPAX10
              POP       AX
              CALL      DSPAX2
               
              MOV       AH,4CH
              INT       21H
;================================   
      DSPAX2  PROC      NEAR
              PUSH      AX
              PUSH      BX
              PUSH      CX
              PUSH      DX
              PUSHF
              XOR       CX,CX
              MOV       BX,2
  @DSPAX2_1:
              XOR       DX,DX
              DIV       BX
              INC       CX
              OR        DX,30H
              PUSH      DX
              CMP       AX,0
              JNE       @DSPAX2_1
              MOV       AH,2
 @DISPAX2_2:
              POP       DX
              CMP       DL,3AH
              JB        @DISPAX2_3
              ADD       DL,7
 @DISPAX2_3:
              INT       21H
              LOOP      @DISPAX2_2
              MOV       DL,32
              INT       21H
              POPF
              POP       DX
              POP       CX
              POP       BX
              POP       AX
              RET
      DSPAX2  ENDP
;================================   
     DSPAX10  PROC      NEAR
              PUSH      AX
              PUSH      BX
              PUSH      CX
              PUSH      DX
              PUSHF
              XOR       CX,CX
              MOV       BX,10
 @DSPAX10_1:
              XOR       DX,DX
              DIV       BX
              INC       CX
              OR        DX,30H
              PUSH      DX
              CMP       AX,0
              JNE       @DSPAX10_1
              MOV       AH,2
            @DISPAX10_2:
              POP       DX
              CMP       DL,3AH
              JB        @DISPAX10_3
              ADD       DL,7
            @DISPAX10_3:
              INT       21H
              LOOP      @DISPAX10_2
              MOV       DL,32
              INT       21H
              POPF
              POP       DX
              POP       CX
              POP       BX
              POP       AX
              RET
     DSPAX10  ENDP
;================================              
        CODE  ENDS
              END       START





注释：要求是“以两个空格作为间隔”该程序是一个空格；
最后一句，“在下一行显示该十六进制数交换后的值”，该程序没有编辑。
要求举例：
输入：3A
输出：A3


速回谢谢！！！

感谢大神，我肯定好好努力