STM8S103进入中断后无法退出，求助

/*        BASIC INTERRUPT VECTOR TABLE FOR STM8 devices

 *        Copyright (c) 2007 STMicroelectronics

 */

//这里使用的是定时器4

typedef void [url=home.php?mod=space&uid=1095855]@far[/url] (*interrupt_handler_t)(void);



struct interrupt_vector {

        unsigned char interrupt_instruction;

        interrupt_handler_t interrupt_handler;

};



@far [url=home.php?mod=space&uid=422518]@interrupt[/url] void NonHandledInterrupt (void)

{

        /* in order to detect unexpected events during development, 

           it is recommended to set a breakpoint on the following instruction

        */

        return;

}





extern void _stext();     /* startup routine */

@far @interrupt void timer4_out (void);

struct interrupt_vector const _vectab[] = {

        {0x82, (interrupt_handler_t)_stext}, /* reset */

        {0x82, NonHandledInterrupt}, /* trap  */

        {0x82, NonHandledInterrupt}, /* irq0  */

        {0x82, NonHandledInterrupt}, /* irq1  */

        {0x82, NonHandledInterrupt}, /* irq2  */

        {0x82, NonHandledInterrupt}, /* irq3  */

        {0x82, NonHandledInterrupt}, /* irq4  */

        {0x82, NonHandledInterrupt}, /* irq5  */

        {0x82, NonHandledInterrupt}, /* irq6  */

        {0x82, NonHandledInterrupt}, /* irq7  */

        {0x82, NonHandledInterrupt}, /* irq8  */

        {0x82, NonHandledInterrupt}, /* irq9  */

        {0x82, NonHandledInterrupt}, /* irq10 */

        {0x82, NonHandledInterrupt}, /* irq11 */

        {0x82, NonHandledInterrupt}, /* irq12 */

        {0x82, NonHandledInterrupt}, /* irq13 */

        {0x82, NonHandledInterrupt}, /* irq14 */

        {0x82, NonHandledInterrupt}, /* irq15 */

        {0x82, NonHandledInterrupt}, /* irq16 */

        {0x82, NonHandledInterrupt}, /* irq17 */

        {0x82, NonHandledInterrupt}, /* irq18 */

        {0x82, NonHandledInterrupt}, /* irq19 */

        {0x82, NonHandledInterrupt}, /* irq20 */

        {0x82, NonHandledInterrupt}, /* irq21 */

        {0x82, NonHandledInterrupt}, /* irq22 */

        {0x82, timer4_out}, /* irq23 */

        {0x82, NonHandledInterrupt}, /* irq24 */

        {0x82, NonHandledInterrupt}, /* irq25 */

        {0x82, NonHandledInterrupt}, /* irq26 */

        {0x82, NonHandledInterrupt}, /* irq27 */

        {0x82, NonHandledInterrupt}, /* irq28 */

        {0x82, NonHandledInterrupt}, /* irq29 */

};

void init_io(void)

{

        PB_CR1 &= ~(1<<5);

        PB_CR2 &= ~(1<<5);

        PB_DDR |= (1<<5);

        PB_ODR = 0xff;

}

void init_timer4 (void)

{

        TIM4_PSCR = 0x02;

        TIM4_ARR = 0xFA;

        TIM4_CNTR = 0xFA;

        TIM4_IER |= (1<<0);

}

@far @interrupt void timer4_out (void)

{

        count++;

}

void init_clk (void)

{

        CLK_CMSR = 0xe1;

        CLK_CKDIVR =((0x11<<3)|(0x01));//8|2

        CLK_PCKENR1 |= (1<<4);

}//1M

void main (void)

{

        _asm("sim");

        init_io();//板上一个LED,初始化LED输出的接口

        init_clk();//初始化系统时钟

        init_timer4();//初始化定时器4

        TIM4_CR1 = (1<<0);

        _asm("rim");

        while(1)

        {

                if(count>1000)//当定时器中断服务程序的计数大于1000的时候执行括号内的程序

                {

                        PB_ODR^=(1<<5);//LED接口取反

                        count = 0;//计数清零

                }

        }

}