js.asm

汇编源代码

         B_P  EQU       BYTE PTR
         W_P  EQU       WORD PTR
         D_P  EQU       DWORD PTR
        CODE  SEGMENT
              ASSUME    CS:CODE,DS:CODE
              ORG       100H
;主程序开始
    NEWSTAR:
              JMP       STAR
              EVEN
        NUM1  DW        0,0
        NUM2  DW        0,0
        NUM3  DW        0,0
              JGV4      DW 0,0
         YSF  LABEL     WORD
        YSF1  DB        0
        YSF2  DB        0
              JUV       DB 0
          UV  DB        0
;使DS:SI指向第一有效字符
       OVERS  LABEL     NEAR
              CLD
              PUSH      AX
     OVERS1:
              LODSB
              CMP       AL,' '
              JZ        OVERS1
              CMP       AL,9
              JZ        OVERS1
              DEC       SI
              CMP       AL,13
              POP       AX
              RET
;输出一个制表符
         TAB  LABEL     NEAR
              MOV       AL,9
              JMP       SHORT DISP
;输出一个回车换行符
        CRLF  LABEL     NEAR
              MOV       AL,13
              CALL      DISP
              MOV       AL,10
;显示一个字符
        DISP  LABEL     NEAR
              PUSH      AX
              PUSH      DX
              MOV       AH,2
              MOV       DL,AL
              INT       21H
              POP       DX
              POP       AX
              RET
;检查是否为运算符
       ISYSF  LABEL     NEAR
              CLD
              LODSB
              CALL      ISJJ
              JZ        ISYSF1
              CALL      ISII
              JZ        ISYSF1
              DEC       SI
     ISYSF1:
              RET
;检查是否是加减运算
        ISJJ  LABEL     NEAR
              CMP       AL,'+'
              JZ        ISYSF1
              CMP       AL,'-'
              RET
;检查是否为乘除运算
        ISII  LABEL     NEAR
              CMP       AL,'*'
              JZ        ISYSF1
              CMP       AL,'/'
              JZ        ISYSF1
              CMP       AL,'\'
              RET
;数据输出
;CX=10 十进制
;CX=16 十六进制
        DOUT  LABEL     NEAR
              PUSH      AX
              PUSH      BX
              PUSH      DX
              PUSH      BP
              XOR       BP,BP
      DOUT1:
              INC       BP
              PUSH      AX
              MOV       AX,DX
              XOR       DX,DX
              DIV       CX
              MOV       BX,AX
              POP       AX
              DIV       CX
              PUSH      DX
              MOV       DX,BX
              OR        BX,AX
              JNZ       DOUT1
      DOUT2:
              POP       AX
              ADD       AL,'0'
              CMP       AL,'9'
              JBE       DOUT3
              ADD       AL,'A'-'9'-1
      DOUT3:
              CALL      DISP
              DEC       BP
              JNZ       DOUT2
              POP       BP
              POP       DX
              POP       BX
              POP       AX
              RET
;输入数据在DX:AX中返回
;CX=0 数据为10进制
;CX#0 数据为16进制
        DATE  LABEL     NEAR
              PUSH      BX
              PUSH      BP
              PUSH      DI
              XOR       AX,AX
              XOR       DX,DX
      DATE1:
              MOV       DI,AX
              LODSB
              CMP       AL,'0'
              JB        DATE7
              CMP       AL,'9'
              JA        DATE6
      DATE2:
              AND       AX,0FH
              SHL       DI,1
              RCL       DX,1
              MOV       BX,DI
              MOV       BP,DX
              SHL       DI,1
              RCL       DX,1
              SHL       DI,1
              RCL       DX,1
              JCXZ      DATE3
              SHL       DI,1
              RCL       DX,1
              JMP       SHORT DATE4
      DATE3:
              ADD       DI,BX
              ADC       DX,BP
      DATE4:
              ADD       AX,DI
              ADC       DX,0
              JMP       DATE1
      DATE5:
              ADD       AL,9
              JMP       DATE2
      DATE6:
              JCXZ      DATE7
              CMP       AL,'A'
              JB        DATE7
              CMP       AL,'F'
              JBE       DATE5
              CMP       AL,'a'
              JB        DATE7
              CMP       AL,'f'
              JBE       DATE5
      DATE7:
              MOV       AX,DI
              DEC       SI
              OR        DI,DX
              POP       DI
              POP       BP
              POP       BX
              RET
;数据1与数据2根据YSF1进行加减运算
              JSJJ      LABEL NEAR
              MOV       AX,NUM2
              MOV       DX,NUM2+2
              CMP       YSF1,'+'
              JZ        JSJJ1
              SUB       NUM1,AX
              SBB       NUM1+2,DX
              JMP       SHORT JSJJ2
              JSJJ1:
              ADD       NUM1,AX
              ADC       NUM1+2,DX
              JSJJ2:
              RET
;数据1与数据2根据YSF1进行乘除运算
              JSII1     LABEL NEAR
              MOV       BX,OFFSET NUM1
              JMP       SHORT JSII2_1
;数据2与数据3根据YSF2进行乘除运算
              JSII2     LABEL NEAR
              MOV       BX,OFFSET NUM2
              JSII2_1:
              DB        66H
              MOV       AX,[BX]
              DB        66H
              MOV       CX,[BX+4]
              CMP       YSF2,'*'
              JNZ       JSII2_2
              DB        66H
              IMUL      CX
              JMP       SHORT JSII2_3
              JSII2_2:
              DB        66H
              CWD
              DB        66H
              IDIV      CX
              CMP       YSF2,'/'
              JZ        JSII2_3
              DB        66H
              XCHG      DX,AX
              JSII2_3:
              DB        66H
              MOV       [BX],AX
              RET
;显示结果
        XUJG  LABEL     NEAR
              MOV       AX,JGV4
              MOV       DX,JGV4+2
              MOV       CX,10
              CMP       UV,10
              JZ        XUJG0
              MOV       CX,16
      XUJG0:
              TEST      DX,8000H
              JZ        XUJG1
              CMP       UV,10
              JZ        XUJG2
              CALL      DOUT
      XUJG2:
              NOT       AX
              NOT       DX
              ADD       AX,1
              ADC       DX,0
              PUSH      AX
              CMP       UV,10
              JZ        XUJG3
              MOV       AL,' '
              CALL      DISP
              MOV       AL,'('
              CALL      DISP
      XUJG3:
              MOV       AL,'-'
              CALL      DISP
              POP       AX
              CMP       UV,10
              JZ        XUJG1
              CALL      DOUT
              MOV       AL,')'
              CALL      DISP
              RET
      XUJG1:
              CALL      DOUT
              RET
;计算结果放入DX:AX中
              JSJG      LABEL NEAR
              CALL      JSJJ
              MOV       AX,NUM1
              MOV       DX,NUM1+2
              RET
;从DS:SI处取一个数据
     LOADATE  LABEL     NEAR
              LODSB
              CMP       AL,'('
              JZ        LOADATE1
              DEC       SI
              PUSH      CX
              XOR       CX,CX
              CMP       UV,10
              JZ        LOADATE0
              INC       CX          ;取16进制数
   LOADATE0:
              CALL      DATE        ;取数据放入DX:AX中
              POP       CX
              RET
   LOADATE1:
              PUSH      NUM1        ;保存数据1数据2及运算符
              PUSH      NUM1+2
              PUSH      NUM2
              PUSH      NUM2+2
              PUSH      YSF
              INC       JUV
              MOV       JGV4,0      ;结果值清零
              MOV       JGV4+2,0
;进行四则运算
        SZYS  LABEL     NEAR
              CALL      ISYSF       ;首字符是运算符？
              JZ        SZYS2
              CALL      LOADATE     ;不是，取数并保存
              MOV       NUM1,AX
              MOV       NUM1+2,DX
      SZYS1:
              XOR       AX,AX       ;数据2清零
              MOV       NUM2,AX
              MOV       NUM2+2,AX
              CALL      ISYSF       ;下个是运算符？
              JZ        SZYS3
              JNZ       SZYS6
      SZYS2:
              PUSH      AX
              MOV       AX,JGV4     ;将结果作为数据1
              MOV       NUM1,AX
              MOV       AX,JGV4+2
              MOV       NUM1+2,AX
              POP       AX
      SZYS3:
              MOV       YSF1,AL
              MOV       YSF2,AL
              CALL      ISJJ        ;是加减运算转
              JZ        SZYS4
              CALL      LOADATE     ;取数据2
              MOV       NUM2,AX
              MOV       NUM2+2,DX
              CALL      JSII1       ;数据1与数据2根据YSF1进行乘除运算
              JMP       SZYS1       ;    结果保存在数据1中
      SZYS4:
              CALL      LOADATE     ;取数据2并保存
              MOV       NUM2,AX
              MOV       NUM2+2,DX
    SZYS4_1:
              CALL      ISYSF
              JNZ       SZYS6
              CALL      ISJJ        ;运算符2是加减运算？
              JNZ       SZYS5       ;不是转
              PUSH      AX
              CALL      JSJJ        ;数据1与数据2根据YSF1进行加减运算
              POP       AX          ;    结果保存在数据1中
              MOV       YSF1,AL     ;保存新的运算符
              JMP       SZYS4
      SZYS5:
              MOV       YSF2,AL     ;保存运算符2
              CALL      LOADATE     ;取数据3
              MOV       NUM3,AX
              MOV       NUM3+2,DX
              CALL      JSII2       ;数据2与数据3根据YSF2进行乘除运算
              JMP       SZYS4_1     ;    结果保存在数据2中
      SZYS6:
              MOV       CL,AL
              CMP       AL,13
              JNZ       SZYS9
      SZYS7:
              CALL      JSJG
              CMP       JUV,0
              JZ        SZYS8
              DEC       JUV
              POP       YSF
              POP       NUM2+2
              POP       NUM2
              POP       NUM1+2
              POP       NUM1
              RET
      SZYS8:
              CMP       CL,')'
              JZ        SZYS10
              MOV       JGV4,AX
              MOV       JGV4+2,DX
              JNZ       SZYS12
      SZYS9:
              CMP       AL,')'
              JNZ       SZYS11
              INC       SI
              JMP       SZYS7
     SZYS10:
              MOV       NUM1,AX
              MOV       NUM1+2,DX
              JMP       SZYS1
     SZYS11:
              STC
              RET
     SZYS12:
              CLC
              RET
;数制处理
        UVIL  LABEL     NEAR
              PUSH      SI
      UVIL1:
              LODSB
              CMP       AL,' '
              JZ        UVIL2
              CMP       AL,9
              JZ        UVIL2
              CMP       AL,13
              JZ        UVIL4
              JNZ       UVIL1
      UVIL2:
              MOV       BX,SI
              CALL      OVERS
              JZ        UVIL3
              LODSW
              CALL      OVERS
              POP       SI
              JNZ       SZYS11
              CMP       AX,'01'
              JNZ       SZYS11
              PUSH      SI
              MOV       UV,10
      UVIL3:
              MOV       AL,13
              MOV       [BX-1],AL
      UVIL4:
              POP       SI
              CLC
              RET
;预置结果
        YVJG  LABEL     NEAR
              MOV       AH,52H
              INT       21H
              MOV       AX,ES:[BX-2]
              MOV       DS,AX
              MOV       AX,DS:[0CH]
              MOV       CS:JGV4,AX
              MOV       AX,DS:[0EH]
              MOV       CS:JGV4+2,AX
              PUSH      CS
              POP       DS
              PUSH      CS
              POP       ES
              RET
;保存结果
        BCJG  LABEL     NEAR
              MOV       AH,52H
              INT       21H
              MOV       AX,ES:[BX-2]
              MOV       DS,AX
              MOV       AX,CS:JGV4
              MOV       DS:[0CH],AX
              MOV       AX,CS:JGV4+2
              MOV       DS:[0EH],AX
              PUSH      CS
              POP       DS
              PUSH      CS
              POP       ES
              RET
       STAR:
              MOV       SI,81H
              CLD
              CALL      OVERS
              JNZ       STAR1
      STAR0:
              MOV       DX,OFFSET MESS1
              JMP       STAR4
      STAR1:
              CALL      YVJG
              CALL      UVIL
              JB        STAR0
              MOV       SAVESP,SP
              CALL      SZYS
              MOV       SP,SAVESP
              MOV       DX,OFFSET MESS2
              JB        STAR4
              CALL      CRLF
              CALL      XUJG
              CALL      BCJG
              MOV       DX,OFFSET MESS3
      STAR4:
              MOV       AH,9
              INT       21H
              INT       20H
      SAVESP  DW        0
       MESS1  DB        13,10,'  Syntax:',13,10
              DB        '     JS  <Expression>  [10]',13,10,'$'
       MESS2  DB        'Error in expression !$'
       MESS3  DB        13,10,'$'
        CODE  ENDS
              END       NEWSTAR