asample2.a51

c51学习的好书！

NAME    STRING_IO
EXTRN   BIT    (TXTBIT)
EXTRN   CODE   (PUTCHAR)
PUBLIC  PUT_CRLF, PUTSTRING
STRING_ROUTINES  SEGMENT  CODE
        RSEG  STRING_ROUTINES
CR      EQU   0DH          
LF      EQU   0AH                
PUT_CRLF:                         ; 子程序PUT_CRLF输出回车和换行
        MOV   A,#CR
        CALL  PUTCHAR
        MOV   A,#LF
        CALL  PUTCHAR
        RET
PUTSTRING:                        ; 子程序PUTSTRING测试TXTBIT位以决定位于CODE
        JB    TXTBIT,PS1          ; 存储器或XDATA存储器中的字符串
        CLR   A
        MOVC  A,@A+DPTR
        SJMP  PS2
PS1:    MOVX  A,@DPTR
PS2:    JZ    EXIT
        CALL  PUTCHAR
        INC   DPTR
        SJMP  PUTSTRING
EXIT:   RET
        END