nios+timer+uart dont work! why?

Thank you kevin, I have decided this issue as follows:

# include <unistd.h>

# include <fcntl.h>

# include "alt_types.h"

# include "altera_avalon_pio_regs.h"

# include "altera_avalon_uart_regs.h"

# include "altera_avalon_timer_regs.h"

# include "sys/alt_irq.h"

# include "system.h"

unsigned char text_buffer;

unsigned char int_flag;

int send_char_buffer_to_uart(unsigned char *buf, int size){

int comport,status;

comport=open("/dev/uart",O_WRONLY);

status=(write(comport, buf, size));

close(comport);

return status;

}

int get_char_buffer_from_uart(unsigned char *buf, int size){

int comport,received_bytes_num;

comport=open("/dev/uart",O_RDONLY);

received_bytes_num=(read(comport, buf, size));

close(comport);

return received_bytes_num;

}

void handle_timer_interrupt (void* context, alt_u32 id)

{

static alt_u8 value = 0x00;

value = value + 1;

int_flag=1;

IOWR_ALTERA_AVALON_PIO_DATA(LEDS_BASE, ~value);

IOWR_ALTERA_AVALON_TIMER_STATUS(SYSTEM_TIMER_BASE, 0);

}

int main(void){

alt_irq_register(SYSTEM_TIMER_IRQ, 0, handle_timer_interrupt);

int_flag=0;

while(1){

if(int_flag){

send_char_buffer_to_uart("hello",5);

int_flag=0;

}

}

}