PIC单片机TMR0中断

list p=16f876
            #include 

;--------------------------
;定时计数单元
HW_TIME    EQU        0X40
;-----------------------------
;定时常数
HW_TIMECT0      EQU        0XDF;TMR0定时器时间常数，载波信号频率37.88KHz(13.2us)
HW_TIMECT1      EQU        0X64;发送信号位间隔，*(1.32ms)
HW_TIMECT3      EQU        0X31;
;-------------------------------------
        ORG    0X00        
    GOTO    HW_RECEIVE
;------------------------------------
        ORG     0X04        
        GOTO    INT
;---------------------------------------
bcf    INTCON,GIE
BCF     INTCON,T0IF     ;(T0IF)定时器溢出标志位清零
BCF    INTCON,T0IE     ;关TMR0中断(T0IE)位清零
BANKSEL    OPTION_REG
CLRF    OPTION_REG    
    BANKSEL    HW_TIME
    MOVLW    HW_TIMECT3
    MOVWF    HW_TIME
        MOVLW   HW_TIMECT0
        MOVWF   TMR0
    BANKSEL    INTCON
    BSF    INTCON,T0IE
    BSF    INTCON,GIE 
INT;中断
    movwf    W_TEMP
    movf    STATUS,0
    bcf    STATUS,RP0;working in bank0
    movwf    STATUS_TEMP
    MOVLW   HW_TIMECT0
        MOVWF   TMR0         ;重装定时常数
        BCF     INTCON,T0IF    ;清除中断溢出标志位(T0IF)
;----------------------------------------------------------------------
        DECFSZ  HW_TIME,1           ;为零，间跳，定时时间到
        GOTO    HW_LEAVE1
        MOVLW   HW_TIMECT1         ;重装时间常数
        MOVWF   HW_TIME
    BSF     HW_Sign,1
HW_LEAVE1
    BANKSEL    STATUS_TEMP
    MOVF    STATUS_TEMP,0
    MOVWF    STATUS
    MOVF    W_TEMP
    RETFIE