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

[Altera_Forum]

/* 

* 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 }

[Altera_Forum]

if i add these codes&#65306;IOWR_ALTERA_AVALON_TIMER_PERIODH(TIMER_BASE,25000> >16); 

IOWR_ALTERA_AVALON_TIMER_PERIODL(TIMER_BASE,25000 && 0xffff); the program won't work,why i have ready selected the"writable period"

[Altera_Forum]

You probably meant '25000 & 0xffff' instead of '25000 && 0xffff' which will result in 25000 instead of 1.

[Altera_Forum]

thanks very much,i'll try it,but i've already used that two statements many times before in my project,and there is nothing wrong.