rjexp19.asm

显示屏相关程序实现显示屏点亮控制等功能.

CRLF MACRO  
     MOV AH,02H
     MOV DL,0DH
     INT 21H
     MOV AH,02H
     MOV DL,0AH
     INT 21H
ENDM

DATA SEGMENT  
HANDLE DW ?
NAMEBUF DB 49
        DB ?
        DB 50 DUP (?)
DATBUF  DB 200 DUP(?)
INTRO DB 0DH,0AH,'ENTER PATHNAME:$'
EMESS DB 'ERROR $'
DATA ENDS

STACK SEGMENT
STA DW 32 DUP (?)
TOP DW ?
STACK ENDS

CODE SEGMENT
ASSUME CS:CODE,DS:DATA,ES:DATA,SS:STACK
START:  MOV 	AX,DATA
        MOV 	DS,AX
        MOV 	ES,AX
        MOV 	SP,TOP
        MOV 	AH,09H
        MOV 	DX,OFFSET INTRO
        INT 	21H
        MOV 	AH,0AH
        MOV 	DX,OFFSET NAMEBUF
        INT		21H
        CRLF
        MOV	SI,OFFSET NAMEBUF
        MOV 	BL,[SI+1]
        MOV 	BH,0
        MOV 	BYTE PTR [NAMEBUF+BX+2],0
        MOV 	AH,3DH
        MOV 	AL,0
        MOV 	DX,OFFSET NAMEBUF+2
        INT 	21H
        MOV 	BX,AX
        JC 		ERROR
        MOV 	HANDLE,AX
TTT:    MOV 	AH,3FH
        MOV	BX,HANDLE    ;文件代号
        MOV	CX,200       ;读取字节数
        MOV	DX,OFFSET DATBUF  ;缓冲区首址
         INT	21H          ;读文件
        MOV	BX,AX        ;读文件出错转ERROR
        JC		ERROR
        CMP	AX,0
        JE		EXIT         ;读取字符数为0,则到文件尾,转EXIT
        MOV	CX,AX        ;字符数
        MOV	BX,OFFSET DATBUF  ;BX指向传输缓冲区首址
   JJJ: MOV		AH,2            ;显示字符的功能调用
        MOV	DL,[BX]         ;取字符
        CMP	AL,1AH
        JE		EXIT            ;若为文件结束符则转EXIT
        INT		21H             ;显示
        INC		BX              ;指向下一个字符
        LOOP	JJJ             ;循环
        JMP		TTT             ;读取文件下一部分
EXIT:   MOV	AH,3EH
        MOV	BX,HANDLE      ;关闭文件
        INT		21H
        MOV	BX,AX
        JC		ERROR          ;关闭出错转ERROR
        MOV	AX,4C00H
        INT		21H            ;返回DOS
ERROR:MOV		AH,09H
       MOV		DX,OFFSET EMESS   ;显示出错信息
      INT		21H
      CALL		BINIHEX           ;显示出错代号
      JMP		EXIT
BINIHEX  PROC  NEAR
      MOV		CH,04
ROT:  MOV		CL,04
      ROL		BX,CL
      MOV		AL,BL
      AND		AL,0FH
      ADD		AL,30H
      CMP		AL,3AH
      JL		PRINT
      ADD		AL,27H       ;参见实验18的程序清单
PRINT:MOV		DL,AL
      MOV		AH,02
      INT		21H
      DEC		CH
      JNZ		ROT
      RET
BINIHEX	ENDP
CODE   ENDS
		END  START