why the results i run or debug this code are different,your help would be appreciated

/*

* control.c

*

* Created on: 2012-11-15

* Author: zhanghan

*/

# include "alt_types.h"# include "altera_avalon_timer_regs.h"# include "sys/alt_irq.h"# include "system.h"# include <stdio.h># include <unistd.h>

void timer_ISR(void);

void init_spi(void);

int d;

int main(void)

{

printf("\nWelcome!!!\n");

init_spi();

printf("\nSpi initial succeed!\n");

while(1)

{

}

return 0;

}

void init_spi(void)

{

d=0;

IOWR_ALTERA_AVALON_TIMER_STATUS(TIMER_BASE,0x00);

// IOWR_ALTERA_AVALON_TIMER_PERIODH(TIMER_BASE,25000>>16);

// IOWR_ALTERA_AVALON_TIMER_PERIODL(TIMER_BASE,25000 && 0xffff);

IOWR_ALTERA_AVALON_TIMER_CONTROL(TIMER_BASE,0x07); //start the timer

alt_irq_register(TIMER_IRQ,(void*)TIMER_BASE,(void*)timer_ISR);

}

//interrupt service routine

void timer_ISR(void)

{

printf("\nthe data is %d \n" ,d);

d++;

IOWR_ALTERA_AVALON_TIMER_STATUS(TIMER_BASE, 0x00); //clear the timeout bit

}